Bump up the version to v0.15.5

Bump up the version to v0.15.4
Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>
2025-04-01 23:16:01 +03:00 · 2023-12-20 18:28:15 +08:00 · 2023-12-20 17:56:18 +08:00 · 2023-12-20 09:18:10 +08:00 · 2023-12-20 00:32:00 +08:00 · 2023-12-19 23:45:19 +08:00
40 changed files with 2093 additions and 837 deletions
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@ -16,7 +16,7 @@ jobs:
      fail-fast: false
      matrix:
        os: [ubuntu-20.04, ubuntu-22.04, macos-11, macos-12]
-        etcd: [v3.2.26, v3.3.11, v3.4.13, v3.5.7]
+        etcd: [v3.2.32, v3.3.27, v3.4.27, v3.5.9]
        exclude:
          - os: ubuntu-20.04
            etcd: v3.2.26
@ -243,6 +243,10 @@ jobs:

          # tests without auth

+          echo "Run the etcd resolver test ........................."
+          # there's no ipv6 on github CI runner
+          # ./build/bin/EtcdResolverTest
+
          echo "Run the etcd sync test ........................."
          ./build/bin/EtcdSyncTest

@ -399,6 +403,26 @@ jobs:
          killall -TERM etcd
          sleep 5

+      - name: Etcd Member test
+        run: |
+          killall -TERM etcd || true
+          sleep 5
+
+          export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib:/usr/local/lib/x86_64-linux-gnu
+
+          # use etcd v3 api
+          export ETCDCTL_API="3"
+          
+
+          rm -rf default.etcd
+          /usr/local/bin/etcd &
+          sleep 5
+
+          ./build/bin/EtcdMemberTest
+
+          killall -TERM etcd
+          sleep 5
+        
      - name: Check ccache
        run: |
          ccache --show-stats
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -5,7 +5,7 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)

 set(etcd-cpp-api_VERSION_MAJOR 0)
 set(etcd-cpp-api_VERSION_MINOR 15)
-set(etcd-cpp-api_VERSION_PATCH 0)
+set(etcd-cpp-api_VERSION_PATCH 5)
 set(etcd-cpp-api_VERSION ${etcd-cpp-api_VERSION_MAJOR}.${etcd-cpp-api_VERSION_MINOR}.${etcd-cpp-api_VERSION_PATCH})
 set(CMAKE_PROJECT_HOMEPAGE_URL https://github.com/etcd-cpp-apiv3/etcd-cpp-apiv3)

@ -26,6 +26,7 @@ if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
    )
 endif()

+option(BUILD_WITH_NO_EXCEPTIONS "Build etcd-cpp-apiv3 with disabling exception handling, i.e., -fno-exceptions" OFF)
 option(BUILD_SHARED_LIBS "Build etcd-cpp-apiv3 shared libraries" ON)
 option(BUILD_ETCD_CORE_ONLY "Build etcd-cpp-apiv3 core library (the synchronous runtime) only" OFF)
 option(BUILD_ETCD_TESTS "Build etcd-cpp-apiv3 test cases" OFF)
@ -88,6 +89,21 @@ macro(use_cxx target)
    endif()
 endmacro(use_cxx)

+macro(set_exceptions target)
+    if(BUILD_WITH_NO_EXCEPTIONS)
+        if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+            target_compile_options(${target} PRIVATE "-fno-exceptions")
+        elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
+            target_compile_options(${target} PRIVATE "-fno-exceptions")
+        elseif(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
+            target_compile_options(${target} PRIVATE "-fno-exceptions")
+        elseif(CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+            target_compile_options(${target} PRIVATE "/EHs-c-")
+        endif()
+        target_compile_definitions(${target} PUBLIC -D_ETCD_NO_EXCEPTIONS)
+    endif()
+endmacro(set_exceptions)
+
 if(APPLE)
    # If we're on OS X check for Homebrew's copy of OpenSSL instead of Apple's
    if(NOT OpenSSL_DIR)
@ -120,10 +136,34 @@ if(Protobuf_PROTOC_EXECUTABLE)
    endif()
 endif()

+# When cross compiling we look for the native protoc compiler
+# overwrite protobuf::protoc with the proper protoc
+if(CMAKE_CROSSCOMPILING)
+    find_program(Protobuf_PROTOC_EXECUTABLE REQUIRED NAMES protoc)
+    if(NOT TARGET protobuf::protoc)
+        add_executable(protobuf::protoc IMPORTED)
+    endif()
+    set_target_properties(protobuf::protoc PROPERTIES
+        IMPORTED_LOCATION "${Protobuf_PROTOC_EXECUTABLE}")
+endif()
+
 find_package(gRPC QUIET)
-if(gRPC_FOUND AND TARGET gRPC::grpc AND TARGET gRPC::grpc_cpp_plugin)
-    set(GRPC_LIBRARIES gRPC::gpr gRPC::grpc gRPC::grpc++)
+if(gRPC_FOUND AND TARGET gRPC::grpc)
+    # When cross compiling we look for the native grpc_cpp_plugin
+    if(CMAKE_CROSSCOMPILING)
+        find_program(GRPC_CPP_PLUGIN REQUIRED NAMES grpc_cpp_plugin)
+        if(NOT TARGET gRPC::grpc_cpp_plugin)
+            add_executable(gRPC::grpc_cpp_plugin IMPORTED)
+        endif()
+        set_target_properties(gRPC::grpc_cpp_plugin PROPERTIES
+                IMPORTED_LOCATION "${GRPC_CPP_PLUGIN}")
+    elseif(TARGET gRPC::grpc_cpp_plugin)
        get_target_property(GRPC_CPP_PLUGIN gRPC::grpc_cpp_plugin LOCATION)
+    else()
+        message(FATAL_ERROR "Found gRPC but no gRPC CPP plugin defined")
+    endif()
+
+    set(GRPC_LIBRARIES gRPC::gpr gRPC::grpc gRPC::grpc++)
    get_target_property(GRPC_INCLUDE_DIR gRPC::grpc INTERFACE_INCLUDE_DIRECTORIES)
 else()
    include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/FindGRPC.cmake)
@ -142,6 +182,9 @@ include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/GenerateProtobufGRPC.cmake)
 if(gRPC_VERSION VERSION_LESS "1.21" OR gRPC_VERSION VERSION_GREATER "1.31")
    add_definitions(-DWITH_GRPC_CHANNEL_CLASS)
 endif()
+if(gRPC_VERSION VERSION_LESS "1.17")
+    add_definitions(-DWITH_GRPC_CREATE_CHANNEL_INTERNAL_UNIQUE_POINTER)
+endif()

 # will set `PROTOBUF_GENERATES`, indicates all generated .cc files, and a target `protobuf_generates`.
 include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/GenerateProtobuf.cmake)
@ -181,9 +224,13 @@ if(NOT CMAKE_CXX_COMPILER_ID MATCHES "MSVC")
 endif()

 check_cxx_compiler_flag(-Wno-c++17-extensions W_NO_CPP17_EXTENSIONS)
+check_cxx_compiler_flag(-Wno-extra-semi W_NO_EXTRA_SEMI)
 if(W_NO_CPP17_EXTENSIONS)
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-c++17-extensions")
 endif()
+if(W_NO_EXTRA_SEMI)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-extra-semi")
+endif()

 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR}/bin)

@ -205,6 +252,7 @@ if(NOT BUILD_ETCD_CORE_ONLY)
 endif()
 install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/etcd/v3/action_constants.hpp
              ${CMAKE_CURRENT_SOURCE_DIR}/etcd/v3/Transaction.hpp
+              ${CMAKE_CURRENT_SOURCE_DIR}/etcd/v3/Member.hpp
              DESTINATION include/etcd/v3)

 configure_file(etcd-cpp-api-config.in.cmake
@ -290,6 +338,7 @@ set(CPACK_DEBIAN_PACKAGE_INSTALL "/usr/lib/lib*.so*"
                                 "/usr/include/etcd/*.hpp"
                                 "/usr/include/etcd/v3/action_constants.hpp"
                                 "/usr/include/etcd/v3/Transaction.hpp"
+                                 "/usr/include/etcd/v3/Member.hpp"
 )

 set(CPACK_DEBIAN_PACKAGE_BUILD_NUMBER_PREFIX "")
--- a/README.md
+++ b/README.md
@ -83,6 +83,36 @@ dependencies have been successfully installed:
    cmake ..
    make -j$(nproc) && make install

+## Using this package in your CMake project
+
+To use this package in your CMake project, you can either
+
+- install, then find the library using `find_package()`:
+
+  ```cmake
+  find_package(etcd-cpp-apiv3 REQUIRED)
+  target_link_libraries(your_target PRIVATE etcd-cpp-api)
+  ```
+
+- or, add this repository as a subdirectory in your project, and link the library directly:
+
+  ```cmake
+  add_subdirectory(thirdparty/etcd-cpp-apiv3)
+  target_link_libraries(your_target PRIVATE etcd-cpp-api)
+  ```
+
+- or, use [FetchContent](https://cmake.org/cmake/help/latest/module/FetchContent.html):
+
+  ```cmake
+  include(FetchContent)
+  FetchContent_Declare(
+    etcd-cpp-apiv3
+    https://github.com/etcd-cpp-apiv3/etcd-cpp-apiv3.git
+  )
+  FetchContent_MakeAvailable(etcd-cpp-apiv3)
+  target_link_libraries(your_target PRIVATE etcd-cpp-api)
+  ```
+
 ## Compatible etcd version

 The _etcd-cpp-apiv3_ should work well with etcd > 3.0. Feel free to issue an issue to us on
@ -192,6 +222,14 @@ Connecting to multiple endpoints is supported:
  etcd::Client etcd("http://a.com:2379;http://b.com:2379;http://c.com:2379");
 ```

+### IPv6
+
+Connecting to IPv6 endpoints is supported:
+
+```c++
+  etcd::Client etcd("http://::1:2379");
+```
+
 Behind the screen, gRPC's load balancer is used and the round-robin strategy will
 be used by default.

@ -495,10 +533,11 @@ some specific conditions.
 Values can be deleted with the `rm` method passing the key to be deleted as a parameter. The key
 should point to an existing value. There are conditional variations for deletion too.

-* `rm_if(key, value, old_value)` deletes an already existing value but only if the previous
+* `rm(std::string const& key)` unconditionally deletes the given key
+* `rm_if(key, old_value)` deletes an already existing value but only if the previous
  value equals with old_value. If the values does not match returns with "Compare failed" error
  (code `ERROR_COMPARE_FAILED`)
-* `rm_if(key, value, old_index)` deletes an already existing value but only if the index of
+* `rm_if(key, old_index)` deletes an already existing value but only if the index of
  the previous value equals with old_index. If the indices does not match returns with "Compare
  failed" error (code `ERROR_COMPARE_FAILED`)

@ -832,6 +871,8 @@ Without handler, the internal state can be checked via `KeepAlive::Check()` and
 the async exception when there are errors during keeping the lease alive.

 Note that even with `handler`, the `KeepAlive::Check()` still rethrow if there's an async exception.
+When the library is built with `-fno-exceptions`, the `handler` argument and the `Check()` method
+will abort the program when there are errors during keeping the lease alive.

 ### Etcd transactions

@ -852,11 +893,32 @@ Transactions in etcd supports set a set of comparison targets to specify the con
  etcdv3::Transaction txn;

  // setup the conditions
-  txn.reset_key("/test/x1");
-  txn.init_compare("1", etcdv3::CompareResult::EQUAL, etcdv3::CompareTarget::VALUE);
+  txn.add_compare_value("/test/x1", "1");
+  txn.add_compare_value("/test/x2", "2");

-  txn.reset_key("/test/x2");
-  txn.init_compare("2", etcdv3::CompareResult::EQUAL, etcdv3::CompareTarget::VALUE);
+  // or, compare the last modified revision
+  txn.add_compare_mod("/test/x3", 0);  // not exists
+  txn.add_compare_mod("/test/x4", etcdv3::CompareResult::GREATER, 1234);  // the modified revision is greater than 1234
+```
+
+High-level APIs (e.g., `compare_and_create`, `compare_and_swap`) are also provided, e.g.,
+`fetch-and-add` operation can be implemented as
+
+```cpp
+  auto fetch_and_add = [](etcd::Client& client,
+                          std::string const& key) -> void {
+    auto value = stoi(client.get(key).get().value().as_string());
+    while (true) {
+      auto txn = etcdv3::Transaction();
+      txn.setup_compare_and_swap(key, std::to_string(value),
+                                 std::to_string(value + 1));
+      etcd::Response resp = client.txn(txn).get();
+      if (resp.is_ok()) {
+        break;
+      }
+      value = stoi(resp.value().as_string());
+    }
+  };
 ```

 See full example of the usages of transaction APIs, please refer to [./tst/TransactionTest.cpp](./tst/TransactionTest.cpp),
@ -908,7 +970,15 @@ The observer stream will be canceled when been destructed.

 for more details, please refer to [etcd/Client.hpp](./etcd/Client.hpp) and [tst/ElectionTest.cpp](./tst/ElectionTest.cpp).

-### TODO
+## `-fno-exceptions`
+
+The _etcd-cpp-apiv3_ library supports to be built with `-fno-exceptions` flag, controlled by the
+cmake option `BUILD_WITH_NO_EXCEPTIONS=ON/OFF` (defaults to `OFF`).
+
+When building with `-fno-exceptions`, the library will abort the program under certain circumstances,
+e.g., when calling `.Check()` method of `KeepAlive` and there are errors during keeping the lease alive,
+
+## TODO

 1. Cancellation of asynchronous calls(except for watch)

--- a/etcd-cpp-api-config.in.cmake
+++ b/etcd-cpp-api-config.in.cmake
@ -32,5 +32,8 @@ set(ETCD_CPP_INCLUDE_DIRS "${ETCD_CPP_INCLUDE_DIR}")
 include(FindPackageMessage)
 find_package_message(etcd
    "Found etcd: ${CMAKE_CURRENT_LIST_FILE} (found version \"@etcd-cpp-api_VERSION@\")"
-    "etcd-cpp-apiv3 version: @etcd-cpp-api_VERSION@\netcd-cpp-apiv3 libraries: ${ETCD_CPP_LIBRARIES}, \netcd-cpp-apiv3 core libraries: ${ETCD_CPP_CORE_LIBRARIES}\ninclude directories: ${ETCD_CPP_INCLUDE_DIRS}"
+    "etcd-cpp-apiv3 version: @etcd-cpp-api_VERSION@\n"
+    "etcd-cpp-apiv3 libraries: ${ETCD_CPP_LIBRARIES}\n"
+    "etcd-cpp-apiv3 core libraries: ${ETCD_CPP_CORE_LIBRARIES}\n"
+    "include directories: ${ETCD_CPP_INCLUDE_DIRS}"
 )
--- a/etcd/Client.hpp
+++ b/etcd/Client.hpp
@ -271,15 +271,6 @@ class Client {
   */
  pplx::task<Response> get(std::string const& key, int64_t revision);

-  /**
-   * Sets the value of a key. The key will be modified if already exists or
-   * created if it does not exists.
-   * @param key is the key to be created or modified
-   * @param value is the new value to be set
-   */
-  pplx::task<Response> set(std::string const& key, std::string const& value,
-                           int ttl = 0);
-
  /**
   * Sets the value of a key. The key will be modified if already exists or
   * created if it does not exists.
@ -288,15 +279,7 @@ class Client {
   * @param leaseId is the lease attached to the key
   */
  pplx::task<Response> set(std::string const& key, std::string const& value,
-                           int64_t leaseId);
-
-  /**
-   * Creates a new key and sets it's value. Fails if the key already exists.
-   * @param key is the key to be created
-   * @param value is the value to be set
-   */
-  pplx::task<Response> add(std::string const& key, std::string const& value,
-                           int ttl = 0);
+                           const int64_t leaseId = 0);

  /**
   * Creates a new key and sets it's value. Fails if the key already exists.
@ -305,7 +288,7 @@ class Client {
   * @param leaseId is the lease attached to the key
   */
  pplx::task<Response> add(std::string const& key, std::string const& value,
-                           int64_t leaseId);
+                           const int64_t leaseId = 0);

  /**
   * Put a new key-value pair.
@ -315,12 +298,13 @@ class Client {
  pplx::task<Response> put(std::string const& key, std::string const& value);

  /**
-   * Modifies an existing key. Fails if the key does not exists.
-   * @param key is the key to be modified
-   * @param value is the new value to be set
+   * Put a new key-value pair.
+   * @param key is the key to be put
+   * @param value is the value to be put
+   * @param leaseId is the lease id to be associated with the key
   */
-  pplx::task<Response> modify(std::string const& key, std::string const& value,
-                              int ttl = 0);
+  pplx::task<Response> put(std::string const& key, std::string const& value,
+                           const int64_t leaseId);

  /**
   * Modifies an existing key. Fails if the key does not exists.
@ -329,18 +313,7 @@ class Client {
   * @param leaseId is the lease attached to the key
   */
  pplx::task<Response> modify(std::string const& key, std::string const& value,
-                              int64_t leaseId);
-
-  /**
-   * Modifies an existing key only if it has a specific value. Fails if the key
-   * does not exists or the original value differs from the expected one.
-   * @param key is the key to be modified
-   * @param value is the new value to be set
-   * @param old_value is the value to be replaced
-   */
-  pplx::task<Response> modify_if(std::string const& key,
-                                 std::string const& value,
-                                 std::string const& old_value, int ttl = 0);
+                              const int64_t leaseId = 0);

  /**
   * Modifies an existing key only if it has a specific value. Fails if the key
@ -352,19 +325,8 @@ class Client {
   */
  pplx::task<Response> modify_if(std::string const& key,
                                 std::string const& value,
-                                 std::string const& old_value, int64_t leaseId);
-
-  /**
-   * Modifies an existing key only if it has a specific modification index
-   * value. Fails if the key does not exists or the modification index of the
-   * previous value differs from the expected one.
-   * @param key is the key to be modified
-   * @param value is the new value to be set
-   * @param old_index is the expected index of the original value
-   */
-  pplx::task<Response> modify_if(std::string const& key,
-                                 std::string const& value, int64_t old_index,
-                                 int ttl = 0);
+                                 std::string const& old_value,
+                                 const int64_t leaseId = 0);

  /**
   * Modifies an existing key only if it has a specific modification index
@ -377,11 +339,13 @@ class Client {
   */
  pplx::task<Response> modify_if(std::string const& key,
                                 std::string const& value, int64_t old_index,
-                                 int64_t leaseId);
+                                 const int64_t leaseId = 0);

  /**
   * Removes a single key. The key has to point to a plain, non directory entry.
   * @param key is the key to be deleted
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the key does not exist.
   */
  pplx::task<Response> rm(std::string const& key);

@ -389,6 +353,8 @@ class Client {
   * Removes a single key but only if it has a specific value. Fails if the key
   * does not exists or the its value differs from the expected one.
   * @param key is the key to be deleted
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the key does not exist.
   */
  pplx::task<Response> rm_if(std::string const& key,
                             std::string const& old_value);
@ -399,6 +365,8 @@ class Client {
   * from the expected one.
   * @param key is the key to be deleted
   * @param old_index is the expected index of the existing value
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the key does not exist.
   */
  pplx::task<Response> rm_if(std::string const& key, int64_t old_index);

@ -408,6 +376,8 @@ class Client {
   * @param key is the directory to be created to be listed
   * @param recursive if true then delete a whole subtree, otherwise deletes
   * only an empty directory.
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the no key been deleted.
   */
  pplx::task<Response> rmdir(std::string const& key, bool recursive = false);

@ -419,6 +389,8 @@ class Client {
   *
   * @param key is the directory to be created to be listed
   * @param range_end is the end of key range to be removed.
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the no key been deleted.
   */
  pplx::task<Response> rmdir(std::string const& key, const char* range_end);

@ -427,6 +399,8 @@ class Client {
   *
   * @param key is the directory to be created to be listed
   * @param range_end is the end of key range to be removed.
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the no key been deleted.
   */
  pplx::task<Response> rmdir(std::string const& key,
                             std::string const& range_end);
@ -656,6 +630,25 @@ class Client {
   */
  pplx::task<Response> leases();

+  /**
+   * Add an etcd member to the etcd cluster, equivalent to `etcdctl member add`.
+   * @param peer_urls is comma separated list of URLs for the new member.
+   * @param is_learner is true if the added member is a learner.
+   */
+  pplx::task<Response> add_member(std::string const& peer_urls,
+                                  bool is_learner);
+
+  /**
+   * List all members, equivalent to `etcdctl member list`.
+   */
+  pplx::task<Response> list_member();
+
+  /**
+   * Add an etcd member to the etcd cluster, equivalent to `etcdctl member add`.
+   * @param member_id is the ID of the member to be removed.
+   */
+  pplx::task<Response> remove_member(const uint64_t member_id);
+
  /**
   * Gains a lock at a key, using a default created lease, using the default
   * lease (10 seconds), with keeping alive has already been taken care of by
--- a/etcd/KeepAlive.hpp
+++ b/etcd/KeepAlive.hpp
@ -85,10 +85,10 @@ class KeepAlive {
  ~KeepAlive();

 protected:
-  // automatically refresh loop
-  void refresh();
-  // refresh once immediately
-  void refresh_once();
+  // automatically refresh loop, returns the error message if failed
+  std::string refresh();
+  // refresh once immediately, returns the error message if failed
+  std::string refresh_once();

  struct EtcdServerStubs;
  struct EtcdServerStubsDeleter {
--- a/etcd/Response.hpp
+++ b/etcd/Response.hpp
@ -9,6 +9,7 @@
 #include <vector>

 #include "etcd/Value.hpp"
+#include "etcd/v3/Member.hpp"

 namespace etcdv3 {
 class AsyncWatchAction;
@ -34,7 +35,7 @@ class KeepAlive;
 class Watcher;

 /**
- * The Reponse object received for the requests of etcd::Client
+ * The Response object received for the requests of etcd::Client
 */
 class Response {
 public:
@ -208,6 +209,11 @@ class Response {
   */
  std::vector<int64_t> const& leases() const;

+  /**
+   * Returns the member list.
+   */
+  std::vector<etcdv3::Member> const& members() const;
+
 protected:
  Response(const etcdv3::V3Response& response,
           std::chrono::microseconds const& duration);
@ -239,6 +245,9 @@ class Response {
  // for lease list
  std::vector<int64_t> _leases;

+  // for member list
+  std::vector<etcdv3::Member> _members;
+
  friend class Client;
  friend class SyncClient;
  friend class KeepAlive;
--- a/etcd/SyncClient.hpp
+++ b/etcd/SyncClient.hpp
@ -29,6 +29,9 @@ class AsyncLeaseKeepAliveAction;
 class AsyncLeaseTimeToLiveAction;
 class AsyncLeaseLeasesAction;
 class AsyncLockAction;
+class AsyncAddMemberAction;
+class AsyncListMemberAction;
+class AsyncRemoveMemberAction;
 class AsyncUnlockAction;
 class AsyncPutAction;
 class AsyncRangeAction;
@ -327,14 +330,6 @@ class SyncClient {
   */
  Response get(std::string const& key, int64_t revision);

-  /**
-   * Sets the value of a key. The key will be modified if already exists or
-   * created if it does not exists.
-   * @param key is the key to be created or modified
-   * @param value is the new value to be set
-   */
-  Response set(std::string const& key, std::string const& value, int ttl = 0);
-
  /**
   * Sets the value of a key. The key will be modified if already exists or
   * created if it does not exists.
@ -343,14 +338,7 @@ class SyncClient {
   * @param leaseId is the lease attached to the key
   */
  Response set(std::string const& key, std::string const& value,
-               int64_t leaseId);
-
-  /**
-   * Creates a new key and sets it's value. Fails if the key already exists.
-   * @param key is the key to be created
-   * @param value is the value to be set
-   */
-  Response add(std::string const& key, std::string const& value, int ttl = 0);
+               const int64_t leaseId = 0);

  /**
   * Creates a new key and sets it's value. Fails if the key already exists.
@ -359,7 +347,7 @@ class SyncClient {
   * @param leaseId is the lease attached to the key
   */
  Response add(std::string const& key, std::string const& value,
-               int64_t leaseId);
+               const int64_t leaseId = 0);

  /**
   * Put a new key-value pair.
@ -369,12 +357,13 @@ class SyncClient {
  Response put(std::string const& key, std::string const& value);

  /**
-   * Modifies an existing key. Fails if the key does not exists.
-   * @param key is the key to be modified
-   * @param value is the new value to be set
+   * Put a new key-value pair.
+   * @param key is the key to be put
+   * @param value is the value to be put
+   * @param leaseId is the lease id to be associated with the key
   */
-  Response modify(std::string const& key, std::string const& value,
-                  int ttl = 0);
+  Response put(std::string const& key, std::string const& value,
+               const int64_t leaseId);

  /**
   * Modifies an existing key. Fails if the key does not exists.
@ -383,17 +372,7 @@ class SyncClient {
   * @param leaseId is the lease attached to the key
   */
  Response modify(std::string const& key, std::string const& value,
-                  int64_t leaseId);
-
-  /**
-   * Modifies an existing key only if it has a specific value. Fails if the key
-   * does not exists or the original value differs from the expected one.
-   * @param key is the key to be modified
-   * @param value is the new value to be set
-   * @param old_value is the value to be replaced
-   */
-  Response modify_if(std::string const& key, std::string const& value,
-                     std::string const& old_value, int ttl = 0);
+                  const int64_t leaseId = 0);

  /**
   * Modifies an existing key only if it has a specific value. Fails if the key
@ -404,18 +383,7 @@ class SyncClient {
   * @param leaseId is the lease attached to the key
   */
  Response modify_if(std::string const& key, std::string const& value,
-                     std::string const& old_value, int64_t leaseId);
-
-  /**
-   * Modifies an existing key only if it has a specific modification index
-   * value. Fails if the key does not exists or the modification index of the
-   * previous value differs from the expected one.
-   * @param key is the key to be modified
-   * @param value is the new value to be set
-   * @param old_index is the expected index of the original value
-   */
-  Response modify_if(std::string const& key, std::string const& value,
-                     int64_t old_index, int ttl = 0);
+                     std::string const& old_value, const int64_t leaseId = 0);

  /**
   * Modifies an existing key only if it has a specific modification index
@ -427,11 +395,13 @@ class SyncClient {
   * @param leaseId is the lease attached to the key
   */
  Response modify_if(std::string const& key, std::string const& value,
-                     int64_t old_index, int64_t leaseId);
+                     int64_t old_index, const int64_t leaseId = 0);

  /**
   * Removes a single key. The key has to point to a plain, non directory entry.
   * @param key is the key to be deleted
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the key does not exist.
   */
  Response rm(std::string const& key);

@ -439,6 +409,8 @@ class SyncClient {
   * Removes a single key but only if it has a specific value. Fails if the key
   * does not exists or the its value differs from the expected one.
   * @param key is the key to be deleted
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the key does not exist.
   */
  Response rm_if(std::string const& key, std::string const& old_value);

@ -448,6 +420,8 @@ class SyncClient {
   * from the expected one.
   * @param key is the key to be deleted
   * @param old_index is the expected index of the existing value
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the key does not exist.
   */
  Response rm_if(std::string const& key, int64_t old_index);

@ -457,6 +431,8 @@ class SyncClient {
   * @param key is the directory to be created to be listed
   * @param recursive if true then delete a whole subtree, otherwise deletes
   * only an empty directory.
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the no key been deleted.
   */
  Response rmdir(std::string const& key, bool recursive = false);

@ -468,6 +444,8 @@ class SyncClient {
   *
   * @param key is the directory to be created to be listed
   * @param range_end is the end of key range to be removed.
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the no key been deleted.
   */
  Response rmdir(std::string const& key, const char* range_end);

@ -476,6 +454,8 @@ class SyncClient {
   *
   * @param key is the directory to be created to be listed
   * @param range_end is the end of key range to be removed.
+   *
+   * @return Returns etcdv3::ERROR_KEY_NOT_FOUND if the no key been deleted.
   */
  Response rmdir(std::string const& key, std::string const& range_end);

@ -702,6 +682,24 @@ class SyncClient {
   */
  Response leases();

+  /**
+   * Add an etcd member to the etcd cluster, equivalent to `etcdctl member add`.
+   * @param peer_urls is comma separated list of URLs for the new member.
+   * @param is_learner is true if the added member is a learner.
+   */
+  Response add_member(std::string const& peer_urls, bool is_learner);
+
+  /**
+   * List all members, equivalent to `etcdctl member list`.
+   */
+  Response list_member();
+
+  /**
+   * Remove a member of an etcd cluster, equivalent to `etcdctl member remove`.
+   * @param member_id is the id of the member to be removed.
+   */
+  Response remove_member(uint64_t member_id);
+
  /**
   * Gains a lock at a key, using a default created lease, using the default
   * lease (10 seconds), with keeping alive has already been taken care of by
@ -819,22 +817,21 @@ class SyncClient {
 private:
  // TODO: use std::unique_ptr<>
  std::shared_ptr<etcdv3::AsyncHeadAction> head_internal();
-  std::shared_ptr<etcdv3::AsyncRangeAction> get_internal(std::string const& key,
-                                                         int64_t revision = 0);
-  std::shared_ptr<etcdv3::AsyncSetAction> set_internal(std::string const& key,
-                                                       std::string const& value,
-                                                       int64_t leaseId);
-  std::shared_ptr<etcdv3::AsyncSetAction> add_internal(std::string const& key,
-                                                       std::string const& value,
-                                                       int64_t leaseId);
+  std::shared_ptr<etcdv3::AsyncRangeAction> get_internal(
+      std::string const& key, const int64_t revision = 0);
+  std::shared_ptr<etcdv3::AsyncSetAction> add_internal(
+      std::string const& key, std::string const& value,
+      const int64_t leaseId = 0);
  std::shared_ptr<etcdv3::AsyncPutAction> put_internal(
-      std::string const& key, std::string const& value);
+      std::string const& key, std::string const& value,
+      const int64_t leaseId = 0);
  std::shared_ptr<etcdv3::AsyncUpdateAction> modify_internal(
-      std::string const& key, std::string const& value, int64_t leaseId);
+      std::string const& key, std::string const& value,
+      const int64_t leaseId = 0);
  std::shared_ptr<etcdv3::AsyncCompareAndSwapAction> modify_if_internal(
      std::string const& key, std::string const& value, int64_t old_index,
-      std::string const& old_value, int64_t leaseId,
-      etcdv3::AtomicityType const& atomicity_type);
+      std::string const& old_value, etcdv3::AtomicityType const& atomicity_type,
+      const int64_t leaseId = 0);
  std::shared_ptr<etcdv3::AsyncDeleteAction> rm_internal(
      std::string const& key);
  std::shared_ptr<etcdv3::AsyncCompareAndDeleteAction> rm_if_internal(
@ -859,6 +856,11 @@ class SyncClient {
  std::shared_ptr<etcdv3::AsyncLeaseTimeToLiveAction> leasetimetolive_internal(
      int64_t lease_id);
  std::shared_ptr<etcdv3::AsyncLeaseLeasesAction> leases_internal();
+  std::shared_ptr<etcdv3::AsyncAddMemberAction> add_member_internal(
+      std::string const& peer_urls, bool is_learner);
+  std::shared_ptr<etcdv3::AsyncListMemberAction> list_member_internal();
+  std::shared_ptr<etcdv3::AsyncRemoveMemberAction> remove_member_internal(
+      const uint64_t member_id);
  Response lock_internal(std::string const& key,
                         std::shared_ptr<etcd::KeepAlive> const& keepalive);
  std::shared_ptr<etcdv3::AsyncLockAction> lock_with_lease_internal(
--- a/etcd/Value.hpp
+++ b/etcd/Value.hpp
@ -91,7 +91,9 @@ class Value {
  int64_t leaseId;
 };

-typedef std::vector<Value> Values;
+using Values = std::vector<Value>;
+
+std::ostream& operator<<(std::ostream& os, const Value& value);

 class Event {
 public:
@ -122,7 +124,12 @@ class Event {
  bool _has_kv, _has_prev_kv;
 };

-typedef std::vector<Event> Events;
+using Events = std::vector<Event>;
+
+std::ostream& operator<<(std::ostream& os, const Event::EventType& value);
+
+std::ostream& operator<<(std::ostream& os, const Event& event);
+
 }  // namespace etcd

 #endif
--- a/etcd/Watcher.hpp
+++ b/etcd/Watcher.hpp
@ -162,8 +162,11 @@ class Watcher {
   * Note that you shouldn't use the watcher itself inside the `Wait()` callback
   * as the callback will be invoked in a separate **detached** thread where the
   * watcher may have been destroyed.
+   *
+   * @return true if the callback has been set successfully (no existing
+   * callback).
   */
-  void Wait(std::function<void(bool)> callback);
+  bool Wait(std::function<void(bool)> callback);

  /**
   * Stop the watching action.
--- a/etcd/v3/Action.hpp
+++ b/etcd/v3/Action.hpp
@ -9,10 +9,13 @@
 #include "proto/v3election.grpc.pb.h"
 #include "proto/v3lock.grpc.pb.h"

+#include "etcd/v3/action_constants.hpp"
+
 using grpc::ClientContext;
 using grpc::CompletionQueue;
 using grpc::Status;

+using etcdserverpb::Cluster;
 using etcdserverpb::KV;
 using etcdserverpb::Lease;
 using etcdserverpb::Watch;
@ -42,9 +45,16 @@ struct ActionParameters {
  std::string value;
  std::string old_value;
  std::string auth_token;
+
+  // for cluster management apis
+  std::vector<std::string> peer_urls;
+  bool is_learner;
+  uint64_t member_id;
+
  std::chrono::microseconds grpc_timeout = std::chrono::microseconds::zero();
  KV::Stub* kv_stub;
  Watch::Stub* watch_stub;
+  Cluster::Stub* cluster_stub;
  Lease::Stub* lease_stub;
  Lock::Stub* lock_stub;
  Election::Stub* election_stub;
@ -81,6 +91,27 @@ class Action {
 namespace detail {
 std::string string_plus_one(std::string const& value);
 std::string resolve_etcd_endpoints(std::string const& default_endpoints);
+
+template <typename Req>
+void make_request_with_ranges(Req& req, std::string const& key,
+                              std::string const& range_end,
+                              bool const recursive) {
+  if (!recursive) {
+    req.set_key(key);
+  } else {
+    if (key.empty()) {
+      req.set_key(etcdv3::NUL);
+      req.set_range_end(etcdv3::NUL);
+    } else {
+      req.set_key(key);
+      req.set_range_end(detail::string_plus_one(key));
+    }
+  }
+  if (!range_end.empty()) {
+    req.set_range_end(range_end);
+  }
+}
+
 }  // namespace detail
 }  // namespace etcdv3
 #endif
--- a/etcd/v3/AsyncGRPC.hpp
+++ b/etcd/v3/AsyncGRPC.hpp
@ -37,6 +37,12 @@ using etcdserverpb::LeaseRevokeRequest;
 using etcdserverpb::LeaseRevokeResponse;
 using etcdserverpb::LeaseTimeToLiveRequest;
 using etcdserverpb::LeaseTimeToLiveResponse;
+using etcdserverpb::MemberAddRequest;
+using etcdserverpb::MemberAddResponse;
+using etcdserverpb::MemberListRequest;
+using etcdserverpb::MemberListResponse;
+using etcdserverpb::MemberRemoveRequest;
+using etcdserverpb::MemberRemoveResponse;
 using etcdserverpb::PutRequest;
 using etcdserverpb::PutResponse;
 using etcdserverpb::RangeRequest;
@ -76,8 +82,7 @@ class AsyncCampaignResponse : public etcdv3::V3Response {
 class AsyncDeleteResponse : public etcdv3::V3Response {
 public:
  AsyncDeleteResponse(){};
-  void ParseResponse(std::string const& key, bool prefix,
-                     DeleteRangeResponse& resp);
+  void ParseResponse(DeleteRangeResponse& resp);
 };

 class AsyncHeadResponse : public etcdv3::V3Response {
@ -104,6 +109,24 @@ class AsyncLeaseKeepAliveResponse : public etcdv3::V3Response {
  void ParseResponse(LeaseKeepAliveResponse& resp);
 };

+class AsyncMemberAddResponse : public etcdv3::V3Response {
+ public:
+  AsyncMemberAddResponse(){};
+  void ParseResponse(MemberAddResponse& resp);
+};
+
+class AsyncMemberListResponse : public etcdv3::V3Response {
+ public:
+  AsyncMemberListResponse(){};
+  void ParseResponse(MemberListResponse& resp);
+};
+
+class AsyncMemberRemoveResponse : public etcdv3::V3Response {
+ public:
+  AsyncMemberRemoveResponse(){};
+  void ParseResponse(MemberRemoveResponse& resp);
+};
+
 class AsyncLeaseLeasesResponse : public etcdv3::V3Response {
 public:
  AsyncLeaseLeasesResponse(){};
@ -162,7 +185,6 @@ class AsyncTxnResponse : public etcdv3::V3Response {
 public:
  AsyncTxnResponse(){};
  void ParseResponse(TxnResponse& resp);
-  void ParseResponse(std::string const& key, bool prefix, TxnResponse& resp);
 };

 class AsyncUnlockResponse : public etcdv3::V3Response {
@ -271,12 +293,44 @@ class AsyncLeaseKeepAliveAction : public etcdv3::Action {
      stream;

  LeaseKeepAliveRequest req;
-  bool isCancelled;
+  std::atomic_bool isCancelled;
  std::recursive_mutex protect_is_cancelled;

  friend class etcd::KeepAlive;
 };

+class AsyncAddMemberAction : public etcdv3::Action {
+ public:
+  AsyncAddMemberAction(etcdv3::ActionParameters&& params);
+  AsyncMemberAddResponse ParseResponse();
+
+ private:
+  MemberAddResponse reply;
+  std::unique_ptr<ClientAsyncResponseReader<MemberAddResponse>> response_reader;
+};
+
+class AsyncListMemberAction : public etcdv3::Action {
+ public:
+  AsyncListMemberAction(etcdv3::ActionParameters&& params);
+  AsyncMemberListResponse ParseResponse();
+
+ private:
+  MemberListResponse reply;
+  std::unique_ptr<ClientAsyncResponseReader<MemberListResponse>>
+      response_reader;
+};
+
+class AsyncRemoveMemberAction : public etcdv3::Action {
+ public:
+  AsyncRemoveMemberAction(etcdv3::ActionParameters&& params);
+  AsyncMemberRemoveResponse ParseResponse();
+
+ private:
+  MemberRemoveResponse reply;
+  std::unique_ptr<ClientAsyncResponseReader<MemberRemoveResponse>>
+      response_reader;
+};
+
 class AsyncLeaseLeasesAction : public etcdv3::Action {
 public:
  AsyncLeaseLeasesAction(etcdv3::ActionParameters&& params);
@ -332,7 +386,7 @@ class AsyncObserveAction : public etcdv3::Action {
  LeaderResponse reply;
  std::unique_ptr<ClientAsyncReader<LeaderResponse>> response_reader;
  std::atomic_bool isCancelled;
-  std::mutex protect_is_cancalled;
+  std::mutex protect_is_cancelled;
 };

 class AsyncProclaimAction : public etcdv3::Action {
--- a/etcd/v3/Member.hpp
+++ b/etcd/v3/Member.hpp
@ -0,0 +1,33 @@
+#ifndef __V3_ETCDV3MEMBERS_HPP__
+#define __V3_ETCDV3MEMBERS_HPP__
+
+#include <cstdint>
+#include <string>
+#include <vector>
+using namespace std;
+
+namespace etcdv3 {
+class Member {
+ public:
+  Member();
+
+  void set_id(uint64_t const& id);
+  uint64_t const& get_id() const;
+  void set_name(std::string const& name);
+  std::string const& get_name() const;
+  void set_peerURLs(std::vector<std::string> const& peerURLs);
+  std::vector<std::string> const& get_peerURLs() const;
+  void set_clientURLs(std::vector<std::string> const& clientURLs);
+  std::vector<std::string> const& get_clientURLs() const;
+  void set_learner(bool isLearner);
+  bool get_learner() const;
+
+ private:
+  uint64_t id;
+  std::string name;
+  std::vector<std::string> peerURLs;
+  std::vector<std::string> clientURLs;
+  bool isLearner;
+};
+}  // namespace etcdv3
+#endif
--- a/etcd/v3/Transaction.hpp
+++ b/etcd/v3/Transaction.hpp
@ -28,38 +28,194 @@ enum class CompareTarget {
 class Transaction {
 public:
  Transaction();
-  Transaction(std::string const&);
-  virtual ~Transaction();
+  ~Transaction();

-  // Set a new key for different comparisons and /put/get/delete requests.
-  void reset_key(std::string const& newkey);
+  union Value {
+    int64_t version;
+    int64_t create_revision;
+    int64_t mod_revision;
+    std::string value;
+    int64_t lease;
+  };

-  void init_compare(CompareResult, CompareTarget);
-  void init_compare(std::string const& old_value, CompareResult, CompareTarget);
-  void init_compare(int64_t old_value, CompareResult, CompareTarget);
+  void add_compare(std::string const& key, CompareTarget const& target,
+                   CompareResult const& result, Value const& target_value,
+                   std::string const& range_end = "");

-  void setup_basic_failure_operation(std::string const& key);
-  void setup_set_failure_operation(std::string const& key,
-                                   std::string const& value, int64_t leaseid);
-  void setup_basic_create_sequence(std::string const& key,
-                                   std::string const& value, int64_t leaseid);
-  void setup_compare_and_swap_sequence(std::string const& valueToSwap,
-                                       int64_t leaseid);
-  void setup_delete_sequence(std::string const& key,
-                             std::string const& range_end, bool recursive);
-  void setup_delete_failure_operation(std::string const& key,
-                                      std::string const& range_end,
-                                      bool recursive);
-  void setup_compare_and_delete_operation(std::string const& key);
+  void add_compare_version(std::string const& key, int64_t const& version,
+                           std::string const& range_end = "");
+  void add_compare_version(std::string const& key, CompareResult const& result,
+                           int64_t const& version,
+                           std::string const& range_end = "");
+  void add_compare_create(std::string const& key,
+                          int64_t const& create_revision,
+                          std::string const& range_end = "");
+  void add_compare_create(std::string const& key, CompareResult const& result,
+                          int64_t const& create_revision,
+                          std::string const& range_end = "");
+  void add_compare_mod(std::string const& key, int64_t const& mod_revision,
+                       std::string const& range_end = "");
+  void add_compare_mod(std::string const& key, CompareResult const& result,
+                       int64_t const& mod_revision,
+                       std::string const& range_end = "");
+  void add_compare_value(std::string const& key, std::string const& value,
+                         std::string const& range_end = "");
+  void add_compare_value(std::string const& key, CompareResult const& result,
+                         std::string const& value,
+                         std::string const& range_end = "");
+  void add_compare_lease(std::string const& key, int64_t const& lease,
+                         std::string const& range_end = "");
+  void add_compare_lease(std::string const& key, CompareResult const& result,
+                         int64_t const& lease,
+                         std::string const& range_end = "");
+
+  void add_success_range(std::string const& key,
+                         std::string const& range_end = "",
+                         bool const recursive = false, const int64_t limit = 0);
+  void add_success_put(std::string const& key, std::string const& value,
+                       int64_t const leaseid = 0, const bool prev_kv = false);
+  void add_success_delete(std::string const& key,
+                          std::string const& range_end = "",
+                          bool const recursive = false,
+                          const bool prev_kv = false);
+  void add_success_txn(const std::shared_ptr<Transaction> txn);
+
+  void add_failure_range(std::string const& key,
+                         std::string const& range_end = "",
+                         bool const recursive = false, const int64_t limit = 0);
+  void add_failure_put(std::string const& key, std::string const& value,
+                       int64_t const leaseid = 0, const bool prev_kv = false);
+  void add_failure_delete(std::string const& key,
+                          std::string const& range_end = "",
+                          bool const recursive = false,
+                          const bool prev_kv = false);
+  void add_failure_txn(const std::shared_ptr<Transaction> txn);
+
+  /**
+   * @brief Compare, and create if succeed. If failed, the response will
+   *        contains the previous value in "values()" field.
+   */
+  void setup_compare_and_create(std::string const& key,
+                                std::string const& prev_value,
+                                std::string const& create_key,
+                                std::string const& value,
+                                int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, or create if failed. If failed, the response will contains
+   *        the previous value in "values()" field.
+   */
+  void setup_compare_or_create(std::string const& key,
+                               std::string const& prev_value,
+                               std::string const& create_key,
+                               std::string const& value,
+                               int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, and swap if succeed. If failed, the response will contains
+   *        the previous value in "values()" field.
+   */
+  void setup_compare_and_swap(std::string const& key,
+                              std::string const& prev_value,
+                              std::string const& value,
+                              int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, and swap if failed. If failed, the response will contains
+   *        the previous value in "values()" field.
+   */
+  void setup_compare_or_swap(std::string const& key,
+                             std::string const& prev_value,
+                             std::string const& value,
+                             int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, and delete if succeed. If failed, the response will
+   *        contains the previous value in "values()" field.
+   */
+  void setup_compare_and_delete(std::string const& key,
+                                std::string const& prev_value,
+                                std::string const& delete_key,
+                                std::string const& range_end = "",
+                                const bool recursive = false);
+
+  /**
+   * @brief Compare, or delete if failed. If failed, the response will contains
+   * the previous value in "values()" field.
+   */
+  void setup_compare_or_delete(std::string const& key,
+                               std::string const& prev_value,
+                               std::string const& delete_key,
+                               std::string const& range_end = "",
+                               const bool recursive = false);
+
+  /**
+   * @brief Compare, and create if succeed. If failed, the response will
+   *        contains the previous value in "values()" field.
+   */
+  void setup_compare_and_create(std::string const& key,
+                                const int64_t prev_revision,
+                                std::string const& create_key,
+                                std::string const& value,
+                                int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, or create if failed. If failed, the response will contains
+   *        the previous value in "values()" field.
+   */
+  void setup_compare_or_create(std::string const& key,
+                               const int64_t prev_revision,
+                               std::string const& create_key,
+                               std::string const& value,
+                               int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, and swap if succeed. If failed, the response will contains
+   *        the previous value in "values()" field.
+   */
+  void setup_compare_and_swap(std::string const& key,
+                              const int64_t prev_revision,
+                              std::string const& value,
+                              int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, and swap if failed. If failed, the response will contains
+   *        the previous value in "values()" field.
+   */
+  void setup_compare_or_swap(std::string const& key,
+                             const int64_t prev_revision,
+                             std::string const& value,
+                             int64_t const leaseid = 0);
+
+  /**
+   * @brief Compare, and delete if succeed. If failed, the response will
+   *        contains the previous value in "values()" field.
+   */
+  void setup_compare_and_delete(std::string const& key,
+                                const int64_t prev_revision,
+                                std::string const& delete_key,
+                                std::string const& range_end = "",
+                                const bool recursive = false);
+
+  /**
+   * @brief Compare, or delete if failed. If failed, the response will contains
+   * the previous value in "values()" field.
+   */
+  void setup_compare_or_delete(std::string const& key,
+                               const int64_t prev_revision,
+                               std::string const& delete_key,
+                               std::string const& range_end = "",
+                               const bool recursive = false);
+
+  // Keep for backwards compatibility.

  // update without `get` and no `prev_kv` returned
  void setup_put(std::string const& key, std::string const& value);
  void setup_delete(std::string const& key);
+  void setup_delete(std::string const& key, std::string const& range_end,
+                    const bool recursive = false);

  std::shared_ptr<etcdserverpb::TxnRequest> txn_request;
-
- private:
-  std::string key;
 };

 }  // namespace etcdv3
--- a/etcd/v3/V3Response.hpp
+++ b/etcd/v3/V3Response.hpp
@ -6,6 +6,7 @@
 #include "proto/v3election.pb.h"

 #include "etcd/v3/KeyValue.hpp"
+#include "etcd/v3/Member.hpp"

 namespace etcdv3 {
 class V3Response {
@ -36,6 +37,7 @@ class V3Response {
  uint64_t get_member_id() const;
  uint64_t get_raft_term() const;
  std::vector<int64_t> const& get_leases() const;
+  std::vector<etcdv3::Member> const& get_members() const;

 protected:
  int error_code;
@ -59,6 +61,8 @@ class V3Response {

  // for lease list
  std::vector<int64_t> leases;
+  // for member list
+  std::vector<etcdv3::Member> members;
 };
 }  // namespace etcdv3
 #endif
--- a/etcd/v3/action_constants.hpp
+++ b/etcd/v3/action_constants.hpp
@ -23,6 +23,10 @@ extern char const* LEASEKEEPALIVE;
 extern char const* LEASETIMETOLIVE;
 extern char const* LEASELEASES;

+extern char const* ADDMEMBER;
+extern char const* LISTMEMBER;
+extern char const* REMOVEMEMBER;
+
 extern char const* CAMPAIGN_ACTION;
 extern char const* PROCLAIM_ACTION;
 extern char const* LEADER_ACTION;
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@ -19,35 +19,50 @@ file(GLOB_RECURSE CPP_CLIENT_CORE_SRC

 add_library(etcd-cpp-api-core-objects OBJECT ${CPP_CLIENT_CORE_SRC} ${PROTOBUF_GENERATES})
 use_cxx(etcd-cpp-api-core-objects)
+set_exceptions(etcd-cpp-api-core-objects)
 add_dependencies(etcd-cpp-api-core-objects protobuf_generates)
 include_generated_protobuf_files(etcd-cpp-api-core-objects)
 target_link_libraries(etcd-cpp-api-core-objects PUBLIC
-                      ${PROTOBUF_LIBRARIES}
                      ${OPENSSL_LIBRARIES}
                      ${GRPC_LIBRARIES}
 )
+if(TARGET protobuf::libprotobuf)
+    target_link_libraries(etcd-cpp-api-core-objects PUBLIC protobuf::libprotobuf)
+else()
+    target_link_libraries(etcd-cpp-api-core-objects PUBLIC ${PROTOBUF_LIBRARIES})
+endif()

 if(BUILD_ETCD_CORE_ONLY)
    # add the core library, includes the sycnhronous client only
    add_library(etcd-cpp-api-core $<TARGET_OBJECTS:etcd-cpp-api-core-objects>)
    use_cxx(etcd-cpp-api-core)
+    set_exceptions(etcd-cpp-api-core)
    target_link_libraries(etcd-cpp-api-core PUBLIC
-                         ${PROTOBUF_LIBRARIES}
                          ${OPENSSL_LIBRARIES}
                          ${GRPC_LIBRARIES}
    )
+    if(TARGET protobuf::libprotobuf)
+        target_link_libraries(etcd-cpp-api-core PUBLIC protobuf::libprotobuf)
+    else()
+        target_link_libraries(etcd-cpp-api-core PUBLIC ${PROTOBUF_LIBRARIES})
+    endif()
    include_generated_protobuf_files(etcd-cpp-api-core)
 else()
    # add the client with asynchronus client
    add_library(etcd-cpp-api $<TARGET_OBJECTS:etcd-cpp-api-core-objects>
                            "${CMAKE_CURRENT_SOURCE_DIR}/Client.cpp")
    use_cxx(etcd-cpp-api)
+    set_exceptions(etcd-cpp-api)
    target_link_libraries(etcd-cpp-api PUBLIC
                          ${CPPREST_LIB}  # n.b.: the asynchronous client requires pplx in cpprestsdk
-                          ${PROTOBUF_LIBRARIES}
                          ${OPENSSL_LIBRARIES}
                          ${GRPC_LIBRARIES}
    )
+    if(TARGET protobuf::libprotobuf)
+        target_link_libraries(etcd-cpp-api PUBLIC protobuf::libprotobuf)
+    else()
+        target_link_libraries(etcd-cpp-api PUBLIC ${PROTOBUF_LIBRARIES})
+    endif()
    include_generated_protobuf_files(etcd-cpp-api)
 endif()

--- a/src/Client.cpp
+++ b/src/Client.cpp
@ -231,61 +231,15 @@ pplx::task<etcd::Response> etcd::Client::get(std::string const& key,

 pplx::task<etcd::Response> etcd::Client::set(std::string const& key,
                                             std::string const& value,
-                                             int ttl) {
-  if (ttl > 0) {
-    return this->leasegrant(ttl).then(
-        [this, key, value](pplx::task<etcd::Response> const& task) {
-          auto resp = task.get();
-          if (resp.error_code() == 0) {
+                                             const int64_t leaseid) {
  return etcd::detail::asyncify(
-                static_cast<responser_t<etcdv3::AsyncSetAction>>(
-                    Response::create),
-                this->client->set_internal(key, value, resp.value().lease()));
-          } else {
-            return pplx::task_from_result(resp);
-          }
-        });
-  } else {
-    return etcd::detail::asyncify(
-        static_cast<responser_t<etcdv3::AsyncSetAction>>(Response::create),
-        this->client->set_internal(key, value, 0));
-  }
-}
-
-pplx::task<etcd::Response> etcd::Client::set(std::string const& key,
-                                             std::string const& value,
-                                             int64_t leaseid) {
-  return etcd::detail::asyncify(
-      static_cast<responser_t<etcdv3::AsyncSetAction>>(Response::create),
-      this->client->set_internal(key, value, leaseid));
+      static_cast<responser_t<etcdv3::AsyncPutAction>>(Response::create),
+      this->client->put_internal(key, value, leaseid));
 }

 pplx::task<etcd::Response> etcd::Client::add(std::string const& key,
                                             std::string const& value,
-                                             int ttl) {
-  if (ttl > 0) {
-    return this->leasegrant(ttl).then(
-        [this, key, value](pplx::task<etcd::Response> const& task) {
-          auto resp = task.get();
-          if (resp.error_code() == 0) {
-            return etcd::detail::asyncify(
-                static_cast<responser_t<etcdv3::AsyncSetAction>>(
-                    Response::create),
-                this->client->add_internal(key, value, resp.value().lease()));
-          } else {
-            return pplx::task_from_result(resp);
-          }
-        });
-  } else {
-    return etcd::detail::asyncify(
-        static_cast<responser_t<etcdv3::AsyncSetAction>>(Response::create),
-        this->client->add_internal(key, value, 0));
-  }
-}
-
-pplx::task<etcd::Response> etcd::Client::add(std::string const& key,
-                                             std::string const& value,
-                                             int64_t leaseid) {
+                                             const int64_t leaseid) {
  return etcd::detail::asyncify(
      static_cast<responser_t<etcdv3::AsyncSetAction>>(Response::create),
      this->client->add_internal(key, value, leaseid));
@ -298,33 +252,17 @@ pplx::task<etcd::Response> etcd::Client::put(std::string const& key,
      this->client->put_internal(key, value));
 }

-pplx::task<etcd::Response> etcd::Client::modify(std::string const& key,
+pplx::task<etcd::Response> etcd::Client::put(std::string const& key,
                                             std::string const& value,
-                                                int ttl) {
-  if (ttl > 0) {
-    return this->leasegrant(ttl).then(
-        [this, key, value](pplx::task<etcd::Response> const& task) {
-          auto resp = task.get();
-          if (resp.error_code() == 0) {
+                                             const int64_t leaseId) {
  return etcd::detail::asyncify(
-                static_cast<responser_t<etcdv3::AsyncUpdateAction>>(
-                    Response::create),
-                this->client->modify_internal(key, value,
-                                              resp.value().lease()));
-          } else {
-            return pplx::task_from_result(resp);
-          }
-        });
-  } else {
-    return etcd::detail::asyncify(
-        static_cast<responser_t<etcdv3::AsyncUpdateAction>>(Response::create),
-        this->client->modify_internal(key, value, 0));
-  }
+      static_cast<responser_t<etcdv3::AsyncPutAction>>(Response::create),
+      this->client->put_internal(key, value, leaseId));
 }

 pplx::task<etcd::Response> etcd::Client::modify(std::string const& key,
                                                std::string const& value,
-                                                int64_t leaseid) {
+                                                const int64_t leaseid) {
  return etcd::detail::asyncify(
      static_cast<responser_t<etcdv3::AsyncUpdateAction>>(Response::create),
      this->client->modify_internal(key, value, leaseid));
@ -333,78 +271,25 @@ pplx::task<etcd::Response> etcd::Client::modify(std::string const& key,
 pplx::task<etcd::Response> etcd::Client::modify_if(std::string const& key,
                                                   std::string const& value,
                                                   std::string const& old_value,
-                                                   int ttl) {
-  if (ttl > 0) {
-    return this->leasegrant(ttl).then(
-        [this, key, value, old_value](pplx::task<etcd::Response> const& task) {
-          auto resp = task.get();
-          if (resp.error_code() == 0) {
+                                                   const int64_t leaseid) {
  return etcd::detail::asyncify(
      static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
          Response::create),
-                this->client->modify_if_internal(
-                    key, value, 0, old_value, resp.value().lease(),
-                    etcdv3::AtomicityType::PREV_VALUE));
-          } else {
-            return pplx::task_from_result(resp);
-          }
-        });
-  } else {
-    return etcd::detail::asyncify(
-        static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
-            Response::create),
-        this->client->modify_if_internal(key, value, 0, old_value, 0,
-                                         etcdv3::AtomicityType::PREV_VALUE));
-  }
-}
-
-pplx::task<etcd::Response> etcd::Client::modify_if(std::string const& key,
-                                                   std::string const& value,
-                                                   std::string const& old_value,
-                                                   int64_t leaseid) {
-  return etcd::detail::asyncify(
-      static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
-          Response::create),
-      this->client->modify_if_internal(key, value, 0, old_value, leaseid,
-                                       etcdv3::AtomicityType::PREV_VALUE));
-}
-
-pplx::task<etcd::Response> etcd::Client::modify_if(std::string const& key,
-                                                   std::string const& value,
-                                                   int64_t old_index, int ttl) {
-  if (ttl > 0) {
-    return this->leasegrant(ttl).then(
-        [this, key, value, old_index](pplx::task<etcd::Response> const& task) {
-          auto resp = task.get();
-          if (resp.error_code() == 0) {
-            return etcd::detail::asyncify(
-                static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
-                    Response::create),
-                this->client->modify_if_internal(
-                    key, value, old_index, "", resp.value().lease(),
-                    etcdv3::AtomicityType::PREV_INDEX));
-          } else {
-            return pplx::task_from_result(resp);
-          }
-        });
-  } else {
-    return etcd::detail::asyncify(
-        static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
-            Response::create),
-        this->client->modify_if_internal(key, value, old_index, "", 0,
-                                         etcdv3::AtomicityType::PREV_INDEX));
-  }
+      this->client->modify_if_internal(key, value, 0, old_value,
+                                       etcdv3::AtomicityType::PREV_VALUE,
+                                       leaseid));
 }

 pplx::task<etcd::Response> etcd::Client::modify_if(std::string const& key,
                                                   std::string const& value,
                                                   int64_t old_index,
-                                                   int64_t leaseid) {
+                                                   const int64_t leaseid) {
  return etcd::detail::asyncify(
      static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
          Response::create),
-      this->client->modify_if_internal(key, value, old_index, "", leaseid,
-                                       etcdv3::AtomicityType::PREV_INDEX));
+      this->client->modify_if_internal(key, value, old_index, "",
+                                       etcdv3::AtomicityType::PREV_INDEX,
+                                       leaseid));
 }

 pplx::task<etcd::Response> etcd::Client::rm(std::string const& key) {
@ -609,6 +494,27 @@ pplx::task<etcd::Response> etcd::Client::leases() {
      this->client->leases_internal());
 }

+pplx::task<etcd::Response> etcd::Client::add_member(
+    std::string const& peer_urls, bool is_learner) {
+  return etcd::detail::asyncify(
+      static_cast<responser_t<etcdv3::AsyncAddMemberAction>>(Response::create),
+      this->client->add_member_internal(peer_urls, is_learner));
+}
+
+pplx::task<etcd::Response> etcd::Client::list_member() {
+  return etcd::detail::asyncify(
+      static_cast<responser_t<etcdv3::AsyncListMemberAction>>(Response::create),
+      this->client->list_member_internal());
+}
+
+pplx::task<etcd::Response> etcd::Client::remove_member(
+    const uint64_t member_id) {
+  return etcd::detail::asyncify(
+      static_cast<responser_t<etcdv3::AsyncRemoveMemberAction>>(
+          Response::create),
+      this->client->remove_member_internal(member_id));
+}
+
 pplx::task<etcd::Response> etcd::Client::lock(std::string const& key) {
  static const int DEFAULT_LEASE_TTL_FOR_LOCK =
      10;  // see also etcd::SyncClient::lock
--- a/src/KeepAlive.cpp
+++ b/src/KeepAlive.cpp
@ -1,4 +1,5 @@
 #include <chrono>
+#include <iostream>
 #include <ratio>

 #include "etcd/KeepAlive.hpp"
@ -28,6 +29,10 @@ etcd::KeepAlive::KeepAlive(SyncClient const& client, int ttl, int64_t lease_id)
      lease_id(lease_id),
      continue_next(true),
      grpc_timeout(client.get_grpc_timeout()) {
+  if (ttl > 0 && lease_id == 0) {
+    this->lease_id =
+        const_cast<SyncClient&>(client).leasegrant(ttl).value().lease();
+  }
  stubs.reset(new EtcdServerStubs{});
  stubs->leaseServiceStub = Lease::NewStub(client.grpc_channel());

@ -41,6 +46,7 @@ etcd::KeepAlive::KeepAlive(SyncClient const& client, int ttl, int64_t lease_id)

  stubs->call.reset(new etcdv3::AsyncLeaseKeepAliveAction(std::move(params)));
  refresh_task_ = std::thread([this]() {
+#ifndef _ETCD_NO_EXCEPTIONS
    try {
      // start refresh
      this->refresh();
@ -48,6 +54,12 @@ etcd::KeepAlive::KeepAlive(SyncClient const& client, int ttl, int64_t lease_id)
      // propagate the exception
      eptr_ = std::current_exception();
    }
+#else
+    const std::string err = this->refresh();
+    if (!err.empty()) {
+      eptr_ = std::make_exception_ptr(std::runtime_error(err));
+    }
+#endif
  });
 }

@ -68,7 +80,7 @@ etcd::KeepAlive::KeepAlive(
    std::function<void(std::exception_ptr)> const& handler, int ttl,
    int64_t lease_id, std::string const& target_name_override)
    : KeepAlive(SyncClient(address, ca, cert, privkey, target_name_override),
-                ttl, lease_id) {}
+                handler, ttl, lease_id) {}

 etcd::KeepAlive::KeepAlive(
    SyncClient const& client,
@ -79,6 +91,10 @@ etcd::KeepAlive::KeepAlive(
      lease_id(lease_id),
      continue_next(true),
      grpc_timeout(client.get_grpc_timeout()) {
+  if (ttl > 0 && lease_id == 0) {
+    this->lease_id =
+        const_cast<SyncClient&>(client).leasegrant(ttl).value().lease();
+  }
  stubs.reset(new EtcdServerStubs{});
  stubs->leaseServiceStub = Lease::NewStub(client.grpc_channel());

@ -90,15 +106,22 @@ etcd::KeepAlive::KeepAlive(

  stubs->call.reset(new etcdv3::AsyncLeaseKeepAliveAction(std::move(params)));
  refresh_task_ = std::thread([this]() {
+#ifndef _ETCD_NO_EXCEPTIONS
    try {
      // start refresh
      this->refresh();
    } catch (...) {
-      // propogate the exception
+      // propagate the exception
      eptr_ = std::current_exception();
-      if (handler_) {
-        handler_(eptr_);
    }
+#else
+    const std::string err = this->refresh();
+    if (!err.empty()) {
+      eptr_ = std::make_exception_ptr(std::runtime_error(err));
+    }
+#endif
+    if (eptr_ && handler_) {
+      handler_(eptr_);
    }
  });
 }
@ -140,6 +163,7 @@ void etcd::KeepAlive::Check() {
    std::rethrow_exception(eptr_);
  }
  // issue an refresh to make sure it still alive
+#ifndef _ETCD_NO_EXCEPTIONS
  try {
    this->refresh_once();
  } catch (...) {
@ -149,19 +173,35 @@ void etcd::KeepAlive::Check() {
    // propagate the exception, as we throw in `Check()`, the `handler` won't be
    // touched
    eptr_ = std::current_exception();
-    if (handler_) {
+  }
+#else
+  const std::string err = this->refresh_once();
+  if (!err.empty()) {
+    // run canceller first
+    this->Cancel();
+
+    // propagate the exception, as we throw in `Check()`, the `handler` won't be
+    // touched
+    eptr_ = std::make_exception_ptr(std::runtime_error(err));
+  }
+#endif
+  if (eptr_ && handler_) {
    handler_(eptr_);
  }

+#ifndef _ETCD_NO_EXCEPTIONS
+  if (eptr_) {
    // rethrow in `Check()` to keep the consistent semantics
    std::rethrow_exception(eptr_);
  }
+#endif
+  return;
 }

-void etcd::KeepAlive::refresh() {
+std::string etcd::KeepAlive::refresh() {
  while (true) {
    if (!continue_next.load()) {
-      return;
+      return std::string{};
    }
    // minimal resolution: 1 second
    int keepalive_ttl = std::max(ttl - 1, 1);
@ -169,29 +209,50 @@ void etcd::KeepAlive::refresh() {
      std::unique_lock<std::mutex> lock(mutex_for_refresh_);
      if (cv_for_refresh_.wait_for(lock, std::chrono::seconds(keepalive_ttl)) ==
          std::cv_status::no_timeout) {
-        return;
+        if (!continue_next.load()) {
+          return std::string{};
+        }
+#ifndef NDEBUG
+        std::cerr
+            << "[warn] awaked from condition_variable but continue_next is "
+               "not set, maybe due to clock drift."
+            << std::endl;
+#endif
      }
    }

    // execute refresh
-    this->refresh_once();
+    const std::string err = this->refresh_once();
+    if (!err.empty()) {
+      return err;
    }
+  }
+  return std::string{};
 }

-void etcd::KeepAlive::refresh_once() {
+std::string etcd::KeepAlive::refresh_once() {
  std::lock_guard<std::mutex> scope_lock(mutex_for_refresh_);
  if (!continue_next.load()) {
-    return;
+    return std::string{};
  }
  this->stubs->call->mutable_parameters().grpc_timeout = this->grpc_timeout;
  auto resp = this->stubs->call->Refresh();
  if (!resp.is_ok()) {
-    throw std::runtime_error("Failed to refresh lease: error code: " +
+    const std::string err = "Failed to refresh lease: error code: " +
                            std::to_string(resp.error_code()) +
-                             ", message: " + resp.error_message());
+                            ", message: " + resp.error_message();
+#ifndef _ETCD_NO_EXCEPTIONS
+    throw std::runtime_error(err);
+#endif
+    return err;
  }
  if (resp.value().ttl() == 0) {
-    throw std::out_of_range(
-        "Failed to refresh lease due to expiration: the new TTL is 0.");
+    const std::string err =
+        "Failed to refresh lease due to expiration: the new TTL is 0.";
+#ifndef _ETCD_NO_EXCEPTIONS
+    throw std::out_of_range(err);
+#endif
+    return err;
  }
+  return std::string{};
 }
--- a/src/Response.cpp
+++ b/src/Response.cpp
@ -25,6 +25,7 @@ etcd::Response::Response(const etcd::Response& response) {
  this->_raft_term = response._raft_term;

  this->_leases = response._leases;
+  this->_members = response._members;
 }

 etcd::Response::Response(const etcdv3::V3Response& reply,
@ -39,6 +40,7 @@ etcd::Response::Response(const etcdv3::V3Response& reply,
      _values.push_back(Value(val[index]));
      _keys.push_back(val[index].kvs.key());
    }
+    _value = Value(reply.get_values()[0]);
  } else {
    _value = Value(reply.get_value());
  }
@ -63,6 +65,8 @@ etcd::Response::Response(const etcdv3::V3Response& reply,

  // lease list
  this->_leases = reply.get_leases();
+  // member list
+  this->_members = reply.get_members();
 }

 etcd::Response::Response(int error_code, std::string const& error_message)
@ -130,3 +134,7 @@ uint64_t etcd::Response::raft_term() const { return this->_raft_term; }
 std::vector<int64_t> const& etcd::Response::leases() const {
  return this->_leases;
 }
+
+std::vector<etcdv3::Member> const& etcd::Response::members() const {
+  return this->_members;
+}
--- a/src/SyncClient.cpp
+++ b/src/SyncClient.cpp
@ -4,6 +4,11 @@
 #define NOMINMAX
 #endif

+#ifdef __ANDROID__
+#include <netinet/in.h>
+#endif
+
+#include <arpa/inet.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>
@ -33,6 +38,7 @@
 #include <grpc++/grpc++.h>
 #include <grpc++/security/credentials.h>
 #include <grpc++/support/status_code_enum.h>
+#include <grpc/grpc.h>  // for grpc_lame_client_channel_create()

 #include "proto/rpc.grpc.pb.h"
 #include "proto/v3election.grpc.pb.h"
@ -45,6 +51,22 @@
 #include "etcd/v3/Transaction.hpp"
 #include "etcd/v3/action_constants.hpp"

+namespace grpc {
+// forward declaration for compatibility with older grpc versions
+std::shared_ptr<Channel> CreateChannelInternal(
+    const std::string& host, grpc_channel* c_channel,
+#if defined(WITH_GRPC_CREATE_CHANNEL_INTERNAL_UNIQUE_POINTER)
+    std::unique_ptr<std::vector<
+        std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>>
+        interceptor_creators
+#else
+    std::vector<
+        std::unique_ptr<grpc::experimental::ClientInterceptorFactoryInterface>>
+        interceptor_creators
+#endif
+);
+}  // namespace grpc
+
 namespace etcd {
 namespace detail {

@ -66,7 +88,7 @@ static void string_split(std::vector<std::string>& dests,
 }

 static std::string string_join(std::vector<std::string> const& srcs,
-                               std::string const sep) {
+                               std::string const& sep) {
  std::stringstream ss;
  if (!srcs.empty()) {
    ss << srcs[0];
@ -78,19 +100,32 @@ static std::string string_join(std::vector<std::string> const& srcs,
 }

 static bool dns_resolve(std::string const& target,
-                        std::vector<std::string>& endpoints) {
-  struct addrinfo hints = {}, *addrs;
-  hints.ai_family = AF_INET;
-  hints.ai_socktype = SOCK_STREAM;
-  hints.ai_protocol = IPPROTO_TCP;
-
+                        std::vector<std::string>& endpoints, bool ipv4 = true) {
  std::vector<std::string> target_parts;
-  string_split(target_parts, target, ":");
-  if (target_parts.size() != 2) {
-    std::cerr << "warn: invalid URL: " << target << std::endl;
+  bool ipv6_url{false};
+  {
+    size_t rindex = target.rfind(':');
+    if (rindex == target.npos) {
+#ifndef NDEBUG
+      std::cerr << "[warn] invalid URL: " << target << ", expects 'host:port'"
+                << std::endl;
+#endif
      return false;
    }

+    std::string host(target.substr(0, rindex));
+
+    // host format is [ipv6]
+    if (!ipv4 && !host.empty() && host[0] == '[' &&
+        host[host.size() - 1] == ']') {
+      host = target.substr(1, rindex - 2);
+      ipv6_url = true;
+    }
+
+    target_parts.push_back(host);
+    target_parts.push_back(target.substr(rindex + 1));
+  }
+
 #if defined(_WIN32)
  {
    // Use the MAKEWORD(lowbyte, highbyte) macro declared in Windef.h.
@ -100,26 +135,61 @@ static bool dns_resolve(std::string const& target,
    int err = WSAStartup(wVersionRequested, &wsaData);
    if (err != 0) {
      // Tell the user that we could not find a usable Winsock DLL.
-      std::cerr << "WSAStartup failed with error: %d" << err << std::endl;
+#ifndef NDEBUG
+      std::cerr << "[warn] WSAStartup failed with error: %d" << err
+                << std::endl;
+#endif
      return false;
    }
  }
 #endif

+  if (ipv6_url) {
+    // check valid ipv6
+    struct sockaddr_in6 sa6;
+    if (inet_pton(AF_INET6, target_parts[0].c_str(), &(sa6.sin6_addr)) == 1) {
+      endpoints.emplace_back(target);
+      return true;
+    }
+    return false;
+  }
+
+  struct addrinfo hints = {}, *addrs;
+  hints.ai_family = ipv4 ? AF_INET : AF_INET6;
+  hints.ai_socktype = SOCK_STREAM;
+  hints.ai_protocol = IPPROTO_TCP;
+
  int r = getaddrinfo(target_parts[0].c_str(), target_parts[1].c_str(), &hints,
                      &addrs);
  if (r != 0) {
-    std::cerr << "warn: getaddrinfo() failed for endpoint " << target
-              << " with error: " << r << std::endl;
+#ifndef NDEBUG
+    std::cerr << "[warn] getaddrinfo() as " << (ipv4 ? "ipv4" : "ipv6")
+              << " failed for endpoint " << target << " with error: " << r
+              << ", " << strerror(errno) << std::endl;
+#endif
    return false;
  }

  char host[16] = {'\0'};
  for (struct addrinfo* addr = addrs; addr != nullptr; addr = addr->ai_next) {
+    if (addr->ai_family != AF_INET && addr->ai_family != AF_INET6) {
+      continue;
+    }
    memset(host, '\0', sizeof(host));
-    getnameinfo(addr->ai_addr, addr->ai_addrlen, host, sizeof(host), NULL, 0,
-                NI_NUMERICHOST);
-    endpoints.emplace_back(std::string(host) + ":" + target_parts[1]);
+    int r = getnameinfo(addr->ai_addr, addr->ai_addrlen, host, sizeof(host),
+                        NULL, 0, NI_NUMERICHOST);
+    if (r != 0) {
+#ifndef NDEBUG
+      std::cerr << "[warn] getnameinfo() failed for endpoint " << target
+                << " with error: " << r << ", " << strerror(errno) << std::endl;
+#endif
+      continue;
+    }
+    std::string host_string = host;
+    if (addr->ai_family == AF_INET6) {
+      host_string = "[" + host_string + "]";
+    }
+    endpoints.emplace_back(host_string + ":" + target_parts[1]);
  }
  freeaddrinfo(addrs);
  return true;
@ -128,24 +198,32 @@ static bool dns_resolve(std::string const& target,
 const std::string strip_and_resolve_addresses(std::string const& address) {
  std::vector<std::string> addresses;
  string_split(addresses, address, ",;");
-  std::string stripped_address;
+  std::string stripped_v4_address, stripped_v6_address;
  {
-    std::vector<std::string> stripped_addresses;
+    std::vector<std::string> stripped_v4_addresses, stripped_v6_addresses;
    std::string substr("://");
    for (auto const& addr : addresses) {
      std::string::size_type idx = addr.find(substr);
      std::string target =
          idx == std::string::npos ? addr : addr.substr(idx + substr.length());
-      etcd::detail::dns_resolve(target, stripped_addresses);
+      etcd::detail::dns_resolve(target, stripped_v4_addresses, true);
+      etcd::detail::dns_resolve(target, stripped_v6_addresses, false);
    }
-    stripped_address = string_join(stripped_addresses, ",");
+    stripped_v4_address = string_join(stripped_v4_addresses, ",");
+    stripped_v6_address = string_join(stripped_v6_addresses, ",");
  }
-  return "ipv4:///" + stripped_address;
+  // prefer resolved ipv4 addresses
+  if (!stripped_v4_address.empty()) {
+    return "ipv4:///" + stripped_v4_address;
+  }
+  if (!stripped_v6_address.empty()) {
+    return "ipv6:///" + stripped_v6_address;
+  }
+  return std::string{};
 }

-const bool authenticate(std::shared_ptr<grpc::Channel> const& channel,
-                        std::string const& username,
-                        std::string const& password,
+bool authenticate(std::shared_ptr<grpc::Channel> const& channel,
+                  std::string const& username, std::string const& password,
                  std::string& token_or_message) {
  // run a round of auth
  auto auth_stub = etcdserverpb::Auth::NewStub(channel);
@ -172,10 +250,12 @@ static std::string read_from_file(std::string const& filename) {
    file.close();
    return ss.str();
  } else {
-    std::cerr << "[ERROR] failed to load given file '" << filename << "', "
+#ifndef NDEBUG
+    std::cerr << "[error] failed to load given file '" << filename << "', "
              << strerror(errno) << std::endl;
-  }
+#endif
    return std::string{};
+  }
 }

 static grpc::SslCredentialsOptions make_ssl_credentials(
@ -192,6 +272,33 @@ std::unique_ptr<T> make_unique_ptr(Args&&... args) {
  return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
 }

+static std::shared_ptr<grpc::Channel> create_grpc_channel(
+    const std::string& address,
+    const std::shared_ptr<grpc::ChannelCredentials> creds,
+    const grpc::ChannelArguments& grpc_args) {
+  const std::string addresses =
+      etcd::detail::strip_and_resolve_addresses(address);
+#ifndef NDEBUG
+  std::cerr << "[debug] resolved addresses: " << addresses << std::endl;
+#endif
+  if (addresses.empty() || addresses == "ipv4:///" || addresses == "ipv6:///") {
+    // bypass grpc initialization to avoid noisy logs from grpc
+    return grpc::CreateChannelInternal(
+        "",
+        grpc_lame_client_channel_create(addresses.c_str(), GRPC_STATUS_INTERNAL,
+                                        "the target uri is not valid"),
+#if defined(WITH_GRPC_CREATE_CHANNEL_INTERNAL_UNIQUE_POINTER)
+        nullptr
+#else
+        std::vector<std::unique_ptr<
+            grpc::experimental::ClientInterceptorFactoryInterface>>()
+#endif
+    );
+  } else {
+    return grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  }
+}
+
 }  // namespace detail
 }  // namespace etcd

@ -235,7 +342,11 @@ class etcd::SyncClient::TokenAuthenticator {
        // auth
        if (!etcd::detail::authenticate(this->channel_, username_, password_,
                                        token_)) {
-          throw std::invalid_argument("Etcd authentication failed: " + token_);
+          // n.b.: no throw here as the failure of auth will be propagated
+          // to client when it is asked to issue requests.
+          //
+          // throw std::invalid_argument("Etcd authentication failed: " +
+          // token_);
        }
      }
    }
@ -253,6 +364,7 @@ void etcd::SyncClient::TokenAuthenticatorDeleter::operator()(
 struct etcd::SyncClient::EtcdServerStubs {
  std::unique_ptr<etcdserverpb::KV::Stub> kvServiceStub;
  std::unique_ptr<etcdserverpb::Watch::Stub> watchServiceStub;
+  std::unique_ptr<etcdserverpb::Cluster::Stub> clusterServiceStub;
  std::unique_ptr<etcdserverpb::Lease::Stub> leaseServiceStub;
  std::unique_ptr<v3lockpb::Lock::Stub> lockServiceStub;
  std::unique_ptr<v3electionpb::Election::Stub> electionServiceStub;
@ -268,21 +380,20 @@ void etcd::SyncClient::EtcdServerStubsDeleter::operator()(
 etcd::SyncClient::SyncClient(std::string const& address,
                             std::string const& load_balancer) {
  // create channels
-  std::string const addresses =
-      etcd::detail::strip_and_resolve_addresses(address);
  grpc::ChannelArguments grpc_args;
  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
  std::shared_ptr<grpc::ChannelCredentials> creds =
      grpc::InsecureChannelCredentials();
  grpc_args.SetLoadBalancingPolicyName(load_balancer);
-  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  this->channel = etcd::detail::create_grpc_channel(address, creds, grpc_args);
  this->token_authenticator.reset(new TokenAuthenticator());

  // create stubs
  stubs.reset(new EtcdServerStubs{});
  stubs->kvServiceStub = KV::NewStub(this->channel);
  stubs->watchServiceStub = Watch::NewStub(this->channel);
+  stubs->clusterServiceStub = Cluster::NewStub(this->channel);
  stubs->leaseServiceStub = Lease::NewStub(this->channel);
  stubs->lockServiceStub = Lock::NewStub(this->channel);
  stubs->electionServiceStub = Election::NewStub(this->channel);
@ -291,14 +402,12 @@ etcd::SyncClient::SyncClient(std::string const& address,
 etcd::SyncClient::SyncClient(std::string const& address,
                             grpc::ChannelArguments const& arguments) {
  // create channels
-  std::string const addresses =
-      etcd::detail::strip_and_resolve_addresses(address);
  grpc::ChannelArguments grpc_args = arguments;
  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
  std::shared_ptr<grpc::ChannelCredentials> creds =
      grpc::InsecureChannelCredentials();
-  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  this->channel = etcd::detail::create_grpc_channel(address, creds, grpc_args);
  this->token_authenticator.reset(new TokenAuthenticator());

  // create stubs
@ -326,15 +435,13 @@ etcd::SyncClient::SyncClient(std::string const& address,
                             int const auth_token_ttl,
                             std::string const& load_balancer) {
  // create channels
-  std::string const addresses =
-      etcd::detail::strip_and_resolve_addresses(address);
  grpc::ChannelArguments grpc_args;
  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
  std::shared_ptr<grpc::ChannelCredentials> creds =
      grpc::InsecureChannelCredentials();
  grpc_args.SetLoadBalancingPolicyName(load_balancer);
-  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  this->channel = etcd::detail::create_grpc_channel(address, creds, grpc_args);

  // auth
  this->token_authenticator.reset(new TokenAuthenticator(
@ -355,14 +462,12 @@ etcd::SyncClient::SyncClient(std::string const& address,
                             int const auth_token_ttl,
                             grpc::ChannelArguments const& arguments) {
  // create channels
-  std::string const addresses =
-      etcd::detail::strip_and_resolve_addresses(address);
  grpc::ChannelArguments grpc_args = arguments;
  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
  std::shared_ptr<grpc::ChannelCredentials> creds =
      grpc::InsecureChannelCredentials();
-  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  this->channel = etcd::detail::create_grpc_channel(address, creds, grpc_args);

  // auth
  this->token_authenticator.reset(new TokenAuthenticator(
@ -400,8 +505,6 @@ etcd::SyncClient::SyncClient(std::string const& address, std::string const& ca,
                             std::string const& target_name_override,
                             std::string const& load_balancer) {
  // create channels
-  std::string const addresses =
-      etcd::detail::strip_and_resolve_addresses(address);
  grpc::ChannelArguments grpc_args;
  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
@ -412,7 +515,7 @@ etcd::SyncClient::SyncClient(std::string const& address, std::string const& ca,
    grpc_args.SetString(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG,
                        target_name_override);
  }
-  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  this->channel = etcd::detail::create_grpc_channel(address, creds, grpc_args);
  this->token_authenticator.reset(new TokenAuthenticator());

  // setup stubs
@ -430,8 +533,6 @@ etcd::SyncClient::SyncClient(std::string const& address, std::string const& ca,
                             std::string const& target_name_override,
                             grpc::ChannelArguments const& arguments) {
  // create channels
-  std::string const addresses =
-      etcd::detail::strip_and_resolve_addresses(address);
  grpc::ChannelArguments grpc_args = arguments;
  grpc_args.SetMaxSendMessageSize(std::numeric_limits<int>::max());
  grpc_args.SetMaxReceiveMessageSize(std::numeric_limits<int>::max());
@ -441,7 +542,7 @@ etcd::SyncClient::SyncClient(std::string const& address, std::string const& ca,
    grpc_args.SetString(GRPC_SSL_TARGET_NAME_OVERRIDE_ARG,
                        target_name_override);
  }
-  this->channel = grpc::CreateCustomChannel(addresses, creds, grpc_args);
+  this->channel = etcd::detail::create_grpc_channel(address, creds, grpc_args);
  this->token_authenticator.reset(new TokenAuthenticator());

  // setup stubs
@ -474,18 +575,6 @@ etcd::SyncClient::~SyncClient() {
  channel.reset();
 }

-/**
- * Note [lease with TTL and issue the actual request]
- *
- * We sometime use the request like `set(key, value, TTL)`, we explain the TTL
- * as the time between the user call the `set()` method between the request is
- * actually executed in etcd server. Thus, we issue a lease request with that
- * TTL value immediately, and pass it to the `set_internal()` method, the later
- * may be issues asynchronously.
- *
- * Thus the TTL could keep the expected semantic even in the async runtime.
- */
-
 etcd::Response etcd::SyncClient::head() {
  return Response::create(this->head_internal());
 }
@ -502,7 +591,8 @@ etcd::Response etcd::SyncClient::get(std::string const& key) {
  return Response::create(this->get_internal(key));
 }

-etcd::Response etcd::SyncClient::get(std::string const& key, int64_t revision) {
+etcd::Response etcd::SyncClient::get(std::string const& key,
+                                     const int64_t revision) {
  return Response::create(this->get_internal(key, revision));
 }

@ -518,62 +608,20 @@ std::shared_ptr<etcdv3::AsyncRangeAction> etcd::SyncClient::get_internal(
  return std::make_shared<etcdv3::AsyncRangeAction>(std::move(params));
 }

-etcd::Response etcd::SyncClient::set(std::string const& key,
-                                     std::string const& value, int ttl) {
-  // See Note [lease with TTL and issue the actual request]
-  int64_t leaseId = 0;
-  if (ttl > 0) {
-    auto res = this->leasegrant(ttl);
-    if (!res.is_ok()) {
-      return etcd::Response(res.error_code(), res.error_message());
-    } else {
-      leaseId = res.value().lease();
-    }
-  }
-  return Response::create(this->set_internal(key, value, leaseId));
-}
-
 etcd::Response etcd::SyncClient::set(std::string const& key,
                                     std::string const& value,
-                                     int64_t leaseid) {
-  return Response::create(this->set_internal(key, value, leaseid));
-}
-
-std::shared_ptr<etcdv3::AsyncSetAction> etcd::SyncClient::set_internal(
-    std::string const& key, std::string const& value, int64_t leaseid) {
-  etcdv3::ActionParameters params;
-  params.key.assign(key);
-  params.value.assign(value);
-  params.lease_id = leaseid;
-  params.auth_token.assign(this->token_authenticator->renew_if_expired());
-  params.grpc_timeout = this->grpc_timeout;
-  params.kv_stub = stubs->kvServiceStub.get();
-  return std::make_shared<etcdv3::AsyncSetAction>(std::move(params), false);
-}
-
-etcd::Response etcd::SyncClient::add(std::string const& key,
-                                     std::string const& value, int ttl) {
-  // See Note [lease with TTL and issue the actual request]
-  int64_t leaseId = 0;
-  if (ttl > 0) {
-    auto res = this->leasegrant(ttl);
-    if (!res.is_ok()) {
-      return etcd::Response(res.error_code(), res.error_message());
-    } else {
-      leaseId = res.value().lease();
-    }
-  }
-  return Response::create(this->add_internal(key, value, leaseId));
+                                     const int64_t leaseid) {
+  return Response::create(this->put_internal(key, value, leaseid));
 }

 etcd::Response etcd::SyncClient::add(std::string const& key,
                                     std::string const& value,
-                                     int64_t leaseid) {
+                                     const int64_t leaseid) {
  return Response::create(this->add_internal(key, value, leaseid));
 }

 std::shared_ptr<etcdv3::AsyncSetAction> etcd::SyncClient::add_internal(
-    std::string const& key, std::string const& value, int64_t leaseid) {
+    std::string const& key, std::string const& value, const int64_t leaseid) {
  etcdv3::ActionParameters params;
  params.key.assign(key);
  params.value.assign(value);
@ -589,40 +637,32 @@ etcd::Response etcd::SyncClient::put(std::string const& key,
  return Response::create(this->put_internal(key, value));
 }

+etcd::Response etcd::SyncClient::put(std::string const& key,
+                                     std::string const& value,
+                                     const int64_t leaseId) {
+  return Response::create(this->put_internal(key, value, leaseId));
+}
+
 std::shared_ptr<etcdv3::AsyncPutAction> etcd::SyncClient::put_internal(
-    std::string const& key, std::string const& value) {
+    std::string const& key, std::string const& value, const int64_t leaseId) {
  etcdv3::ActionParameters params;
  params.key.assign(key);
  params.value.assign(value);
+  params.lease_id = leaseId;
  params.auth_token.assign(this->token_authenticator->renew_if_expired());
  params.grpc_timeout = this->grpc_timeout;
  params.kv_stub = stubs->kvServiceStub.get();
  return std::make_shared<etcdv3::AsyncPutAction>(std::move(params));
 }

-etcd::Response etcd::SyncClient::modify(std::string const& key,
-                                        std::string const& value, int ttl) {
-  // See Note [lease with TTL and issue the actual request]
-  int64_t leaseId = 0;
-  if (ttl > 0) {
-    auto res = leasegrant(ttl);
-    if (!res.is_ok()) {
-      return etcd::Response(res.error_code(), res.error_message());
-    } else {
-      leaseId = res.value().lease();
-    }
-  }
-  return Response::create(this->modify_internal(key, value, leaseId));
-}
-
 etcd::Response etcd::SyncClient::modify(std::string const& key,
                                        std::string const& value,
-                                        int64_t leaseid) {
+                                        const int64_t leaseid) {
  return Response::create(this->modify_internal(key, value, leaseid));
 }

 std::shared_ptr<etcdv3::AsyncUpdateAction> etcd::SyncClient::modify_internal(
-    std::string const& key, std::string const& value, int64_t leaseid) {
+    std::string const& key, std::string const& value, const int64_t leaseid) {
  etcdv3::ActionParameters params;
  params.key.assign(key);
  params.value.assign(value);
@ -636,58 +676,23 @@ std::shared_ptr<etcdv3::AsyncUpdateAction> etcd::SyncClient::modify_internal(
 etcd::Response etcd::SyncClient::modify_if(std::string const& key,
                                           std::string const& value,
                                           std::string const& old_value,
-                                           int ttl) {
-  // See Note [lease with TTL and issue the actual request]
-  int64_t leaseId = 0;
-  if (ttl > 0) {
-    auto res = leasegrant(ttl);
-    if (!res.is_ok()) {
-      return etcd::Response(res.error_code(), res.error_message());
-    } else {
-      leaseId = res.value().lease();
-    }
-  }
+                                           const int64_t leaseid) {
  return Response::create(this->modify_if_internal(
-      key, value, 0, old_value, leaseId, etcdv3::AtomicityType::PREV_VALUE));
-}
-
-etcd::Response etcd::SyncClient::modify_if(std::string const& key,
-                                           std::string const& value,
-                                           std::string const& old_value,
-                                           int64_t leaseid) {
-  return Response::create(this->modify_if_internal(
-      key, value, 0, old_value, leaseid, etcdv3::AtomicityType::PREV_VALUE));
-}
-
-etcd::Response etcd::SyncClient::modify_if(std::string const& key,
-                                           std::string const& value,
-                                           int64_t old_index, int ttl) {
-  // See Note [lease with TTL and issue the actual request]
-  int64_t leaseId = 0;
-  if (ttl > 0) {
-    auto res = leasegrant(ttl);
-    if (!res.is_ok()) {
-      return etcd::Response(res.error_code(), res.error_message());
-    } else {
-      leaseId = res.value().lease();
-    }
-  }
-  return Response::create(this->modify_if_internal(
-      key, value, old_index, "", leaseId, etcdv3::AtomicityType::PREV_INDEX));
+      key, value, 0, old_value, etcdv3::AtomicityType::PREV_VALUE, leaseid));
 }

 etcd::Response etcd::SyncClient::modify_if(std::string const& key,
                                           std::string const& value,
                                           int64_t old_index, int64_t leaseid) {
  return Response::create(this->modify_if_internal(
-      key, value, old_index, "", leaseid, etcdv3::AtomicityType::PREV_INDEX));
+      key, value, old_index, "", etcdv3::AtomicityType::PREV_INDEX, leaseid));
 }

 std::shared_ptr<etcdv3::AsyncCompareAndSwapAction>
 etcd::SyncClient::modify_if_internal(
    std::string const& key, std::string const& value, int64_t old_index,
-    std::string const& old_value, int64_t leaseId,
-    etcdv3::AtomicityType const& atomicity_type) {
+    std::string const& old_value, etcdv3::AtomicityType const& atomicity_type,
+    const int64_t leaseId) {
  etcdv3::ActionParameters params;
  params.key.assign(key);
  params.value.assign(value);
@ -1014,6 +1019,60 @@ etcd::SyncClient::leases_internal() {
  return std::make_shared<etcdv3::AsyncLeaseLeasesAction>(std::move(params));
 }

+etcd::Response etcd::SyncClient::add_member(std::string const& peer_urls,
+                                            bool is_learner) {
+  return Response::create(this->add_member_internal(peer_urls, is_learner));
+}
+
+std::shared_ptr<etcdv3::AsyncAddMemberAction>
+etcd::SyncClient::add_member_internal(std::string const& peer_urls,
+                                      bool is_learner) {
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->token_authenticator->renew_if_expired());
+  params.grpc_timeout = this->grpc_timeout;
+  params.cluster_stub = stubs->clusterServiceStub.get();
+
+  std::vector<std::string> peer_urls_vector;
+  std::istringstream iss(peer_urls);
+  std::string peer_url;
+  while (std::getline(iss, peer_url, ',')) {
+    peer_urls_vector.push_back(peer_url);
+  }
+
+  params.is_learner = is_learner;
+  params.peer_urls = peer_urls_vector;
+
+  return std::make_shared<etcdv3::AsyncAddMemberAction>(std::move(params));
+}
+
+etcd::Response etcd::SyncClient::list_member() {
+  return Response::create(this->list_member_internal());
+}
+
+std::shared_ptr<etcdv3::AsyncListMemberAction>
+etcd::SyncClient::list_member_internal() {
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->token_authenticator->renew_if_expired());
+  params.grpc_timeout = this->grpc_timeout;
+  params.cluster_stub = stubs->clusterServiceStub.get();
+  return std::make_shared<etcdv3::AsyncListMemberAction>(std::move(params));
+}
+
+etcd::Response etcd::SyncClient::remove_member(const uint64_t member_id) {
+  return Response::create(this->remove_member_internal(member_id));
+}
+
+std::shared_ptr<etcdv3::AsyncRemoveMemberAction>
+etcd::SyncClient::remove_member_internal(const uint64_t member_id) {
+  etcdv3::ActionParameters params;
+  params.auth_token.assign(this->token_authenticator->renew_if_expired());
+  params.grpc_timeout = this->grpc_timeout;
+  params.cluster_stub = stubs->clusterServiceStub.get();
+  params.member_id = member_id;
+
+  return std::make_shared<etcdv3::AsyncRemoveMemberAction>(std::move(params));
+}
+
 etcd::Response etcd::SyncClient::lock(std::string const& key) {
  // routines in lock usually will be fast, less than 10 seconds.
  //
@ -1098,15 +1157,15 @@ std::shared_ptr<etcdv3::AsyncUnlockAction> etcd::SyncClient::unlock_internal(
      if (p_keeps_alive != this->keep_alive_for_locks.end()) {
        this->keep_alive_for_locks.erase(p_keeps_alive);
      } else {
-#if !defined(NDEBUG)
-        std::cerr << "Keepalive for lease not found" << std::endl;
+#ifndef NDEBUG
+        std::cerr << "[warn] keepalive for lease not found" << std::endl;
 #endif
      }
      lock_lease_id = p_leases->second;
      this->leases_for_locks.erase(p_leases);
    } else {
-#if !defined(NDEBUG)
-      std::cerr << "Lease for lock not found" << std::endl;
+#ifndef NDEBUG
+      std::cerr << "[warn] lease for lock not found" << std::endl;
 #endif
    }
    if (lock_lease_id != 0) {
--- a/src/Value.cpp
+++ b/src/Value.cpp
@ -1,3 +1,4 @@
+#include <cstdint>
 #include <iomanip>

 #include "etcd/Value.hpp"
@ -44,6 +45,19 @@ int etcd::Value::ttl() const { return _ttl; }

 int64_t etcd::Value::lease() const { return leaseId; }

+std::ostream& etcd::operator<<(std::ostream& os, const etcd::Value& value) {
+  os << "Event: {";
+  os << "Key: " << value.key() << ", ";
+  os << "Value: " << value.as_string() << ", ";
+  os << "Created: " << value.created_index() << ", ";
+  os << "Modified: " << value.modified_index() << ", ";
+  os << "Version: " << value.version() << ", ";
+  os << "TTL: " << value.ttl() << ", ";
+  os << "Lease: " << value.lease() << ", ";
+  os << "}";
+  return os;
+}
+
 etcd::Event::Event(mvccpb::Event const& event) {
  _has_kv = event.has_kv();
  _has_prev_kv = event.has_prev_kv();
@ -73,3 +87,30 @@ bool etcd::Event::has_prev_kv() const { return _has_prev_kv; }
 const etcd::Value& etcd::Event::kv() const { return _kv; }

 const etcd::Value& etcd::Event::prev_kv() const { return _prev_kv; }
+
+std::ostream& etcd::operator<<(std::ostream& os,
+                               const etcd::Event::EventType& value) {
+  switch (value) {
+  case etcd::Event::EventType::PUT:
+    os << "PUT";
+    break;
+  case etcd::Event::EventType::DELETE_:
+    os << "DELETE";
+    break;
+  case etcd::Event::EventType::INVALID:
+    os << "INVALID";
+    break;
+  }
+  return os;
+}
+
+std::ostream& etcd::operator<<(std::ostream& os, const etcd::Event& event) {
+  os << "Event type: " << event.event_type();
+  if (event.has_kv()) {
+    os << ", KV: " << event.kv();
+  }
+  if (event.has_prev_kv()) {
+    os << ", Prev KV: " << event.prev_kv();
+  }
+  return os;
+}
--- a/src/Watcher.cpp
+++ b/src/Watcher.cpp
@ -229,13 +229,18 @@ bool etcd::Watcher::Wait() {
  return stubs->call->Cancelled();
 }

-void etcd::Watcher::Wait(std::function<void(bool)> callback) {
+bool etcd::Watcher::Wait(std::function<void(bool)> callback) {
  if (wait_callback == nullptr) {
    wait_callback = callback;
+    return true;
  } else {
-    std::cerr << "Failed to set a asynchronous wait callback since it has "
+#ifndef NDEBUG
+    std::cerr
+        << "[warn] failed to set a asynchronous wait callback since it has "
           "already been set"
        << std::endl;
+#endif
+    return false;
  }
 }

--- a/src/v3/Action.cpp
+++ b/src/v3/Action.cpp
@ -2,6 +2,15 @@
 #include <grpc/support/log.h>
 #include <grpcpp/support/status.h>
 #include "etcd/v3/action_constants.hpp"
+#include <cstdlib>
+
+#ifndef GPR_ASSERT
+#define GPR_ASSERT(x)                                             \
+  if (!(x)) {                                                     \
+    fprintf(stderr, "%s:%d assert failed\n", __FILE__, __LINE__); \
+    abort();                                                      \
+}
+#endif

 etcdv3::Action::Action(etcdv3::ActionParameters const& params) {
  parameters = params;
--- a/src/v3/AsyncGRPC.cpp
+++ b/src/v3/AsyncGRPC.cpp
@ -43,9 +43,7 @@ void etcdv3::AsyncCampaignResponse::ParseResponse(CampaignResponse& reply) {
  value.kvs.set_lease(leader.lease());
 }

-void etcdv3::AsyncDeleteResponse::ParseResponse(std::string const& key,
-                                                bool prefix,
-                                                DeleteRangeResponse& resp) {
+void etcdv3::AsyncDeleteResponse::ParseResponse(DeleteRangeResponse& resp) {
  index = resp.header().revision();

  if (resp.prev_kvs_size() == 0) {
@ -57,13 +55,15 @@ void etcdv3::AsyncDeleteResponse::ParseResponse(std::string const& key,
      etcdv3::KeyValue kv;
      kv.kvs.CopyFrom(resp.prev_kvs(cnt));
      values.push_back(kv);
+      prev_values.push_back(kv);
    }

-    if (!prefix) {
-      prev_value = values[0];
+    // flatten values/prev_values 0 to value/prev_value
+    if (!values.empty()) {
      value = values[0];
-      value.kvs.clear_value();
-      values.clear();
+    }
+    if (!prev_values.empty()) {
+      prev_value = prev_values[0];
    }
  }
 }
@ -95,6 +95,43 @@ void etcdv3::AsyncLeaseKeepAliveResponse::ParseResponse(
  value.set_ttl(resp.ttl());
 }

+void etcdv3::AsyncMemberAddResponse::ParseResponse(MemberAddResponse& resp) {
+  index = resp.header().revision();
+  std::string member_type = "Member";
+  if (resp.member().islearner()) {
+    member_type = "Learner";
+  }
+  std::cout << "Member (" << resp.member().id() << ")"
+            << " Added to the etcd cluster as " << member_type << std::endl;
+}
+
+void etcdv3::AsyncMemberListResponse::ParseResponse(MemberListResponse& resp) {
+  index = resp.header().revision();
+  for (auto member : resp.members()) {
+    etcdv3::Member m;
+    m.set_id(member.id());
+    m.set_name(member.name());
+
+    std::vector<std::string> clientUrlsVec, peerUrlsVec;
+    for (const auto& clientUrl : member.clienturls()) {
+      clientUrlsVec.push_back(clientUrl);
+    }
+    for (const auto& peerUrl : member.peerurls()) {
+      peerUrlsVec.push_back(peerUrl);
+    }
+
+    m.set_clientURLs(clientUrlsVec);
+    m.set_peerURLs(peerUrlsVec);
+
+    members.push_back(m);
+  }
+}
+
+void etcdv3::AsyncMemberRemoveResponse::ParseResponse(
+    MemberRemoveResponse& resp) {
+  index = resp.header().revision();
+}
+
 void etcdv3::AsyncLeaseLeasesResponse::ParseResponse(
    LeaseLeasesResponse& resp) {
  index = resp.header().revision();
@ -137,6 +174,7 @@ void etcdv3::AsyncPutResponse::ParseResponse(PutResponse& resp) {
  // get all previous values
  etcdv3::KeyValue kv;
  kv.kvs.CopyFrom(resp.prev_kv());
+  prev_values.push_back(kv);
  prev_value = kv;
 }

@ -167,38 +205,99 @@ void etcdv3::AsyncResignResponse::ParseResponse(ResignResponse& reply) {

 void etcdv3::AsyncTxnResponse::ParseResponse(TxnResponse& reply) {
  index = reply.header().revision();
-}
-
-void etcdv3::AsyncTxnResponse::ParseResponse(std::string const& key,
-                                             bool prefix, TxnResponse& reply) {
-  index = reply.header().revision();
  for (int index = 0; index < reply.responses_size(); index++) {
    auto resp = reply.responses(index);
    if (ResponseOp::ResponseCase::kResponseRange == resp.response_case()) {
      AsyncRangeResponse response;
-      response.ParseResponse(*(resp.mutable_response_range()), prefix);
+      response.ParseResponse(*(resp.mutable_response_range()), true);

+      if (error_code == 0) {
        error_code = response.get_error_code();
-      error_message = response.get_error_message();
-
-      values = response.get_values();
-      value = response.get_value();
+      }
+      if (!response.get_error_message().empty()) {
+        if (!error_message.empty()) {
+          error_message += "\n";
+        }
+        error_message += response.get_error_message();
+      }
+      for (auto const& value : response.get_values()) {
+        values.emplace_back(value);
+      }
+      for (auto const& prev_value : response.get_prev_values()) {
+        prev_values.emplace_back(prev_value);
+      }
    } else if (ResponseOp::ResponseCase::kResponsePut == resp.response_case()) {
-      auto put_resp = resp.response_put();
-      if (put_resp.has_prev_kv()) {
-        prev_value.kvs.CopyFrom(put_resp.prev_kv());
+      AsyncPutResponse response;
+      response.ParseResponse(*(resp.mutable_response_put()));
+      if (error_code == 0) {
+        error_code = response.get_error_code();
+      }
+      if (!response.get_error_message().empty()) {
+        if (!error_message.empty()) {
+          error_message += "\n";
+        }
+        error_message += response.get_error_message();
+      }
+      for (auto const& value : response.get_values()) {
+        values.emplace_back(value);
+      }
+      for (auto const& prev_value : response.get_prev_values()) {
+        prev_values.emplace_back(prev_value);
      }
    } else if (ResponseOp::ResponseCase::kResponseDeleteRange ==
               resp.response_case()) {
      AsyncDeleteResponse response;
-      response.ParseResponse(key, prefix,
-                             *(resp.mutable_response_delete_range()));
+      response.ParseResponse(*(resp.mutable_response_delete_range()));

-      prev_value.kvs.CopyFrom(response.get_prev_value().kvs);
-
-      values = response.get_values();
-      value = response.get_value();
+      // Ignore "key not found" error for delete in txn, keep backwards
+      // compatibility.
+      if (response.get_error_code() != 0 &&
+          response.get_error_code() != etcdv3::ERROR_KEY_NOT_FOUND) {
+        error_code = response.get_error_code();
      }
+      if (!response.get_error_message().empty()) {
+        if (response.get_error_code() != 0 &&
+            response.get_error_code() != etcdv3::ERROR_KEY_NOT_FOUND) {
+          if (!error_message.empty()) {
+            error_message += "\n";
+          }
+          error_message += response.get_error_message();
+        }
+      }
+      for (auto const& value : response.get_values()) {
+        values.emplace_back(value);
+      }
+      for (auto const& prev_value : response.get_prev_values()) {
+        prev_values.emplace_back(prev_value);
+      }
+    } else if (ResponseOp::ResponseCase::kResponseTxn == resp.response_case()) {
+      AsyncTxnResponse response;
+      response.ParseResponse(*(resp.mutable_response_txn()));
+
+      if (error_code == 0) {
+        error_code = response.get_error_code();
+      }
+      if (!response.get_error_message().empty()) {
+        if (!error_message.empty()) {
+          error_message += "\n";
+        }
+        error_message += response.get_error_message();
+      }
+
+      // skip
+#ifndef NDEBUG
+      std::cerr << "[debug] not implemented error: unable to parse nested "
+                   "transaction "
+                   "response"
+                << std::endl;
+#endif
+    }
+  }
+  if (!values.empty()) {
+    value = values[0];
+  }
+  if (!prev_values.empty()) {
+    prev_value = prev_values[0];
  }
 }

@ -270,20 +369,17 @@ etcdv3::AsyncCampaignResponse etcdv3::AsyncCampaignAction::ParseResponse() {
 etcdv3::AsyncCompareAndDeleteAction::AsyncCompareAndDeleteAction(
    etcdv3::ActionParameters&& params, etcdv3::AtomicityType type)
    : etcdv3::Action(std::move(params)) {
-  etcdv3::Transaction transaction(parameters.key);
+  etcdv3::Transaction txn;
  if (type == etcdv3::AtomicityType::PREV_VALUE) {
-    transaction.init_compare(parameters.old_value, CompareResult::EQUAL,
-                             CompareTarget::VALUE);
+    txn.setup_compare_and_delete(parameters.key, parameters.old_value,
+                                 parameters.key);
  } else if (type == etcdv3::AtomicityType::PREV_INDEX) {
-    transaction.init_compare(parameters.old_revision, CompareResult::EQUAL,
-                             CompareTarget::MOD);
+    txn.setup_compare_and_delete(parameters.key, parameters.old_revision,
+                                 parameters.key);
  }

-  transaction.setup_compare_and_delete_operation(parameters.key);
-  transaction.setup_basic_failure_operation(parameters.key);
-
  response_reader =
-      parameters.kv_stub->AsyncTxn(&context, *transaction.txn_request, &cq_);
+      parameters.kv_stub->AsyncTxn(&context, *txn.txn_request, &cq_);
  response_reader->Finish(&reply, &status, (void*) this);
 }

@ -295,35 +391,32 @@ etcdv3::AsyncTxnResponse etcdv3::AsyncCompareAndDeleteAction::ParseResponse() {
    txn_resp.set_error_code(status.error_code());
    txn_resp.set_error_message(status.error_message());
  } else {
-    txn_resp.ParseResponse(parameters.key, parameters.withPrefix, reply);
+    txn_resp.ParseResponse(reply);

    if (!reply.succeeded()) {
      txn_resp.set_error_code(ERROR_COMPARE_FAILED);
      txn_resp.set_error_message("etcd-cpp-apiv3: compare failed");
    }
  }
-
  return txn_resp;
 }

 etcdv3::AsyncCompareAndSwapAction::AsyncCompareAndSwapAction(
    etcdv3::ActionParameters&& params, etcdv3::AtomicityType type)
    : etcdv3::Action(std::move(params)) {
-  etcdv3::Transaction transaction(parameters.key);
+  etcdv3::Transaction txn;
  if (type == etcdv3::AtomicityType::PREV_VALUE) {
-    transaction.init_compare(parameters.old_value, CompareResult::EQUAL,
-                             CompareTarget::VALUE);
+    txn.setup_compare_and_swap(parameters.key, parameters.old_value,
+                               parameters.value, parameters.lease_id);
  } else if (type == etcdv3::AtomicityType::PREV_INDEX) {
-    transaction.init_compare(parameters.old_revision, CompareResult::EQUAL,
-                             CompareTarget::MOD);
+    txn.setup_compare_and_swap(parameters.key, parameters.old_revision,
+                               parameters.value, parameters.lease_id);
  }
-
-  transaction.setup_basic_failure_operation(parameters.key);
-  transaction.setup_compare_and_swap_sequence(parameters.value,
-                                              parameters.lease_id);
+  // backwards compatibility
+  txn.add_success_range(parameters.key);

  response_reader =
-      parameters.kv_stub->AsyncTxn(&context, *transaction.txn_request, &cq_);
+      parameters.kv_stub->AsyncTxn(&context, *txn.txn_request, &cq_);
  response_reader->Finish(&reply, &status, (void*) this);
 }

@ -335,7 +428,7 @@ etcdv3::AsyncTxnResponse etcdv3::AsyncCompareAndSwapAction::ParseResponse() {
    txn_resp.set_error_code(status.error_code());
    txn_resp.set_error_message(status.error_message());
  } else {
-    txn_resp.ParseResponse(parameters.key, parameters.withPrefix, reply);
+    txn_resp.ParseResponse(reply);

    // if there is an error code returned by parseResponse, we must
    // not overwrite it.
@ -344,30 +437,15 @@ etcdv3::AsyncTxnResponse etcdv3::AsyncCompareAndSwapAction::ParseResponse() {
      txn_resp.set_error_message("etcd-cpp-apiv3: compare failed");
    }
  }
-
  return txn_resp;
 }

 etcdv3::AsyncDeleteAction::AsyncDeleteAction(ActionParameters&& params)
    : etcdv3::Action(std::move(params)) {
  DeleteRangeRequest del_request;
-  if (!parameters.withPrefix) {
-    del_request.set_key(parameters.key);
-  } else {
-    if (parameters.key.empty()) {
-      // see: WithFromKey in etcdv3/client
-      del_request.set_key(etcdv3::NUL);
-      del_request.set_range_end(etcdv3::NUL);
-    } else {
-      del_request.set_key(parameters.key);
-      del_request.set_range_end(detail::string_plus_one(parameters.key));
-    }
-  }
-  if (!parameters.range_end.empty()) {
-    del_request.set_range_end(parameters.range_end);
-  }
-
-  del_request.set_prev_kv(true);
+  detail::make_request_with_ranges(del_request, parameters.key,
+                                   parameters.range_end, parameters.withPrefix);
+  del_request.set_prev_kv(true /* fetch prev values */);

  response_reader =
      parameters.kv_stub->AsyncDeleteRange(&context, del_request, &cq_);
@ -382,11 +460,8 @@ etcdv3::AsyncDeleteResponse etcdv3::AsyncDeleteAction::ParseResponse() {
    del_resp.set_error_code(status.error_code());
    del_resp.set_error_message(status.error_message());
  } else {
-    del_resp.ParseResponse(
-        parameters.key, parameters.withPrefix || !parameters.range_end.empty(),
-        reply);
+    del_resp.ParseResponse(reply);
  }
-
  return del_resp;
 }

@ -474,7 +549,10 @@ etcdv3::AsyncLeaseKeepAliveAction::AsyncLeaseKeepAliveAction(
      got_tag == (void*) etcdv3::KEEPALIVE_CREATE) {
    // ok
  } else {
-    throw std::runtime_error("Failed to create a lease keep-alive connection");
+    status = grpc::Status(grpc::StatusCode::CANCELLED,
+                          "Failed to create a lease keep-alive connection");
+    // cannot continue for further refresh
+    isCancelled.store(true);
  }
 }

@ -496,7 +574,7 @@ etcd::Response etcdv3::AsyncLeaseKeepAliveAction::Refresh() {
  std::lock_guard<std::recursive_mutex> scope_lock(this->protect_is_cancelled);

  auto start_timepoint = std::chrono::high_resolution_clock::now();
-  if (isCancelled) {
+  if (isCancelled.load()) {
    status = grpc::Status::CANCELLED;
    return etcd::Response(ParseResponse(),
                          etcd::detail::duration_till_now(start_timepoint));
@ -583,9 +661,7 @@ etcd::Response etcdv3::AsyncLeaseKeepAliveAction::Refresh() {

 void etcdv3::AsyncLeaseKeepAliveAction::CancelKeepAlive() {
  std::lock_guard<std::recursive_mutex> scope_lock(this->protect_is_cancelled);
-  if (isCancelled == false) {
-    isCancelled = true;
-
+  if (!isCancelled.exchange(true)) {
    void* got_tag = nullptr;
    bool ok = false;

@ -594,17 +670,22 @@ void etcdv3::AsyncLeaseKeepAliveAction::CancelKeepAlive() {
        got_tag == (void*) etcdv3::KEEPALIVE_DONE) {
      // ok
    } else {
-      std::cerr << "Failed to mark a lease keep-alive connection as DONE: "
+#ifndef NDEBUG
+      std::cerr
+          << "[debug] failed to mark a lease keep-alive connection as DONE: "
          << context.debug_error_string() << std::endl;
+#endif
    }

    stream->Finish(&status, (void*) KEEPALIVE_FINISH);
    if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void*) KEEPALIVE_FINISH) {
      // ok
    } else {
-      std::cerr << "Failed to finish a lease keep-alive connection: "
+#ifndef NDEBUG
+      std::cerr << "[debug] failed to finish a lease keep-alive connection: "
                << status.error_message() << ", "
                << context.debug_error_string() << std::endl;
+#endif
    }

    // cancel on-the-fly calls
@ -615,7 +696,7 @@ void etcdv3::AsyncLeaseKeepAliveAction::CancelKeepAlive() {
 }

 bool etcdv3::AsyncLeaseKeepAliveAction::Cancelled() const {
-  return isCancelled;
+  return isCancelled.load();
 }

 etcdv3::ActionParameters&
@ -623,6 +704,81 @@ etcdv3::AsyncLeaseKeepAliveAction::mutable_parameters() {
  return this->parameters;
 }

+etcdv3::AsyncAddMemberAction::AsyncAddMemberAction(
+    etcdv3::ActionParameters&& params)
+    : etcdv3::Action(std::move(params)) {
+  MemberAddRequest add_member_request;
+
+  for (const auto& url : parameters.peer_urls) {
+    add_member_request.add_peerurls(url);
+  }
+  add_member_request.set_islearner(parameters.is_learner);
+  response_reader = parameters.cluster_stub->AsyncMemberAdd(
+      &context, add_member_request, &cq_);
+  response_reader->Finish(&reply, &status, (void*) this);
+}
+
+etcdv3::AsyncMemberAddResponse etcdv3::AsyncAddMemberAction::ParseResponse() {
+  AsyncMemberAddResponse add_member_resp;
+  add_member_resp.set_action(etcdv3::ADDMEMBER);
+
+  if (!status.ok()) {
+    add_member_resp.set_error_code(status.error_code());
+    add_member_resp.set_error_message(status.error_message());
+  } else {
+    add_member_resp.ParseResponse(reply);
+  }
+  return add_member_resp;
+}
+
+etcdv3::AsyncListMemberAction::AsyncListMemberAction(
+    etcdv3::ActionParameters&& params)
+    : etcdv3::Action(std::move(params)) {
+  MemberListRequest member_list_request;
+
+  response_reader = parameters.cluster_stub->AsyncMemberList(
+      &context, member_list_request, &cq_);
+  response_reader->Finish(&reply, &status, (void*) this);
+}
+
+etcdv3::AsyncMemberListResponse etcdv3::AsyncListMemberAction::ParseResponse() {
+  AsyncMemberListResponse list_member_resp;
+  list_member_resp.set_action(etcdv3::LISTMEMBER);
+
+  if (!status.ok()) {
+    list_member_resp.set_error_code(status.error_code());
+    list_member_resp.set_error_message(status.error_message());
+  } else {
+    list_member_resp.ParseResponse(reply);
+  }
+  return list_member_resp;
+}
+
+etcdv3::AsyncRemoveMemberAction::AsyncRemoveMemberAction(
+    etcdv3::ActionParameters&& params)
+    : etcdv3::Action(std::move(params)) {
+  MemberRemoveRequest remove_member_request;
+
+  remove_member_request.set_id(parameters.member_id);
+  response_reader = parameters.cluster_stub->AsyncMemberRemove(
+      &context, remove_member_request, &cq_);
+  response_reader->Finish(&reply, &status, (void*) this);
+}
+
+etcdv3::AsyncMemberRemoveResponse
+etcdv3::AsyncRemoveMemberAction::ParseResponse() {
+  AsyncMemberRemoveResponse remove_member_resp;
+  remove_member_resp.set_action(etcdv3::REMOVEMEMBER);
+
+  if (!status.ok()) {
+    remove_member_resp.set_error_code(status.error_code());
+    remove_member_resp.set_error_message(status.error_message());
+  } else {
+    remove_member_resp.ParseResponse(reply);
+  }
+  return remove_member_resp;
+}
+
 etcdv3::AsyncLeaseLeasesAction::AsyncLeaseLeasesAction(
    etcdv3::ActionParameters&& params)
    : etcdv3::Action(std::move(params)) {
@ -739,7 +895,10 @@ etcdv3::AsyncObserveAction::AsyncObserveAction(
      got_tag == (void*) etcdv3::ELECTION_OBSERVE_CREATE) {
    // n.b.: leave the issue of `Read` to the `waitForResponse`
  } else {
-    throw std::runtime_error("failed to create a observe connection");
+    status = grpc::Status(grpc::StatusCode::CANCELLED,
+                          "failed to create a observe connection");
+    // cannot continue for further observing
+    isCancelled.store(true);
  }
 }

@ -767,7 +926,7 @@ void etcdv3::AsyncObserveAction::waitForResponse() {
 }

 void etcdv3::AsyncObserveAction::CancelObserve() {
-  std::lock_guard<std::mutex> scope_lock(this->protect_is_cancalled);
+  std::lock_guard<std::mutex> scope_lock(this->protect_is_cancelled);
  if (!isCancelled.exchange(true)) {
    void* got_tag;
    bool ok = false;
@ -785,8 +944,10 @@ void etcdv3::AsyncObserveAction::CancelObserve() {
      break;
    case CompletionQueue::NextStatus::GOT_EVENT:
      if (!ok || got_tag != (void*) ELECTION_OBSERVE_FINISH) {
-        std::cerr << "Failed to finish a election observing connection"
+#ifndef NDEBUG
+        std::cerr << "[debug] failed to finish a election observing connection"
                  << std::endl;
+#endif
      }
    }

@ -874,21 +1035,8 @@ etcdv3::AsyncPutResponse etcdv3::AsyncPutAction::ParseResponse() {
 etcdv3::AsyncRangeAction::AsyncRangeAction(etcdv3::ActionParameters&& params)
    : etcdv3::Action(std::move(params)) {
  RangeRequest get_request;
-  if (!parameters.withPrefix) {
-    get_request.set_key(parameters.key);
-  } else {
-    if (parameters.key.empty()) {
-      // see: WithFromKey in etcdv3/client
-      get_request.set_key(etcdv3::NUL);
-      get_request.set_range_end(etcdv3::NUL);
-    } else {
-      get_request.set_key(parameters.key);
-      get_request.set_range_end(detail::string_plus_one(parameters.key));
-    }
-  }
-  if (!parameters.range_end.empty()) {
-    get_request.set_range_end(parameters.range_end);
-  }
+  detail::make_request_with_ranges(get_request, parameters.key,
+                                   parameters.range_end, parameters.withPrefix);
  if (parameters.revision > 0) {
    get_request.set_revision(parameters.revision);
  }
@ -951,21 +1099,19 @@ etcdv3::AsyncResignResponse etcdv3::AsyncResignAction::ParseResponse() {
 etcdv3::AsyncSetAction::AsyncSetAction(etcdv3::ActionParameters&& params,
                                       bool create)
    : etcdv3::Action(std::move(params)) {
-  etcdv3::Transaction transaction(parameters.key);
+  etcdv3::Transaction txn;
  isCreate = create;
-  transaction.init_compare(CompareResult::EQUAL, CompareTarget::VERSION);
-
-  transaction.setup_basic_create_sequence(parameters.key, parameters.value,
-                                          parameters.lease_id);
-
-  if (isCreate) {
-    transaction.setup_basic_failure_operation(parameters.key);
+  txn.add_compare_mod(parameters.key, 0 /* not exists */);
+  txn.add_success_put(parameters.key, parameters.value, parameters.lease_id);
+  // backwards compatibility
+  txn.add_success_range(parameters.key);
+  if (create) {
+    txn.add_failure_range(parameters.key);
  } else {
-    transaction.setup_set_failure_operation(parameters.key, parameters.value,
-                                            parameters.lease_id);
+    txn.add_failure_put(parameters.key, parameters.value, parameters.lease_id);
  }
  response_reader =
-      parameters.kv_stub->AsyncTxn(&context, *transaction.txn_request, &cq_);
+      parameters.kv_stub->AsyncTxn(&context, *txn.txn_request, &cq_);
  response_reader->Finish(&reply, &status, (void*) this);
 }

@ -977,7 +1123,7 @@ etcdv3::AsyncTxnResponse etcdv3::AsyncSetAction::ParseResponse() {
    txn_resp.set_error_code(status.error_code());
    txn_resp.set_error_message(status.error_message());
  } else {
-    txn_resp.ParseResponse(parameters.key, parameters.withPrefix, reply);
+    txn_resp.ParseResponse(reply);

    if (!reply.succeeded() && isCreate) {
      txn_resp.set_error_code(etcdv3::ERROR_KEY_ALREADY_EXISTS);
@ -1003,7 +1149,7 @@ etcdv3::AsyncTxnResponse etcdv3::AsyncTxnAction::ParseResponse() {
    txn_resp.set_error_code(status.error_code());
    txn_resp.set_error_message(status.error_message());
  } else {
-    txn_resp.ParseResponse(parameters.key, parameters.withPrefix, reply);
+    txn_resp.ParseResponse(reply);

    // if there is an error code returned by parseResponse, we must
    // not overwrite it.
@ -1042,14 +1188,15 @@ etcdv3::AsyncUnlockResponse etcdv3::AsyncUnlockAction::ParseResponse() {

 etcdv3::AsyncUpdateAction::AsyncUpdateAction(etcdv3::ActionParameters&& params)
    : etcdv3::Action(std::move(params)) {
-  etcdv3::Transaction transaction(parameters.key);
-  transaction.init_compare(CompareResult::GREATER, CompareTarget::VERSION);
-
-  transaction.setup_compare_and_swap_sequence(parameters.value,
-                                              parameters.lease_id);
-
+  etcdv3::Transaction txn;
+  txn.add_compare_version(parameters.key, CompareResult::GREATER, 0);  // exists
+  txn.add_success_put(parameters.key, parameters.value, parameters.lease_id,
+                      true /* for backwards compatibility */);
+  // backwards compatibility
+  txn.add_success_range(parameters.key);
+  txn.add_failure_range(parameters.key);
  response_reader =
-      parameters.kv_stub->AsyncTxn(&context, *transaction.txn_request, &cq_);
+      parameters.kv_stub->AsyncTxn(&context, *txn.txn_request, &cq_);
  response_reader->Finish(&reply, &status, (void*) this);
 }

@ -1061,7 +1208,7 @@ etcdv3::AsyncTxnResponse etcdv3::AsyncUpdateAction::ParseResponse() {
    txn_resp.set_error_message(status.error_message());
  } else {
    if (reply.succeeded()) {
-      txn_resp.ParseResponse(parameters.key, parameters.withPrefix, reply);
+      txn_resp.ParseResponse(reply);
      txn_resp.set_action(etcdv3::UPDATE_ACTION);
    } else {
      txn_resp.set_error_code(etcdv3::ERROR_KEY_NOT_FOUND);
@ -1078,28 +1225,14 @@ etcdv3::AsyncWatchAction::AsyncWatchAction(etcdv3::ActionParameters&& params)
                                             (void*) etcdv3::WATCH_CREATE);
  this->watch_id =
      std::chrono::high_resolution_clock::now().time_since_epoch().count();
-// #ifndef NDEBUG
-//   std::clog << "etcd-cpp-apiv3: watch_id: " << this->watch_id << std::endl;
-// #endif
+  // #ifndef NDEBUG
+  //   std::clog << "etcd-cpp-apiv3: watch_id: " << this->watch_id << std::endl;
+  // #endif

  WatchRequest watch_req;
  WatchCreateRequest watch_create_req;
-
-  if (!parameters.withPrefix) {
-    watch_create_req.set_key(parameters.key);
-  } else {
-    if (parameters.key.empty()) {
-      watch_create_req.set_key(etcdv3::NUL);
-      watch_create_req.set_range_end(etcdv3::NUL);
-    } else {
-      watch_create_req.set_key(parameters.key);
-      watch_create_req.set_range_end(detail::string_plus_one(parameters.key));
-    }
-  }
-  if (!parameters.range_end.empty()) {
-    watch_create_req.set_range_end(parameters.range_end);
-  }
-
+  detail::make_request_with_ranges(watch_create_req, parameters.key,
+                                   parameters.range_end, parameters.withPrefix);
  watch_create_req.set_prev_kv(true);
  watch_create_req.set_start_revision(parameters.revision);
  watch_create_req.set_watch_id(this->watch_id);
@ -1113,7 +1246,14 @@ etcdv3::AsyncWatchAction::AsyncWatchAction(etcdv3::ActionParameters&& params)
      got_tag == (void*) etcdv3::WATCH_CREATE) {
    stream->Write(watch_req, (void*) etcdv3::WATCH_WRITE);
  } else {
-    throw std::runtime_error("failed to create a watch connection");
+    status = grpc::Status(grpc::StatusCode::CANCELLED,
+                          "failed to create a watch connection");
+    // cannot continue for further watching
+    isCancelled.store(true);
+  }
+
+  if (!status.ok()) {
+    return;
  }

  // wait "write" (WatchCreateRequest) success, and start to read the first
@ -1121,15 +1261,66 @@ etcdv3::AsyncWatchAction::AsyncWatchAction(etcdv3::ActionParameters&& params)
  if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void*) etcdv3::WATCH_WRITE) {
    stream->Read(&reply, (void*) this);
  } else {
-    throw std::runtime_error("failed to write WatchCreateRequest to server");
+    status = grpc::Status(grpc::StatusCode::CANCELLED,
+                          "failed to write WatchCreateRequest to server");
+    // cannot continue for further watching
+    isCancelled.store(true);
  }
 }

+/**
+ * Notes: `Cancel` and `waitForResponse` of watchers.
+ *
+ * We meet failures about failed to cancel the watcher on Ubuntu 20.04
+ * due to unable to receive the "etcdv3::WATCH_FINISH" tag from the gRPC
+ * completion queue.
+ *
+ * See CI:
+ * https://github.com/etcd-cpp-apiv3/etcd-cpp-apiv3/actions/runs/5561458372/jobs/10159155857
+ *
+ * To address the problem, we use the `AsyncNext()` to wait for the
+ * the last token from the completion queue (wait for 1 second, once
+ * we called the method `stream->Finish()`).
+ *
+ * Remark: the issue might be caused by lower version etcd.
+ */
+
 void etcdv3::AsyncWatchAction::waitForResponse() {
  void* got_tag;
  bool ok = false;
+  bool the_final_round = false;

-  while (cq_.Next(&got_tag, &ok)) {
+  // failed to create the watcher
+  if (!status.ok()) {
+    return;
+  }
+
+  while (true) {
+    if (!the_final_round) {
+      if (!cq_.Next(&got_tag, &ok)) {
+        break;
+      }
+    } else {
+      auto deadline =
+          std::chrono::system_clock::now() + std::chrono::seconds(1);
+      switch (cq_.AsyncNext(&got_tag, &ok, deadline)) {
+      case CompletionQueue::NextStatus::TIMEOUT:
+      case CompletionQueue::NextStatus::SHUTDOWN: {
+#ifndef NDEBUG
+        std::cerr << "[warn] watcher does't exit normally" << std::endl;
+#endif
+        // pretend to be received a "WATCH_FINISH" tag: shutdown
+        context.TryCancel();
+        cq_.Shutdown();
+        ok = false;  // jump out
+        break;
+      }
+      case CompletionQueue::NextStatus::GOT_EVENT: {
+        // normal execution flow
+        break;
+      }
+      }
+    }
    if (ok == false) {
      break;
    }
@ -1138,6 +1329,7 @@ void etcdv3::AsyncWatchAction::waitForResponse() {
      continue;
    }
    if (got_tag == (void*) etcdv3::WATCH_WRITES_DONE) {
+      the_final_round = true;
      stream->Finish(&status, (void*) etcdv3::WATCH_FINISH);
      continue;
    }
@ -1170,7 +1362,6 @@ void etcdv3::AsyncWatchAction::waitForResponse() {
              << std::endl;
        }

-        std::cout << "issue a watch cancel" << std::endl;
        // cancel the watcher after receiving the good response
        this->CancelWatch();

@ -1190,23 +1381,44 @@ void etcdv3::AsyncWatchAction::waitForResponse() {
  }
 }

-void etcdv3::AsyncWatchAction::CancelWatch() {
-  if (!isCancelled.exchange(true)) {
-    WatchRequest cancel_req;
-    cancel_req.mutable_cancel_request()->set_watch_id(this->watch_id);
-    stream->Write(cancel_req, (void*) etcdv3::WATCH_WRITE_CANCEL);
-    isCancelled.store(true);
-  }
-}
-
-bool etcdv3::AsyncWatchAction::Cancelled() const { return isCancelled.load(); }
-
 void etcdv3::AsyncWatchAction::waitForResponse(
    std::function<void(etcd::Response)> callback) {
  void* got_tag;
  bool ok = false;
+  bool the_final_round = false;

-  while (cq_.Next(&got_tag, &ok)) {
+  // failed to create the watcher
+  if (!status.ok()) {
+    auto resp = ParseResponse();
+    auto duration = std::chrono::duration_cast<std::chrono::microseconds>(
+        std::chrono::high_resolution_clock::now() - start_timepoint);
+    callback(etcd::Response(resp, duration));
+  }
+
+  while (true) {
+    if (!the_final_round) {
+      if (!cq_.Next(&got_tag, &ok)) {
+        break;
+      }
+    } else {
+      auto deadline =
+          std::chrono::system_clock::now() + std::chrono::seconds(1);
+      switch (cq_.AsyncNext(&got_tag, &ok, deadline)) {
+      case CompletionQueue::NextStatus::TIMEOUT:
+      case CompletionQueue::NextStatus::SHUTDOWN: {
+        std::cerr << "[warn] watcher does't exit normally" << std::endl;
+        // pretend to be received a "WATCH_FINISH" tag: shutdown
+        context.TryCancel();
+        cq_.Shutdown();
+        ok = false;  // jump out
+        break;
+      }
+      case CompletionQueue::NextStatus::GOT_EVENT: {
+        // normal execution flow
+        break;
+      }
+      }
+    }
    if (ok == false) {
      break;
    }
@ -1215,6 +1427,7 @@ void etcdv3::AsyncWatchAction::waitForResponse(
      continue;
    }
    if (got_tag == (void*) etcdv3::WATCH_WRITES_DONE) {
+      the_final_round = true;
      stream->Finish(&status, (void*) etcdv3::WATCH_FINISH);
      continue;
    }
@ -1257,6 +1470,17 @@ void etcdv3::AsyncWatchAction::waitForResponse(
  }
 }

+void etcdv3::AsyncWatchAction::CancelWatch() {
+  if (!isCancelled.exchange(true)) {
+    WatchRequest cancel_req;
+    cancel_req.mutable_cancel_request()->set_watch_id(this->watch_id);
+    stream->Write(cancel_req, (void*) etcdv3::WATCH_WRITE_CANCEL);
+    isCancelled.store(true);
+  }
+}
+
+bool etcdv3::AsyncWatchAction::Cancelled() const { return isCancelled.load(); }
+
 etcdv3::AsyncWatchResponse etcdv3::AsyncWatchAction::ParseResponse() {
  AsyncWatchResponse watch_resp;
  watch_resp.set_action(etcdv3::WATCH_ACTION);
--- a/src/v3/Member.cpp
+++ b/src/v3/Member.cpp
@ -0,0 +1,40 @@
+#include "etcd/v3/Member.hpp"
+
+etcdv3::Member::Member() {
+  id = 0;
+  name = "";
+  peerURLs = {};
+  clientURLs = {};
+  isLearner = false;
+}
+
+void etcdv3::Member::set_id(uint64_t const& id) { this->id = id; }
+
+void etcdv3::Member::set_name(std::string const& name) { this->name = name; }
+
+void etcdv3::Member::set_peerURLs(std::vector<std::string> const& peerURLs) {
+  this->peerURLs = peerURLs;
+}
+
+void etcdv3::Member::set_clientURLs(
+    std::vector<std::string> const& clientURLs) {
+  this->clientURLs = clientURLs;
+}
+
+void etcdv3::Member::set_learner(bool isLearner) {
+  this->isLearner = isLearner;
+}
+
+uint64_t const& etcdv3::Member::get_id() const { return id; }
+
+std::string const& etcdv3::Member::get_name() const { return name; }
+
+std::vector<std::string> const& etcdv3::Member::get_peerURLs() const {
+  return peerURLs;
+}
+
+std::vector<std::string> const& etcdv3::Member::get_clientURLs() const {
+  return clientURLs;
+}
+
+bool etcdv3::Member::get_learner() const { return isLearner; }
--- a/src/v3/Transaction.cpp
+++ b/src/v3/Transaction.cpp
@ -2,11 +2,7 @@

 #include "proto/rpc.grpc.pb.h"

-using etcdserverpb::Compare;
-using etcdserverpb::DeleteRangeRequest;
-using etcdserverpb::PutRequest;
-using etcdserverpb::RangeRequest;
-using etcdserverpb::RequestOp;
+#include "etcd/v3/Action.hpp"

 namespace etcdv3 {

@ -28,185 +24,337 @@ etcdv3::Transaction::Transaction() {
  txn_request.reset(new etcdserverpb::TxnRequest{});
 }

-etcdv3::Transaction::Transaction(const std::string& key) : key(key) {
-  txn_request.reset(new etcdserverpb::TxnRequest{});
+etcdv3::Transaction::~Transaction() {}
+
+void etcdv3::Transaction::add_compare(std::string const& key,
+                                      CompareTarget const& target,
+                                      CompareResult const& result,
+                                      Value const& target_value,
+                                      std::string const& range_end) {
+  switch (target) {
+  case CompareTarget::VERSION:
+    add_compare_version(key, result, target_value.version, range_end);
+    break;
+  case CompareTarget::CREATE:
+    add_compare_create(key, result, target_value.create_revision, range_end);
+    break;
+  case CompareTarget::MOD:
+    add_compare_mod(key, result, target_value.mod_revision, range_end);
+    break;
+  case CompareTarget::VALUE:
+    add_compare_value(key, result, target_value.value, range_end);
+    break;
+  case CompareTarget::LEASE:
+    add_compare_lease(key, result, target_value.lease, range_end);
+    break;
+  default:
+    // ignore invalid compare target
+    break;
+  }
 }

-void etcdv3::Transaction::reset_key(std::string const& newkey) { key = newkey; }
+void etcdv3::Transaction::add_compare_version(std::string const& key,
+                                              int64_t const& version,
+                                              std::string const& range_end) {
+  this->add_compare_version(key, CompareResult::EQUAL, version, range_end);
+}

-void etcdv3::Transaction::init_compare(CompareResult result,
-                                       CompareTarget target) {
-  Compare* compare = txn_request->add_compare();
+void etcdv3::Transaction::add_compare_version(std::string const& key,
+                                              CompareResult const& result,
+                                              int64_t const& version,
+                                              std::string const& range_end) {
+  auto compare = txn_request->add_compare();
  compare->set_result(detail::to_compare_result(result));
-  compare->set_target(detail::to_compare_target(target));
+  compare->set_target(detail::to_compare_target(CompareTarget::VERSION));
  compare->set_key(key);
-
-  compare->set_version(0);
+  compare->set_version(version);
+  compare->set_range_end(range_end);
 }

-void etcdv3::Transaction::init_compare(std::string const& old_value,
-                                       CompareResult result,
-                                       CompareTarget target) {
-  Compare* compare = txn_request->add_compare();
+void etcdv3::Transaction::add_compare_create(std::string const& key,
+                                             int64_t const& create_revision,
+                                             std::string const& range_end) {
+  this->add_compare_create(key, CompareResult::EQUAL, create_revision,
+                           range_end);
+}
+
+void etcdv3::Transaction::add_compare_create(std::string const& key,
+                                             CompareResult const& result,
+                                             int64_t const& create_revision,
+                                             std::string const& range_end) {
+  auto compare = txn_request->add_compare();
  compare->set_result(detail::to_compare_result(result));
-  compare->set_target(detail::to_compare_target(target));
+  compare->set_target(detail::to_compare_target(CompareTarget::CREATE));
  compare->set_key(key);
-
-  compare->set_value(old_value);
+  compare->set_create_revision(create_revision);
+  compare->set_range_end(range_end);
 }

-void etcdv3::Transaction::init_compare(int64_t old_index, CompareResult result,
-                                       CompareTarget target) {
-  Compare* compare = txn_request->add_compare();
+void etcdv3::Transaction::add_compare_mod(std::string const& key,
+                                          int64_t const& mod_revision,
+                                          std::string const& range_end) {
+  this->add_compare_mod(key, CompareResult::EQUAL, mod_revision, range_end);
+}
+
+void etcdv3::Transaction::add_compare_mod(std::string const& key,
+                                          CompareResult const& result,
+                                          int64_t const& mod_revision,
+                                          std::string const& range_end) {
+  auto compare = txn_request->add_compare();
  compare->set_result(detail::to_compare_result(result));
-  compare->set_target(detail::to_compare_target(target));
+  compare->set_target(detail::to_compare_target(CompareTarget::MOD));
  compare->set_key(key);
-
-  compare->set_mod_revision(old_index);
+  compare->set_mod_revision(mod_revision);
+  compare->set_range_end(range_end);
 }

-/**
- * get key on failure
- */
-void etcdv3::Transaction::setup_basic_failure_operation(
-    std::string const& key) {
-  std::unique_ptr<RangeRequest> get_request(new RangeRequest());
-  get_request->set_key(key);
-  RequestOp* req_failure = txn_request->add_failure();
-  req_failure->set_allocated_request_range(get_request.release());
-}
-
-/**
- * get key on failure, get key before put, modify and then get updated key
- */
-void etcdv3::Transaction::setup_set_failure_operation(std::string const& key,
+void etcdv3::Transaction::add_compare_value(std::string const& key,
                                            std::string const& value,
-                                                      int64_t leaseid) {
-  std::unique_ptr<PutRequest> put_request(new PutRequest());
-  put_request->set_key(key);
-  put_request->set_value(value);
-  put_request->set_prev_kv(true);
-  put_request->set_lease(leaseid);
-  RequestOp* req_failure = txn_request->add_failure();
-  req_failure->set_allocated_request_put(put_request.release());
-
-  std::unique_ptr<RangeRequest> get_request(new RangeRequest());
-  get_request->set_key(key);
-  req_failure = txn_request->add_failure();
-  req_failure->set_allocated_request_range(get_request.release());
+                                            std::string const& range_end) {
+  this->add_compare_value(key, CompareResult::EQUAL, value, range_end);
 }

-/**
- * add key and then get new value of key
- */
-void etcdv3::Transaction::setup_basic_create_sequence(std::string const& key,
+void etcdv3::Transaction::add_compare_value(std::string const& key,
+                                            CompareResult const& result,
                                            std::string const& value,
-                                                      int64_t leaseid) {
-  std::unique_ptr<PutRequest> put_request(new PutRequest());
-  put_request->set_key(key);
-  put_request->set_value(value);
-  put_request->set_prev_kv(true);
-  put_request->set_lease(leaseid);
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_put(put_request.release());
-
-  std::unique_ptr<RangeRequest> get_request(new RangeRequest());
-  get_request->set_key(key);
-  req_success = txn_request->add_success();
-  req_success->set_allocated_request_range(get_request.release());
+                                            std::string const& range_end) {
+  auto compare = txn_request->add_compare();
+  compare->set_result(detail::to_compare_result(result));
+  compare->set_target(detail::to_compare_target(CompareTarget::VALUE));
+  compare->set_key(key);
+  compare->set_value(value);
+  compare->set_range_end(range_end);
 }

-/**
- * get key value then modify and get new value
- */
-void etcdv3::Transaction::setup_compare_and_swap_sequence(
-    std::string const& value, int64_t leaseid) {
-  std::unique_ptr<PutRequest> put_request(new PutRequest());
-  put_request->set_key(key);
-  put_request->set_value(value);
-  put_request->set_prev_kv(true);
-  put_request->set_lease(leaseid);
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_put(put_request.release());
-
-  std::unique_ptr<RangeRequest> get_request(new RangeRequest());
-  get_request->set_key(key);
-  req_success = txn_request->add_success();
-  req_success->set_allocated_request_range(get_request.release());
+void etcdv3::Transaction::add_compare_lease(std::string const& key,
+                                            int64_t const& lease,
+                                            std::string const& range_end) {
+  this->add_compare_lease(key, CompareResult::EQUAL, lease, range_end);
 }

-/**
- * get key, delete
- */
-void etcdv3::Transaction::setup_delete_sequence(std::string const& key,
+void etcdv3::Transaction::add_compare_lease(std::string const& key,
+                                            CompareResult const& result,
+                                            int64_t const& lease,
+                                            std::string const& range_end) {
+  auto compare = txn_request->add_compare();
+  compare->set_result(detail::to_compare_result(result));
+  compare->set_target(detail::to_compare_target(CompareTarget::LEASE));
+  compare->set_key(key);
+  compare->set_lease(lease);
+  compare->set_range_end(range_end);
+}
+
+void etcdv3::Transaction::add_success_range(std::string const& key,
                                            std::string const& range_end,
-                                                bool recursive) {
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
-  del_request->set_key(key);
-  del_request->set_prev_kv(true);
-  if (recursive) {
-    del_request->set_range_end(range_end);
-  }
-
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_delete_range(del_request.release());
+                                            bool const recursive,
+                                            const int64_t limit) {
+  auto succ = txn_request->add_success();
+  auto get_request = succ->mutable_request_range();
+  etcdv3::detail::make_request_with_ranges(*get_request, key, range_end,
+                                           recursive);
+  get_request->set_limit(limit);
 }

-/**
- * get key, delete
- */
-void etcdv3::Transaction::setup_delete_failure_operation(
-    std::string const& key, std::string const& range_end, bool recursive) {
-  std::unique_ptr<RangeRequest> get_request(new RangeRequest());
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
-  get_request.reset(new RangeRequest());
-  get_request->set_key(key);
-  if (recursive) {
-    get_request->set_range_end(range_end);
-    get_request->set_sort_target(
-        RangeRequest::SortTarget::RangeRequest_SortTarget_KEY);
-    get_request->set_sort_order(
-        RangeRequest::SortOrder::RangeRequest_SortOrder_ASCEND);
-  }
-  RequestOp* req_failure = txn_request->add_failure();
-  req_failure->set_allocated_request_range(get_request.release());
-
-  del_request.reset(new DeleteRangeRequest());
-  del_request->set_key(key);
-  if (recursive) {
-    del_request->set_range_end(range_end);
-  }
-
-  req_failure = txn_request->add_failure();
-  req_failure->set_allocated_request_delete_range(del_request.release());
+void etcdv3::Transaction::add_success_put(std::string const& key,
+                                          std::string const& value,
+                                          int64_t const leaseid,
+                                          const bool prev_kv) {
+  auto succ = txn_request->add_success();
+  auto put_request = succ->mutable_request_put();
+  put_request->set_key(key);
+  put_request->set_value(value);
+  put_request->set_prev_kv(prev_kv);
+  put_request->set_lease(leaseid);
 }

-void etcdv3::Transaction::setup_compare_and_delete_operation(
-    std::string const& key) {
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
-  del_request->set_key(key);
-  del_request->set_prev_kv(true);
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_delete_range(del_request.release());
+void etcdv3::Transaction::add_success_delete(std::string const& key,
+                                             std::string const& range_end,
+                                             bool const recursive,
+                                             const bool prev_kv) {
+  auto succ = txn_request->add_success();
+  auto del_request = succ->mutable_request_delete_range();
+  etcdv3::detail::make_request_with_ranges(*del_request, key, range_end,
+                                           recursive);
+  del_request->set_prev_kv(prev_kv);
+}
+
+void etcdv3::Transaction::add_success_txn(
+    const std::shared_ptr<Transaction> txn) {
+  auto succ = txn_request->add_success();
+  auto txn_request = succ->mutable_request_txn();
+  txn_request->CopyFrom(*txn->txn_request);
+}
+
+void etcdv3::Transaction::add_failure_range(std::string const& key,
+                                            std::string const& range_end,
+                                            bool const recursive,
+                                            const int64_t limit) {
+  auto fail = txn_request->add_failure();
+  auto get_request = fail->mutable_request_range();
+  etcdv3::detail::make_request_with_ranges(*get_request, key, range_end,
+                                           recursive);
+  get_request->set_limit(limit);
+}
+
+void etcdv3::Transaction::add_failure_put(std::string const& key,
+                                          std::string const& value,
+                                          int64_t const leaseid,
+                                          const bool prev_kv) {
+  auto fail = txn_request->add_failure();
+  auto put_request = fail->mutable_request_put();
+  put_request->set_key(key);
+  put_request->set_value(value);
+  put_request->set_prev_kv(prev_kv);
+  put_request->set_lease(leaseid);
+}
+
+void etcdv3::Transaction::add_failure_delete(std::string const& key,
+                                             std::string const& range_end,
+                                             bool const recursive,
+                                             const bool prev_kv) {
+  auto fail = txn_request->add_failure();
+  auto del_request = fail->mutable_request_delete_range();
+  etcdv3::detail::make_request_with_ranges(*del_request, key, range_end,
+                                           recursive);
+  del_request->set_prev_kv(prev_kv);
+}
+
+void etcdv3::Transaction::add_failure_txn(
+    const std::shared_ptr<Transaction> txn) {
+  auto fail = txn_request->add_failure();
+  auto txn_request = fail->mutable_request_txn();
+  txn_request->CopyFrom(*txn->txn_request);
+}
+
+void etcdv3::Transaction::setup_compare_and_create(
+    std::string const& key, std::string const& prev_value,
+    std::string const& create_key, std::string const& value,
+    int64_t const leaseid) {
+  this->add_compare_value(key, CompareResult::EQUAL, prev_value);
+  this->add_success_put(create_key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_or_create(std::string const& key,
+                                                  std::string const& prev_value,
+                                                  std::string const& create_key,
+                                                  std::string const& value,
+                                                  int64_t const leaseid) {
+  this->add_compare_value(key, CompareResult::NOT_EQUAL, prev_value);
+  this->add_success_put(create_key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_and_swap(std::string const& key,
+                                                 std::string const& prev_value,
+                                                 std::string const& value,
+                                                 int64_t const leaseid) {
+  this->add_compare_value(key, CompareResult::EQUAL, prev_value);
+  this->add_success_put(key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_or_swap(std::string const& key,
+                                                std::string const& prev_value,
+                                                std::string const& value,
+                                                int64_t const leaseid) {
+  this->add_compare_value(key, CompareResult::NOT_EQUAL, prev_value);
+  this->add_success_put(key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_and_delete(
+    std::string const& key, std::string const& prev_value,
+    std::string const& delete_key, std::string const& range_end,
+    const bool recursive) {
+  this->add_compare_value(key, CompareResult::EQUAL, prev_value);
+  this->add_success_delete(delete_key, range_end, recursive,
+                           true /* for backwards compatibility */);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_or_delete(std::string const& key,
+                                                  std::string const& prev_value,
+                                                  std::string const& delete_key,
+                                                  std::string const& range_end,
+                                                  const bool recursive) {
+  this->add_compare_value(key, CompareResult::NOT_EQUAL, prev_value);
+  this->add_success_delete(delete_key, range_end, recursive,
+                           true /* for backwards compatibility */);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_and_create(
+    std::string const& key, const int64_t prev_revision,
+    std::string const& create_key, std::string const& value,
+    int64_t const leaseid) {
+  this->add_compare_mod(key, CompareResult::EQUAL, prev_revision);
+  this->add_success_put(create_key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_or_create(std::string const& key,
+                                                  const int64_t prev_revision,
+                                                  std::string const& create_key,
+                                                  std::string const& value,
+                                                  int64_t const leaseid) {
+  this->add_compare_mod(key, CompareResult::NOT_EQUAL, prev_revision);
+  this->add_success_put(create_key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_and_swap(std::string const& key,
+                                                 const int64_t prev_revision,
+                                                 std::string const& value,
+                                                 int64_t const leaseid) {
+  this->add_compare_mod(key, CompareResult::EQUAL, prev_revision);
+  this->add_success_put(key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_or_swap(std::string const& key,
+                                                const int64_t prev_revision,
+                                                std::string const& value,
+                                                int64_t const leaseid) {
+  this->add_compare_mod(key, CompareResult::NOT_EQUAL, prev_revision);
+  this->add_success_put(key, value, leaseid);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_and_delete(
+    std::string const& key, const int64_t prev_revision,
+    std::string const& delete_key, std::string const& range_end,
+    const bool recursive) {
+  this->add_compare_mod(key, CompareResult::EQUAL, prev_revision);
+  this->add_success_delete(delete_key, range_end, recursive,
+                           true /* for backwards compatibility */);
+  this->add_failure_range(key);
+}
+
+void etcdv3::Transaction::setup_compare_or_delete(std::string const& key,
+                                                  const int64_t prev_revision,
+                                                  std::string const& delete_key,
+                                                  std::string const& range_end,
+                                                  const bool recursive) {
+  this->add_compare_mod(key, CompareResult::NOT_EQUAL, prev_revision);
+  this->add_success_delete(delete_key, range_end, recursive,
+                           true /* for backwards compatibility */);
+  this->add_failure_range(key);
 }

 void etcdv3::Transaction::setup_put(std::string const& key,
                                    std::string const& value) {
-  std::unique_ptr<PutRequest> put_request(new PutRequest());
-  put_request->set_key(key);
-  put_request->set_value(value);
-  put_request->set_prev_kv(false);
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_put(put_request.release());
+  this->add_success_put(key, value);
 }

 void etcdv3::Transaction::setup_delete(std::string const& key) {
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
-  del_request->set_key(key);
-  del_request->set_prev_kv(false);
-
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_delete_range(del_request.release());
+  this->add_success_delete(key, "", false,
+                           true /* for backwards compatibility */);
 }

-etcdv3::Transaction::~Transaction() {}
+void etcdv3::Transaction::setup_delete(std::string const& key,
+                                       std::string const& range_end,
+                                       const bool recursive) {
+  this->add_success_delete(key, range_end, recursive,
+                           true /* for backwards compatibility */);
+}
--- a/src/v3/V3Response.cpp
+++ b/src/v3/V3Response.cpp
@ -1,4 +1,5 @@
 #include "etcd/v3/V3Response.hpp"
+#include "etcd/v3/Member.hpp"
 #include "etcd/v3/action_constants.hpp"

 void etcdv3::V3Response::set_error_code(int code) { error_code = code; }
@ -79,3 +80,7 @@ uint64_t etcdv3::V3Response::get_raft_term() const { return this->raft_term; }
 std::vector<int64_t> const& etcdv3::V3Response::get_leases() const {
  return this->leases;
 }
+
+std::vector<etcdv3::Member> const& etcdv3::V3Response::get_members() const {
+  return this->members;
+}
--- a/src/v3/action_constants.cpp
+++ b/src/v3/action_constants.cpp
@ -5,7 +5,7 @@ char const* etcdv3::COMPARESWAP_ACTION = "compareAndSwap";
 char const* etcdv3::UPDATE_ACTION = "update";
 char const* etcdv3::SET_ACTION = "set";
 char const* etcdv3::GET_ACTION = "get";
-char const* etcdv3::PUT_ACTION = "put";
+char const* etcdv3::PUT_ACTION = "set";  // alias
 char const* etcdv3::DELETE_ACTION = "delete";
 char const* etcdv3::COMPAREDELETE_ACTION = "compareAndDelete";
 char const* etcdv3::LOCK_ACTION = "lock";
@ -19,6 +19,10 @@ char const* etcdv3::LEASEKEEPALIVE = "leasekeepalive";
 char const* etcdv3::LEASETIMETOLIVE = "leasetimetolive";
 char const* etcdv3::LEASELEASES = "leaseleases";

+char const* etcdv3::ADDMEMBER = "addmember";
+char const* etcdv3::LISTMEMBER = "listmember";
+char const* etcdv3::REMOVEMEMBER = "removemember";
+
 char const* etcdv3::CAMPAIGN_ACTION = "campaign";
 char const* etcdv3::PROCLAIM_ACTION = "preclaim";
 char const* etcdv3::LEADER_ACTION = "leader";
--- a/tst/CMakeLists.txt
+++ b/tst/CMakeLists.txt
@ -19,6 +19,7 @@ foreach(testfile ${TEST_FILES})
        add_executable(${test_name} EXCLUDE_FROM_ALL ${CMAKE_CURRENT_SOURCE_DIR}/${testfile})
    endif()
    use_cxx(${test_name})
+    set_exceptions(${test_name})
    add_test(NAME ${test_name} COMMAND $<TARGET_FILE:${test_name}>)

    target_include_directories(${test_name} PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/../proto/gen)
--- a/tst/EtcdMemberTest.cpp
+++ b/tst/EtcdMemberTest.cpp
@ -0,0 +1,136 @@
+#include <cmath>
+#define CATCH_CONFIG_MAIN
+#include <catch.hpp>
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <chrono>
+#include <cstring>
+#include <iostream>
+#include <thread>
+#include <vector>
+
+#include "etcd/Client.hpp"
+
+static const std::string etcd_url =
+    etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
+
+pid_t new_etcd_pid = 0;
+
+pid_t start_etcd_server(const std::string& etcd_path,
+                        const std::vector<std::string>& args) {
+  pid_t pid = fork();
+  if (pid == -1) {
+    std::cout << "Failed to fork process" << std::endl;
+    exit(EXIT_FAILURE);
+  } else if (pid == 0) {
+    std::vector<char*> c_args;
+    c_args.push_back(const_cast<char*>(etcd_path.c_str()));
+    for (const auto& arg : args) {
+      c_args.push_back(const_cast<char*>(arg.c_str()));
+    }
+    c_args.push_back(nullptr);
+
+    if (execvp(etcd_path.c_str(), c_args.data()) == -1) {
+      std::cout << "Failed to exec etcd process: " << std::strerror(errno)
+                << std::endl;
+      exit(EXIT_FAILURE);
+    }
+  }
+
+  return pid;
+}
+
+TEST_CASE("add member") {
+  etcd::Client etcd(etcd_url);
+  etcd::Response res = etcd.list_member().get();
+  REQUIRE(res.is_ok());
+  CHECK(1 == res.members().size());
+
+  std::string member_name = res.members()[0].get_name();
+  std::string prev_peer_urls = res.members()[0].get_peerURLs()[0];
+
+  // Add a new member
+  std::string peer_urls = "http://127.0.0.1:33691";
+  std::string client_urls = "http://127.0.0.1:33690";
+  bool is_learner = false;
+  res = etcd.add_member(peer_urls, is_learner).get();
+  REQUIRE(res.is_ok());
+
+  // Create the directory for the new etcd server
+  std::string cmd = "mkdir -p /tmp/new_etcd_member";
+  system(cmd.c_str());
+
+  // Start a new etcd server
+  std::vector<std::string> args = {
+      "--name",
+      "new_etcd_member",
+      "--initial-advertise-peer-urls",
+      peer_urls,
+      "--listen-peer-urls",
+      peer_urls,
+      "--initial-cluster",
+      member_name + "=" + prev_peer_urls + ",new_etcd_member=" + peer_urls,
+      "--initial-cluster-state",
+      "existing",
+      "--listen-client-urls",
+      client_urls,
+      "--advertise-client-urls",
+      client_urls,
+      "--data-dir",
+      "/tmp/new_etcd_member",
+  };
+
+  new_etcd_pid = start_etcd_server("/usr/local/bin/etcd", args);
+
+  std::this_thread::sleep_for(std::chrono::seconds(30));
+
+  // Check the member's number
+  {
+    etcd::Response res = etcd.list_member().get();
+    REQUIRE(res.is_ok());
+    CHECK(2 == res.members().size());
+  }
+}
+
+TEST_CASE("member remove") {
+  etcd::Client etcd(etcd_url);
+  etcd::Response res = etcd.list_member().get();
+  REQUIRE(res.is_ok());
+  CHECK(2 == res.members().size());
+
+  uint64_t member_id = 0;
+  for (const auto& member : res.members()) {
+    if (member.get_name() == "new_etcd_member") {
+      member_id = member.get_id();
+      break;
+    }
+  }
+
+  REQUIRE(member_id != 0);
+  // Remove the new member
+  res = etcd.remove_member(member_id).get();
+
+  std::this_thread::sleep_for(std::chrono::seconds(30));
+
+  // Check whether the new etcd server is quited
+  {
+    int status;
+    pid_t wpid = waitpid(new_etcd_pid, &status, WNOHANG);
+    REQUIRE(wpid == new_etcd_pid);
+    REQUIRE(WIFEXITED(status));
+    REQUIRE(WEXITSTATUS(status) == 0);
+  }
+
+  // Remove the directory for the new etcd server
+  std::string cmd = "rm -rf /tmp/new_etcd_member";
+  system(cmd.c_str());
+
+  // Check the member's number
+  {
+    etcd::Response res = etcd.list_member().get();
+    REQUIRE(res.is_ok());
+    CHECK(1 == res.members().size());
+  }
+}
--- a/tst/EtcdResolverTest.cpp
+++ b/tst/EtcdResolverTest.cpp
@ -0,0 +1,30 @@
+#define CATCH_CONFIG_MAIN
+#include <catch.hpp>
+
+#include <iostream>
+
+#include "etcd/Client.hpp"
+
+static const std::string etcd_v4_url =
+    etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
+static const std::string etcd_v6_url =
+    etcdv3::detail::resolve_etcd_endpoints("http://::1:2379");
+// http://[ipv6]:port url
+static const std::string etcd_ipv6_url =
+    etcdv3::detail::resolve_etcd_endpoints("http://[::1]:2379");
+
+TEST_CASE("test ipv4 connection") {
+  std::cout << "ipv4 endpoints: " << etcd_v4_url << std::endl;
+  etcd::Client etcd(etcd_v4_url);
+  REQUIRE(etcd.head().get().is_ok());
+}
+
+TEST_CASE("test ipv6 connection") {
+  std::cout << "ipv6 endpoints: " << etcd_v6_url << std::endl;
+  etcd::Client etcd(etcd_v6_url);
+  REQUIRE(etcd.head().get().is_ok());
+
+  std::cout << "ipv6 endpoints: " << etcd_ipv6_url << std::endl;
+  etcd::Client etcd1(etcd_ipv6_url);
+  REQUIRE(etcd1.head().get().is_ok());
+}
--- a/tst/EtcdSyncTest.cpp
+++ b/tst/EtcdSyncTest.cpp
@ -12,17 +12,22 @@ TEST_CASE("sync operations") {
  etcd::SyncClient etcd(etcd_url);
  etcd.rmdir("/test", true);

+  etcd::Response res;
+  int64_t index;
+
  // add
  CHECK(0 == etcd.add("/test/key1", "42").error_code());
  CHECK(etcd::ERROR_KEY_ALREADY_EXISTS ==
-        etcd.add("/test/key1", "42").error_code());  // Key already exists
+        etcd.add("/test/key1", "41").error_code());  // Key already exists
  CHECK("42" == etcd.get("/test/key1").value().as_string());

  // modify
  CHECK(0 == etcd.modify("/test/key1", "43").error_code());
  CHECK(etcd::ERROR_KEY_NOT_FOUND ==
        etcd.modify("/test/key2", "43").error_code());  // Key not found
-  CHECK("43" == etcd.modify("/test/key1", "42").prev_value().as_string());
+  res = etcd.modify("/test/key1", "42");
+  CHECK(0 == res.error_code());
+  CHECK("43" == res.prev_value().as_string());

  // set
  CHECK(0 == etcd.set("/test/key1", "43").error_code());  // overwrite
@ -60,7 +65,7 @@ TEST_CASE("sync operations") {

  // compare and swap
  etcd.set("/test/key1", "42");
-  int64_t index = etcd.modify_if("/test/key1", "43", "42").index();
+  index = etcd.modify_if("/test/key1", "43", "42").index();
  CHECK(etcd::ERROR_COMPARE_FAILED ==
        etcd.modify_if("/test/key1", "44", "42").error_code());
  REQUIRE(etcd.modify_if("/test/key1", "44", index).is_ok());
@ -71,16 +76,20 @@ TEST_CASE("sync operations") {
  etcd.set("/test/key1", "42");
  CHECK(etcd::ERROR_COMPARE_FAILED ==
        etcd.rm_if("/test/key1", "43").error_code());
-  CHECK(0 == etcd.rm_if("/test/key1", "42").error_code());
+  res = etcd.rm_if("/test/key1", "42");
+  CHECK(
+      (0 == res.error_code() || etcd::ERROR_KEY_NOT_FOUND == res.error_code()));

  // atomic compare-and-delete based on prevIndex
  index = etcd.set("/test/key1", "42").index();
  CHECK(etcd::ERROR_COMPARE_FAILED ==
        etcd.rm_if("/test/key1", index - 1).error_code());
-  CHECK(0 == etcd.rm_if("/test/key1", index).error_code());
+  res = etcd.rm_if("/test/key1", index);
+  CHECK(
+      (0 == res.error_code() || etcd::ERROR_KEY_NOT_FOUND == res.error_code()));

  // leasegrant
-  etcd::Response res = etcd.leasegrant(60);
+  res = etcd.leasegrant(60);
  REQUIRE(res.is_ok());
  CHECK(60 == res.value().ttl());
  CHECK(0 < res.value().lease());
@ -96,6 +105,7 @@ TEST_CASE("sync operations") {
  res = etcd.set("/test/key1", "43", leaseid);
  REQUIRE(0 == res.error_code());
  CHECK("set" == res.action());
+  res = etcd.get("/test/key1");
  CHECK(leaseid == res.value().lease());

  // modify with lease
--- a/tst/EtcdTest.cpp
+++ b/tst/EtcdTest.cpp
@ -91,12 +91,13 @@ TEST_CASE("set a key") {
  CHECK(0 == etcd.set("/test", "42").get().error_code());  // Not a file

  // set with ttl
-  resp = etcd.set("/test/key1", "50", 10).get();
+  resp = etcd.set("/test/key1", "50").get();
  REQUIRE(0 == resp.error_code());  // overwrite
  CHECK("set" == resp.action());
  CHECK("43" == resp.prev_value().as_string());
+  resp = etcd.get("/test/key1").get();
  CHECK("50" == resp.value().as_string());
-  CHECK(0 < resp.value().lease());
+  CHECK(0 == resp.value().lease());
 }

 TEST_CASE("atomic compare-and-swap") {
@ -115,11 +116,11 @@ TEST_CASE("atomic compare-and-swap") {
  CHECK(etcd::ERROR_COMPARE_FAILED == res.error_code());
  CHECK("etcd-cpp-apiv3: compare failed" == res.error_message());

-  // modify fails the second time
+  // modify fails on non-existing keys
  res = etcd.modify_if("/test/key222", "44", "42").get();
  CHECK(!res.is_ok());
-  CHECK(etcd::ERROR_KEY_NOT_FOUND == res.error_code());
-  CHECK("etcd-cpp-apiv3: key not found" == res.error_message());
+  CHECK(etcd::ERROR_COMPARE_FAILED == res.error_code());
+  CHECK("etcd-cpp-apiv3: compare failed" == res.error_message());
 }

 TEST_CASE("delete a value") {
@ -144,10 +145,10 @@ TEST_CASE("delete a value") {
  CHECK(modify_index == resp.prev_value().modified_index());
  CHECK(version == resp.prev_value().version());
  CHECK("delete" == resp.action());
-  CHECK(modify_index == resp.value().modified_index());
  CHECK(create_index == resp.value().created_index());
+  CHECK(modify_index == resp.value().modified_index());
  CHECK(version == resp.value().version());
-  CHECK("" == resp.value().as_string());
+  CHECK("43" == resp.value().as_string());
  CHECK("/test/key1" == resp.value().key());
 }

@ -558,6 +559,8 @@ TEST_CASE("lease grant") {
  res = etcd.set("/test/key1", "43", leaseid).get();
  REQUIRE(0 == res.error_code());  // overwrite
  CHECK("set" == res.action());
+  res = etcd.get("/test/key1").get();
+  REQUIRE(0 == res.error_code());  // overwrite
  CHECK(leaseid == res.value().lease());

  // change with lease id
@ -566,6 +569,8 @@ TEST_CASE("lease grant") {
  res = etcd.set("/test/key1", "43", leaseid).get();
  REQUIRE(0 == res.error_code());  // overwrite
  CHECK("set" == res.action());
+  res = etcd.get("/test/key1").get();
+  REQUIRE(0 == res.error_code());  // overwrite
  CHECK(leaseid == res.value().lease());

  // failure to attach lease id
--- a/tst/KeepAliveTest.cpp
+++ b/tst/KeepAliveTest.cpp
@ -31,7 +31,9 @@ TEST_CASE("keepalive revoke and check if alive") {
  std::this_thread::sleep_for(std::chrono::seconds(1));

  // expect keep_alive->Check() to throw exception
+#ifndef _ETCD_NO_EXCEPTIONS
  REQUIRE_THROWS(keepalive->Check());
+#endif
 }

 TEST_CASE("keepalive won't expire") {
@ -45,6 +47,7 @@ TEST_CASE("keepalive won't expire") {
  auto lease_id = resp.value().lease();
  etcd.add(key, meta_str, lease_id);

+#ifndef _ETCD_NO_EXCEPTIONS
  std::function<void(std::exception_ptr)> handler =
      [](std::exception_ptr eptr) {
        try {
@ -57,6 +60,22 @@ TEST_CASE("keepalive won't expire") {
          std::cerr << "Lease expiry \"" << e.what() << "\"\n";
        }
      };
+#else
+  std::function<void(std::exception_ptr)> handler;
+#endif
  etcd::KeepAlive keepalive(etcd, handler, ttl, lease_id);
  std::this_thread::sleep_for(std::chrono::seconds(5));
 }
+
+TEST_CASE("keepalive auto-grant") {
+  etcd::Client etcd(etcd_uri);
+
+  // create a lease without pre-granted lease id
+  auto keepalive = std::make_shared<etcd::KeepAlive>(etcd, 10 /* ttl */);
+  auto lease_id = keepalive->Lease();
+  REQUIRE(lease_id != 0);
+
+  // sleep for a while, and cancel
+  std::this_thread::sleep_for(std::chrono::seconds(5));
+  keepalive->Cancel();
+}
--- a/tst/LockTest.cpp
+++ b/tst/LockTest.cpp
@ -117,6 +117,7 @@ TEST_CASE("lock using lease") {

  bool failed = false;

+#ifndef _ETCD_NO_EXCEPTIONS
  std::function<void(std::exception_ptr)> handler =
      [&failed](std::exception_ptr eptr) {
        try {
@ -128,6 +129,9 @@ TEST_CASE("lock using lease") {
          failed = true;
        }
      };
+#else
+  std::function<void(std::exception_ptr)> handler;
+#endif

  // with handler
  {
--- a/tst/MemLeakTest.cpp
+++ b/tst/MemLeakTest.cpp
@ -24,7 +24,6 @@ class DistributedLock {
 DistributedLock::DistributedLock(const std::string& lock_name, uint timeout) {
  _etcd_client = std::unique_ptr<etcd::Client>(new etcd::Client(etcd_url));

-  try {
  if (timeout == 0) {
    etcd::Response resp = _etcd_client->lock(lock_name).get();
    if (resp.is_ok()) {
@ -32,14 +31,12 @@ DistributedLock::DistributedLock(const std::string& lock_name, uint timeout) {
      _acquired = true;
    }
  } else {
-      std::future<etcd::Response> future =
-          std::async(std::launch::async, [&]() {
+    std::future<etcd::Response> future = std::async(std::launch::async, [&]() {
      etcd::Response resp = _etcd_client->lock(lock_name).get();
      return resp;
    });

-      std::future_status status =
-          future.wait_for(std::chrono::seconds(timeout));
+    std::future_status status = future.wait_for(std::chrono::seconds(timeout));
    if (status == std::future_status::ready) {
      auto resp = future.get();
      if (resp.is_ok()) {
@ -53,9 +50,6 @@ DistributedLock::DistributedLock(const std::string& lock_name, uint timeout) {
      std::cerr << "failed to acquire distributed lock" << std::endl;
    }
  }
-  } catch (std::exception& e) {
-    std::cerr << "failed to construct: " << e.what() << std::endl;
-  }
 }

 DistributedLock::~DistributedLock() noexcept {
@ -63,14 +57,10 @@ DistributedLock::~DistributedLock() noexcept {
    return;
  }

-  try {
  auto resp = _etcd_client->unlock(_lock_key).get();
  if (!resp.is_ok()) {
    std::cout << resp.error_code() << std::endl;
  }
-  } catch (std::exception& e) {
-    std::cerr << "failed to destruct: " << e.what() << std::endl;
-  }
 }

 int main() {
--- a/tst/RewatchTest.cpp
+++ b/tst/RewatchTest.cpp
@ -37,6 +37,7 @@ void print_response(etcd::Response const& resp) {
 void wait_for_connection(std::string endpoints) {
  // wait until the client connects to etcd server
  while (true) {
+#ifndef _ETCD_NO_EXCEPTIONS
    try {
      etcd::Client client(endpoints);
      if (client.head().get().is_ok()) {
@ -45,6 +46,12 @@ void wait_for_connection(std::string endpoints) {
    } catch (...) {
      // pass
    }
+#else
+    etcd::Client client(endpoints);
+    if (client.head().get().is_ok()) {
+      break;
+    }
+#endif
    sleep(1);
  }
 }
@ -85,6 +92,7 @@ TEST_CASE("watch should can be re-established") {

  // issue some changes to see if the watcher works
  for (int round = 0; round < 100000; ++round) {
+#ifndef _ETCD_NO_EXCEPTIONS
    try {
      etcd::Client client(etcd_url);
      auto response =
@ -92,6 +100,11 @@ TEST_CASE("watch should can be re-established") {
    } catch (...) {
      // pass
    }
+#else
+    etcd::Client client(etcd_url);
+    auto response =
+        client.set(my_prefix + "/foo", "bar-" + std::to_string(round)).get();
+#endif

    std::this_thread::sleep_for(std::chrono::seconds(2));
  }
@ -101,6 +114,7 @@ TEST_CASE("watch should can be re-established") {

  // the watcher has been cancelled and shouldn't work anymore
  for (int round = 10; round < 20; ++round) {
+#ifndef _ETCD_NO_EXCEPTIONS
    try {
      etcd::Client client(etcd_url);
      auto response =
@ -108,6 +122,11 @@ TEST_CASE("watch should can be re-established") {
    } catch (...) {
      // pass
    }
+#else
+    etcd::Client client(etcd_url);
+    auto response =
+        client.set(my_prefix + "/foo", "bar-" + std::to_string(round)).get();
+#endif

    std::this_thread::sleep_for(std::chrono::seconds(2));
  }
--- a/tst/TransactionTest.cpp
+++ b/tst/TransactionTest.cpp
@ -50,13 +50,8 @@ TEST_CASE("add a new key") {
    etcdv3::Transaction txn;

    // setup the conditions
-    txn.reset_key("/test/x1");
-    txn.init_compare("1", etcdv3::CompareResult::EQUAL,
-                     etcdv3::CompareTarget::VALUE);
-
-    txn.reset_key("/test/x2");
-    txn.init_compare("2", etcdv3::CompareResult::EQUAL,
-                     etcdv3::CompareTarget::VALUE);
+    txn.add_compare_value("/test/x1", "1");
+    txn.add_compare_value("/test/x2", "2");

    txn.setup_put("/test/x1", "111");
    txn.setup_delete("/test/x2");
@ -84,6 +79,51 @@ TEST_CASE("add a new key") {
  }
 }

+TEST_CASE("fetch & add") {
+  etcd::Client etcd(etcd_url);
+  etcd.rmdir("/test", true).wait();
+
+  etcd.set("/test/key", "0").wait();
+
+  auto fetch_and_add = [](etcd::Client& client,
+                          std::string const& key) -> void {
+    auto value = stoi(client.get(key).get().value().as_string());
+    while (true) {
+      auto txn = etcdv3::Transaction();
+      txn.setup_compare_and_swap(key, std::to_string(value),
+                                 std::to_string(value + 1));
+      etcd::Response resp = client.txn(txn).get();
+      if (resp.is_ok()) {
+        break;
+      }
+      value = stoi(resp.value().as_string());
+    }
+  };
+
+  // run 1000 times
+  const size_t rounds = 100;
+  std::atomic_size_t counter(0);
+
+  std::vector<std::thread> threads;
+  for (size_t i = 0; i < 10; ++i) {
+    threads.emplace_back([&]() {
+      while (counter.fetch_add(1) < rounds) {
+        fetch_and_add(etcd, "/test/key");
+      }
+    });
+  }
+  for (auto& thr : threads) {
+    thr.join();
+  }
+
+  // check the value
+  {
+    etcd::Response resp = etcd.get("/test/key").get();
+    REQUIRE(0 == resp.error_code());
+    CHECK(resp.value().as_string() == std::to_string(rounds));
+  }
+}
+
 TEST_CASE("cleanup") {
  etcd::Client etcd(etcd_url);
  REQUIRE(0 == etcd.rmdir("/test", true).get().error_code());
--- a/tst/WatcherTest.cpp
+++ b/tst/WatcherTest.cpp
@ -191,6 +191,41 @@ TEST_CASE("create two watcher") {
  std::this_thread::sleep_for(std::chrono::seconds(5));
 }

+TEST_CASE("using two watcher") {
+  etcd::SyncClient etcd(etcd_url);
+
+  int watched1 = 0;
+  int watched2 = 0;
+
+  etcd::Watcher w1(
+      etcd, "/test/def",
+      [&](etcd::Response const& resp) {
+        std::cout << "w1 called: " << resp.events().at(0).event_type() << " on "
+                  << resp.events().at(0).kv().key() << std::endl;
+        ++watched1;
+      },
+      true);
+  etcd::Watcher w2(
+      etcd, "/test",
+      [&](etcd::Response const& resp) {
+        std::cout << "w2 called: " << resp.events().at(0).event_type() << " on "
+                  << resp.events().at(0).kv().key() << std::endl;
+        ++watched2;
+      },
+      true);
+
+  std::this_thread::sleep_for(std::chrono::seconds(5));
+
+  etcd.put("/test/def/xxx", "42");
+  etcd.put("/test/abc", "42");
+  etcd.rm("/test/def/xxx");
+  etcd.rm("/test/abc");
+
+  std::this_thread::sleep_for(std::chrono::seconds(5));
+  CHECK(2 == watched1);
+  CHECK(4 == watched2);
+}
+
 // TEST_CASE("request cancellation")
 // {
 //   etcd::Client etcd(etcd_url);
Author	SHA1	Message	Date
holobay	5994b54c68	Bump up the version to v0.15.5	2025-04-01 23:16:01 +03:00
Tao He	ba6216385f	Bump up the version to v0.15.4 Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-12-20 18:28:15 +08:00
Tao He	5ccaccec43	Enable ipv6 endpoints support (#262 ) Resolves #250 Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-12-20 17:56:18 +08:00
Tao He	b82efea7a9	Enable -fno-exceptions support (#261 ) Resolves #259 Signed-off-by: Tao He <sighingnow@gmail.com>	2023-12-20 09:18:10 +08:00
Tao He	5aff57cce5	Fixes the noisy logs when meets invalid addresses. (#260 ) Signed-off-by: Tao He <sighingnow@gmail.com>	2023-12-20 00:32:00 +08:00
penfree	84343ca9f0	Fix: keepalive exit without any message due to clock drift (#258 ) Fix: #257 Co-authored-by: qiupengfei <qiupengfei@baidu.com>	2023-12-19 23:45:19 +08:00
Diskein	59635008c0	Fixes compiler errors (#254 ) Co-authored-by: Denis Kalantaevsky <dkalantaevsky@gmail.com> Co-authored-by: Tao He <sighingnow@gmail.com>	2023-10-05 22:59:06 -05:00
Clément Péron	47f0d9e032	cmake: fix when cross compiling (#252 ) To compile protobuf, CMake needs to use the protoc and grpc-cpp-plugin in the host architecture. Unfortunately by default the protoc and grpc-cpp-plugin are the one for the Target. And since gRPC 1.52 they are explictly not exported when Cross Compiling to avoid architecture mismatch. See: `831d2a6855` Fix this by looking at the correct program See example. https://github.com/grpc/grpc/blob/master/examples/cpp/cmake/common.cmake#L54-L62 Signed-off-by: Clément Péron <peron.clem@gmail.com>	2023-09-25 09:49:24 +08:00
Tao He	6fc1f164c0	Fixes the extra-smi error in code generated by protobuf (#251 ) Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-09-19 20:42:49 +08:00
Tao He	e31ac4d4ca	Bump up etcd-cpp-apiv3 to v0.15.3 Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-07-27 11:28:00 +08:00
JonLiu1993	e5dc903a5d	Fix error LNK1107 and undeclared identifier 'IPPROTO_TCP' (#244 ) When I [Update](https://github.com/microsoft/vcpkg/pull/32747) etcd-cpp-apiv3 version from 0.14.2 to 0.15.2, I get two build error: ```` fatal error LNK1107: invalid or corrupt file: cannot read at 0x330 ```` ```` error: use of undeclared identifier 'IPPROTO_TCP' ```` The first error was because the target `etcd-cpp-api-core-objects` linked the wrong `libprotobufd.dll` file instead of the .lib file, I used the usage provided by vcpkg to link the correct .lib file to fix this error. Another error was because `IPPROTO_TCP` was missing declaration `"<netinet/in.h>"`, I added it to fix this error. --------- Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com> Co-authored-by: Zhao Liu <v-zhli17@microsoft.com> Co-authored-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-07-27 11:27:19 +08:00
Tao He	0eee75b52e	KeepAlive: auto grant a new lease if 0 is given as lease id (#242 ) Fixes #3037 Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-07-20 14:21:27 +08:00
Tao He	15c022e36c	Bump up etcd-cpp-apiv3 to v0.15.2 Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-07-17 10:44:06 +08:00
Tao He	3d344190d7	Fixes txn delete response to keep backwards compatibility (#239 ) Signed-off-by: Tao He <linzhu.ht@alibaba-inc.com>	2023-07-17 10:43:19 +08:00
Tao He	2c0d824ebe	Bump up etcd-cpp-apiv3 to v0.15.1 Signed-off-by: Tao He <sighingnow@gmail.com>	2023-07-15 20:23:01 +08:00
Tao He	068f37ba5c	Fixes the watcher cannot be cancelled issue with etcd 3.x (#238 ) Signed-off-by: Tao He <sighingnow@gmail.com>	2023-07-15 20:00:16 +08:00
Tao He	153546f965	Refactor the implementation of etcd transactions. (#236 ) Fixes #234. Signed-off-by: Tao He <sighingnow@gmail.com>	2023-07-15 17:07:34 +08:00
Tao He	204038c4bc	Fixes format issues Signed-off-by: Tao He <sighingnow@gmail.com>	2023-07-01 21:03:20 +08:00