Refactor the implementation of etcd transactions.

Signed-off-by: Tao He <sighingnow@gmail.com>

README.md

@@ -495,6 +495,7 @@ 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(std::string const& key)` unconditionally deletes the given key
 * `rm_if(key, value, 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`)
@@ -852,11 +853,32 @@ 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.add_compare_value("/test/x1", "1");
-  txn.init_compare("1", etcdv3::CompareResult::EQUAL, etcdv3::CompareTarget::VALUE);
+  txn.add_compare_value("/test/x2", "2");
 
-  txn.reset_key("/test/x2");
+  // or, compare the last modified revision
-  txn.init_compare("2", etcdv3::CompareResult::EQUAL, etcdv3::CompareTarget::VALUE);
+  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),

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);
+                           const int64_t leaseId = 0);
-
-  /**
-   * 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);
 
   /**
    * 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.
+   * Put a new key-value pair.
-   * @param key is the key to be modified
+   * @param key is the key to be put
-   * @param value is the new value to be set
+   * @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,
+  pplx::task<Response> put(std::string const& key, std::string const& value,
-                              int ttl = 0);
+                           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);
+                              const int64_t leaseId = 0);
-
-  /**
-   * 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);
 
   /**
    * 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);
+                                 std::string const& old_value,
-
+                                 const int64_t leaseId = 0);
-  /**
-   * 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);
 
   /**
    * Modifies an existing key only if it has a specific modification index
@@ -377,7 +339,7 @@ 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.

etcd/SyncClient.hpp

@@ -327,14 +327,6 @@ 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 +335,7 @@ class SyncClient {
    * @param leaseId is the lease attached to the key
    */
   Response set(std::string const& key, std::string const& value,
-               int64_t leaseId);
+               const int64_t leaseId = 0);
-
-  /**
-   * 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);
 
   /**
    * Creates a new key and sets it's value. Fails if the key already exists.
@@ -359,7 +344,7 @@ 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 +354,13 @@ class SyncClient {
   Response put(std::string const& key, std::string const& value);
 
   /**
-   * Modifies an existing key. Fails if the key does not exists.
+   * Put a new key-value pair.
-   * @param key is the key to be modified
+   * @param key is the key to be put
-   * @param value is the new value to be set
+   * @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,
+  Response put(std::string const& key, std::string const& value,
-                  int ttl = 0);
+               const int64_t leaseId);
 
   /**
    * Modifies an existing key. Fails if the key does not exists.
@@ -383,17 +369,7 @@ class SyncClient {
    * @param leaseId is the lease attached to the key
    */
   Response modify(std::string const& key, std::string const& value,
-                  int64_t leaseId);
+                  const int64_t leaseId = 0);
-
-  /**
-   * 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);
 
   /**
    * Modifies an existing key only if it has a specific value. Fails if the key
@@ -404,18 +380,7 @@ 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);
+                     std::string const& old_value, const int64_t leaseId = 0);
-
-  /**
-   * 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);
 
   /**
    * Modifies an existing key only if it has a specific modification index
@@ -427,7 +392,7 @@ 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.
@@ -819,22 +784,21 @@ 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,
+  std::shared_ptr<etcdv3::AsyncRangeAction> get_internal(
-                                                         int64_t revision = 0);
+      std::string const& key, const int64_t revision = 0);
-  std::shared_ptr<etcdv3::AsyncSetAction> set_internal(std::string const& key,
+  std::shared_ptr<etcdv3::AsyncSetAction> add_internal(
-                                                       std::string const& value,
+      std::string const& key, std::string const& value,
-                                                       int64_t leaseId);
+      const int64_t leaseId = 0);
-  std::shared_ptr<etcdv3::AsyncSetAction> add_internal(std::string const& key,
-                                                       std::string const& value,
-                                                       int64_t leaseId);
   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,
+      std::string const& old_value, etcdv3::AtomicityType const& atomicity_type,
-      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(

etcd/v3/Action.hpp

@@ -9,6 +9,8 @@
 #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;
@@ -81,6 +83,27 @@ 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

etcd/v3/AsyncGRPC.hpp

@@ -76,8 +76,7 @@ class AsyncCampaignResponse : public etcdv3::V3Response {
 class AsyncDeleteResponse : public etcdv3::V3Response {
  public:
   AsyncDeleteResponse(){};
-  void ParseResponse(std::string const& key, bool prefix,
+  void ParseResponse(bool prefix, DeleteRangeResponse& resp);
-                     DeleteRangeResponse& resp);
 };
 
 class AsyncHeadResponse : public etcdv3::V3Response {
@@ -162,7 +161,6 @@ 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 {

etcd/v3/Transaction.hpp

@@ -28,38 +28,194 @@ enum class CompareTarget {
 class Transaction {
  public:
   Transaction();
-  Transaction(std::string const&);
+  ~Transaction();
-  virtual ~Transaction();
 
-  // Set a new key for different comparisons and /put/get/delete requests.
+  union Value {
-  void reset_key(std::string const& newkey);
+    int64_t version;
+    int64_t create_revision;
+    int64_t mod_revision;
+    std::string value;
+    int64_t lease;
+  };
 
-  void init_compare(CompareResult, CompareTarget);
+  void add_compare(std::string const& key, CompareTarget const& target,
-  void init_compare(std::string const& old_value, CompareResult, CompareTarget);
+                   CompareResult const& result, Value const& target_value,
-  void init_compare(int64_t old_value, CompareResult, CompareTarget);
+                   std::string const& range_end = "");
 
-  void setup_basic_failure_operation(std::string const& key);
+  void add_compare_version(std::string const& key, int64_t const& version,
-  void setup_set_failure_operation(std::string const& key,
+                           std::string const& range_end = "");
-                                   std::string const& value, int64_t leaseid);
+  void add_compare_version(std::string const& key, CompareResult const& result,
-  void setup_basic_create_sequence(std::string const& key,
+                           int64_t const& version,
-                                   std::string const& value, int64_t leaseid);
+                           std::string const& range_end = "");
-  void setup_compare_and_swap_sequence(std::string const& valueToSwap,
+  void add_compare_create(std::string const& key,
-                                       int64_t leaseid);
+                          int64_t const& create_revision,
-  void setup_delete_sequence(std::string const& key,
+                          std::string const& range_end = "");
-                             std::string const& range_end, bool recursive);
+  void add_compare_create(std::string const& key, CompareResult const& result,
-  void setup_delete_failure_operation(std::string const& key,
+                          int64_t const& create_revision,
-                                      std::string const& range_end,
+                          std::string const& range_end = "");
-                                      bool recursive);
+  void add_compare_mod(std::string const& key, int64_t const& mod_revision,
-  void setup_compare_and_delete_operation(std::string const& key);
+                       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

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) {
+                                             const int64_t leaseid) {
-  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>>(
+      static_cast<responser_t<etcdv3::AsyncPutAction>>(Response::create),
-                    Response::create),
+      this->client->put_internal(key, value, leaseid));
-                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));
 }
 
 pplx::task<etcd::Response> etcd::Client::add(std::string const& key,
                                              std::string const& value,
-                                             int ttl) {
+                                             const int64_t leaseid) {
-  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) {
   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) {
+                                             const int64_t leaseId) {
-  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::AsyncUpdateAction>>(
+      static_cast<responser_t<etcdv3::AsyncPutAction>>(Response::create),
-                    Response::create),
+      this->client->put_internal(key, value, leaseId));
-                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));
-  }
 }
 
 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) {
+                                                   const int64_t leaseid) {
-  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) {
   return etcd::detail::asyncify(
       static_cast<responser_t<etcdv3::AsyncCompareAndSwapAction>>(
           Response::create),
-                this->client->modify_if_internal(
+      this->client->modify_if_internal(key, value, 0, old_value,
-                    key, value, 0, old_value, resp.value().lease(),
+                                       etcdv3::AtomicityType::PREV_VALUE,
-                    etcdv3::AtomicityType::PREV_VALUE));
+                                       leaseid));
-          } 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));
-  }
 }
 
 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,
+      this->client->modify_if_internal(key, value, old_index, "",
-                                       etcdv3::AtomicityType::PREV_INDEX));
+                                       etcdv3::AtomicityType::PREV_INDEX,
+                                       leaseid));
 }
 
 pplx::task<etcd::Response> etcd::Client::rm(std::string const& key) {

src/Response.cpp

@@ -39,6 +39,7 @@ 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());
   }

src/SyncClient.cpp

@@ -474,18 +474,6 @@ 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 +490,8 @@ 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 +507,20 @@ 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) {
+                                     const int64_t leaseid) {
-  return Response::create(this->set_internal(key, value, leaseid));
+  return Response::create(this->put_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));
 }
 
 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 +536,32 @@ 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 +575,23 @@ 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) {
+                                           const int64_t leaseid) {
-  // 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, 0, old_value, leaseId, etcdv3::AtomicityType::PREV_VALUE));
+      key, value, 0, old_value, etcdv3::AtomicityType::PREV_VALUE, leaseid));
-}
-
-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));
 }
 
 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,
+    std::string const& old_value, etcdv3::AtomicityType const& atomicity_type,
-    etcdv3::AtomicityType const& atomicity_type) {
+    const int64_t leaseId) {
   etcdv3::ActionParameters params;
   params.key.assign(key);
   params.value.assign(value);

src/v3/AsyncGRPC.cpp

@@ -43,8 +43,7 @@ void etcdv3::AsyncCampaignResponse::ParseResponse(CampaignResponse& reply) {
   value.kvs.set_lease(leader.lease());
 }
 
-void etcdv3::AsyncDeleteResponse::ParseResponse(std::string const& key,
+void etcdv3::AsyncDeleteResponse::ParseResponse(bool prefix,
-                                                bool prefix,
                                                 DeleteRangeResponse& resp) {
   index = resp.header().revision();
 
@@ -167,38 +166,72 @@ 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();
+      }
-
+      if (!response.get_error_message().empty()) {
-      values = response.get_values();
+        error_message += "\n" + response.get_error_message();
-      value = response.get_value();
+      }
+      for (auto const& value : response.get_values()) {
+        values.emplace_back(value);
+      }
     } else if (ResponseOp::ResponseCase::kResponsePut == resp.response_case()) {
-      auto put_resp = resp.response_put();
+      AsyncPutResponse response;
-      if (put_resp.has_prev_kv()) {
+      response.ParseResponse(*(resp.mutable_response_put()));
-        prev_value.kvs.CopyFrom(put_resp.prev_kv());
+      prev_value.kvs.CopyFrom(response.get_prev_value().kvs);
+
+      if (error_code == 0) {
+        error_code = response.get_error_code();
+      }
+      if (!response.get_error_message().empty()) {
+        error_message += "\n" + response.get_error_message();
+      }
+      for (auto const& value : response.get_values()) {
+        values.emplace_back(value);
       }
     } else if (ResponseOp::ResponseCase::kResponseDeleteRange ==
                resp.response_case()) {
       AsyncDeleteResponse response;
-      response.ParseResponse(key, prefix,
+      response.ParseResponse(true, *(resp.mutable_response_delete_range()));
-                             *(resp.mutable_response_delete_range()));
-
       prev_value.kvs.CopyFrom(response.get_prev_value().kvs);
 
-      values = response.get_values();
+      if (error_code == 0) {
-      value = response.get_value();
+        error_code = response.get_error_code();
       }
+      if (!response.get_error_message().empty()) {
+        error_message += "\n" + response.get_error_message();
+      }
+      for (auto const& value : response.get_values()) {
+        values.emplace_back(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()) {
+        error_message += "\n" + response.get_error_message();
+      }
+
+      // skip
+      std::cerr << "Not implemented error: unable to parse nested transaction "
+                   "response"
+                << std::endl;
+    }
+  }
+  if (!values.empty()) {
+    value = values[0];
+  }
+  if (!prev_values.empty()) {
+    prev_value = prev_values[0];
   }
 }
 
@@ -270,20 +303,17 @@ 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,
+    txn.setup_compare_and_delete(parameters.key, parameters.old_value,
-                             CompareTarget::VALUE);
+                                 parameters.key);
   } else if (type == etcdv3::AtomicityType::PREV_INDEX) {
-    transaction.init_compare(parameters.old_revision, CompareResult::EQUAL,
+    txn.setup_compare_and_delete(parameters.key, parameters.old_revision,
-                             CompareTarget::MOD);
+                                 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 +325,30 @@ 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,
+    txn.setup_compare_and_swap(parameters.key, parameters.old_value,
-                             CompareTarget::VALUE);
+                               parameters.value);
   } else if (type == etcdv3::AtomicityType::PREV_INDEX) {
-    transaction.init_compare(parameters.old_revision, CompareResult::EQUAL,
+    txn.setup_compare_and_swap(parameters.key, parameters.old_revision,
-                             CompareTarget::MOD);
+                               parameters.value);
   }
 
-  transaction.setup_basic_failure_operation(parameters.key);
-  transaction.setup_compare_and_swap_sequence(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);
 }
 
@@ -335,7 +360,7 @@ 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.
@@ -344,29 +369,14 @@ 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) {
+  detail::make_request_with_ranges(del_request, parameters.key,
-    del_request.set_key(parameters.key);
+                                   parameters.range_end, parameters.withPrefix);
-  } 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);
 
   response_reader =
@@ -383,10 +393,8 @@ etcdv3::AsyncDeleteResponse etcdv3::AsyncDeleteAction::ParseResponse() {
     del_resp.set_error_message(status.error_message());
   } else {
     del_resp.ParseResponse(
-        parameters.key, parameters.withPrefix || !parameters.range_end.empty(),
+        parameters.withPrefix || !parameters.range_end.empty(), reply);
-        reply);
   }
-
   return del_resp;
 }
 
@@ -874,21 +882,8 @@ etcdv3::AsyncPutResponse etcdv3::AsyncPutAction::ParseResponse() {
 etcdv3::AsyncRangeAction::AsyncRangeAction(etcdv3::ActionParameters&& params)
     : etcdv3::Action(std::move(params)) {
   RangeRequest get_request;
-  if (!parameters.withPrefix) {
+  detail::make_request_with_ranges(get_request, parameters.key,
-    get_request.set_key(parameters.key);
+                                   parameters.range_end, parameters.withPrefix);
-  } 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);
-  }
   if (parameters.revision > 0) {
     get_request.set_revision(parameters.revision);
   }
@@ -951,21 +946,17 @@ 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);
+  txn.add_compare_mod(parameters.key, 0 /* not exists */);
-
+  txn.add_success_put(parameters.key, parameters.key, parameters.lease_id);
-  transaction.setup_basic_create_sequence(parameters.key, parameters.value,
+  if (create) {
-                                          parameters.lease_id);
+    txn.add_failure_put(parameters.key, parameters.value, parameters.lease_id);
-
-  if (isCreate) {
-    transaction.setup_basic_failure_operation(parameters.key);
   } else {
-    transaction.setup_set_failure_operation(parameters.key, parameters.value,
+    txn.add_failure_range(parameters.key);
-                                            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 +968,7 @@ 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 +994,7 @@ 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 +1033,12 @@ etcdv3::AsyncUnlockResponse etcdv3::AsyncUnlockAction::ParseResponse() {
 
 etcdv3::AsyncUpdateAction::AsyncUpdateAction(etcdv3::ActionParameters&& params)
     : etcdv3::Action(std::move(params)) {
-  etcdv3::Transaction transaction(parameters.key);
+  etcdv3::Transaction txn;
-  transaction.init_compare(CompareResult::GREATER, CompareTarget::VERSION);
+  txn.add_compare_version(parameters.key, CompareResult::GREATER, 0);  // exists
-
+  txn.add_success_put(parameters.key, parameters.value, parameters.lease_id);
-  transaction.setup_compare_and_swap_sequence(parameters.value,
+  txn.add_failure_range(parameters.key);
-                                              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);
 }
 
@@ -1061,7 +1050,7 @@ 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);
@@ -1084,22 +1073,8 @@ etcdv3::AsyncWatchAction::AsyncWatchAction(etcdv3::ActionParameters&& params)
 
   WatchRequest watch_req;
   WatchCreateRequest watch_create_req;
-
+  detail::make_request_with_ranges(watch_create_req, parameters.key,
-  if (!parameters.withPrefix) {
+                                   parameters.range_end, 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);
-  }
-
   watch_create_req.set_prev_kv(true);
   watch_create_req.set_start_revision(parameters.revision);
   watch_create_req.set_watch_id(this->watch_id);

src/v3/Transaction.cpp

@@ -2,11 +2,7 @@
 
 #include "proto/rpc.grpc.pb.h"
 
-using etcdserverpb::Compare;
+#include "etcd/v3/Action.hpp"
-using etcdserverpb::DeleteRangeRequest;
-using etcdserverpb::PutRequest;
-using etcdserverpb::RangeRequest;
-using etcdserverpb::RequestOp;
 
 namespace etcdv3 {
 
@@ -28,185 +24,331 @@ etcdv3::Transaction::Transaction() {
   txn_request.reset(new etcdserverpb::TxnRequest{});
 }
 
-etcdv3::Transaction::Transaction(const std::string& key) : key(key) {
+etcdv3::Transaction::~Transaction() {}
-  txn_request.reset(new etcdserverpb::TxnRequest{});
+
+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,
+void etcdv3::Transaction::add_compare_version(std::string const& key,
-                                       CompareTarget target) {
+                                              CompareResult const& result,
-  Compare* compare = txn_request->add_compare();
+                                              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(version);
-  compare->set_version(0);
+  compare->set_range_end(range_end);
 }
 
-void etcdv3::Transaction::init_compare(std::string const& old_value,
+void etcdv3::Transaction::add_compare_create(std::string const& key,
-                                       CompareResult result,
+                                             int64_t const& create_revision,
-                                       CompareTarget target) {
+                                             std::string const& range_end) {
-  Compare* compare = txn_request->add_compare();
+  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_create_revision(create_revision);
-  compare->set_value(old_value);
+  compare->set_range_end(range_end);
 }
 
-void etcdv3::Transaction::init_compare(int64_t old_index, CompareResult result,
+void etcdv3::Transaction::add_compare_mod(std::string const& key,
-                                       CompareTarget target) {
+                                          int64_t const& mod_revision,
-  Compare* compare = txn_request->add_compare();
+                                          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(mod_revision);
-  compare->set_mod_revision(old_index);
+  compare->set_range_end(range_end);
 }
 
-/**
+void etcdv3::Transaction::add_compare_value(std::string const& key,
- * 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,
                                             std::string const& value,
-                                                      int64_t leaseid) {
+                                            std::string const& range_end) {
-  std::unique_ptr<PutRequest> put_request(new PutRequest());
+  this->add_compare_value(key, CompareResult::EQUAL, value, range_end);
-  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());
 }
 
-/**
+void etcdv3::Transaction::add_compare_value(std::string const& key,
- * add key and then get new value of key
+                                            CompareResult const& result,
- */
-void etcdv3::Transaction::setup_basic_create_sequence(std::string const& key,
                                             std::string const& value,
-                                                      int64_t leaseid) {
+                                            std::string const& range_end) {
-  std::unique_ptr<PutRequest> put_request(new PutRequest());
+  auto compare = txn_request->add_compare();
-  put_request->set_key(key);
+  compare->set_result(detail::to_compare_result(result));
-  put_request->set_value(value);
+  compare->set_target(detail::to_compare_target(CompareTarget::VALUE));
-  put_request->set_prev_kv(true);
+  compare->set_key(key);
-  put_request->set_lease(leaseid);
+  compare->set_value(value);
-  RequestOp* req_success = txn_request->add_success();
+  compare->set_range_end(range_end);
-  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,
- * get key value then modify and get new value
+                                            int64_t const& lease,
- */
+                                            std::string const& range_end) {
-void etcdv3::Transaction::setup_compare_and_swap_sequence(
+  this->add_compare_lease(key, CompareResult::EQUAL, lease, range_end);
-    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,
- * get key, delete
+                                            CompareResult const& result,
- */
+                                            int64_t const& lease,
-void etcdv3::Transaction::setup_delete_sequence(std::string const& key,
+                                            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) {
+                                            bool const recursive,
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
+                                            const int64_t limit) {
-  del_request->set_key(key);
+  auto succ = txn_request->add_success();
-  del_request->set_prev_kv(true);
+  auto get_request = succ->mutable_request_range();
-  if (recursive) {
+  etcdv3::detail::make_request_with_ranges(*get_request, key, range_end,
-    del_request->set_range_end(range_end);
+                                           recursive);
-  }
+  get_request->set_limit(limit);
-
-  RequestOp* req_success = txn_request->add_success();
-  req_success->set_allocated_request_delete_range(del_request.release());
 }
 
-/**
+void etcdv3::Transaction::add_success_put(std::string const& key,
- * get key, delete
+                                          std::string const& value,
- */
+                                          int64_t const leaseid,
-void etcdv3::Transaction::setup_delete_failure_operation(
+                                          const bool prev_kv) {
-    std::string const& key, std::string const& range_end, bool recursive) {
+  auto succ = txn_request->add_success();
-  std::unique_ptr<RangeRequest> get_request(new RangeRequest());
+  auto put_request = succ->mutable_request_put();
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
+  put_request->set_key(key);
-  get_request.reset(new RangeRequest());
+  put_request->set_value(value);
-  get_request->set_key(key);
+  put_request->set_prev_kv(prev_kv);
-  if (recursive) {
+  put_request->set_lease(leaseid);
-    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::setup_compare_and_delete_operation(
+void etcdv3::Transaction::add_success_delete(std::string const& key,
-    std::string const& key) {
+                                             std::string const& range_end,
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
+                                             bool const recursive,
-  del_request->set_key(key);
+                                             const bool prev_kv) {
-  del_request->set_prev_kv(true);
+  auto succ = txn_request->add_success();
-  RequestOp* req_success = txn_request->add_success();
+  auto del_request = succ->mutable_request_delete_range();
-  req_success->set_allocated_request_delete_range(del_request.release());
+  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);
+  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);
+  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);
+  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);
+  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());
+  this->add_success_put(key, value);
-  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());
 }
 
 void etcdv3::Transaction::setup_delete(std::string const& key) {
-  std::unique_ptr<DeleteRangeRequest> del_request(new DeleteRangeRequest());
+  this->add_success_delete(key);
-  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());
 }
 
-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);
+}

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