Fixes memory leak issue inside the watcher (#197)

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

.github/workflows/build-test.yml

@@ -6,6 +6,9 @@ concurrency:
   group: ${{ github.repository }}-${{ github.event.number || github.head_ref || github.sha }}-${{ github.workflow }}
   cancel-in-progress: true
 
+env:
+  SEGFAULT_SIGNALS: all
+
 jobs:
   build:
     runs-on: ${{ matrix.os }}
@@ -129,6 +132,10 @@ jobs:
                               libgrpc++-dev \
                               protobuf-compiler-grpc
 
+          # install libsegfault.so
+          sudo apt-get install libc6 || true
+          sudo apt-get install glibc-tools || true
+
       - name: Install dependencies for Mac
         if: runner.os == 'macOS'
         run: |
@@ -172,6 +179,10 @@ jobs:
           make -j`nproc`
           sudo make install
 
+      - name: Setup tmate session
+        if: false
+        uses: mxschmitt/action-tmate@v3
+
       - name: Build
         run: |
           export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/lib:/usr/local/lib/x86_64-linux-gnu
@@ -211,12 +222,18 @@ jobs:
           echo "Run the etcd test ........................."
           ./build/bin/EtcdTest
 
+          echo "Run the etcd campaign test ........................."
+          ./build/bin/CampaignTest
+
           echo "Run the etcd memory leak test ........................."
           ./build/bin/MemLeakTest
 
           echo "Run the etcd watcher test ........................."
           ./build/bin/WatcherTest
 
+          echo "Run the etcd memory leak in watcher test ........................."
+          ./build/bin/MemLeakWatcherTest
+
           echo "Run the etcd keepalive test ........................."
           ./build/bin/KeepAliveTest
 

CMakeLists.txt

@@ -39,7 +39,7 @@ if(NOT "${ETCD_CMAKE_CXX_STANDARD}")
         set(ETCD_CMAKE_CXX_STANDARD ${CMAKE_CXX_STANDARD})
     endif()
 endif()
-message("Building etcd-cpp-apiv3 with C++${ETCD_CMAKE_CXX_STANDARD}")
+message(STATUS "Building etcd-cpp-apiv3 with C++${ETCD_CMAKE_CXX_STANDARD}")
 
 # reference: https://gitlab.kitware.com/cmake/community/-/wikis/doc/cmake/RPATH-handling#always-full-rpath
 set(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)
@@ -134,7 +134,7 @@ else()
     include(${CMAKE_CURRENT_SOURCE_DIR}/cmake/FindGRPC.cmake)
     set(GRPC_LIBRARIES ${GPR_LIBRARY} ${GRPC_LIBRARY} ${GRPC_GRPC++_LIBRARY})
 endif()
-message("-- Found GRPC: ${GRPC_LIBRARIES} (found version: \"${gRPC_VERSION}\")")
+message("-- Found GRPC: ${GRPC_LIBRARIES}, ${GRPC_CPP_PLUGIN} (found version: \"${gRPC_VERSION}\")")
 # avoid use the apt-get installed libgrpc-dev (version v1.13) on Ubuntu 18.04
 if(gRPC_FOUND AND gRPC_VERSION VERSION_LESS "1.14")
     message(FATAL_ERROR "gRPC '${gRPC_VERSION}' is not supported, please install a newer gRPC library "

etcd/SyncClient.hpp

@@ -42,6 +42,7 @@ namespace etcdv3 {
 
   namespace detail {
     std::string string_plus_one(std::string const &value);
+    std::string resolve_etcd_endpoints(std::string const &default_endpoints);
   }
 }
 

etcd/v3/Action.hpp

@@ -66,6 +66,8 @@ namespace etcdv3
   public:
     Action(etcdv3::ActionParameters const &params);
     Action(etcdv3::ActionParameters && params);
+    virtual ~Action();
+
     void waitForResponse();
     const std::chrono::high_resolution_clock::time_point startTimepoint();
   protected:
@@ -83,6 +85,7 @@ namespace etcdv3
 
   namespace detail {
     std::string string_plus_one(std::string const &value);
+    std::string resolve_etcd_endpoints(std::string const &default_endpoints);
   }
 }
 #endif

etcd/v3/AsyncWatchAction.hpp

@@ -26,6 +26,7 @@ namespace etcdv3
       void CancelWatch();
       bool Cancelled() const;
     private:
+      int64_t watch_id = -1;
       WatchResponse reply;
       std::unique_ptr<ClientAsyncReaderWriter<WatchRequest,WatchResponse>> stream;
       std::atomic_bool isCancelled;

etcd/v3/action_constants.hpp

@@ -34,10 +34,13 @@ namespace etcdv3
   extern char const * KEEPALIVE_WRITE;
   extern char const * KEEPALIVE_READ;
   extern char const * KEEPALIVE_DONE;
+  extern char const * KEEPALIVE_FINISH;
 
   extern char const * WATCH_CREATE;
   extern char const * WATCH_WRITE;
+  extern char const * WATCH_WRITE_CANCEL;
   extern char const * WATCH_WRITES_DONE;
+  extern char const * WATCH_FINISH;
 
   extern char const * ELECTION_OBSERVE_CREATE;
 

src/Watcher.cpp

@@ -11,6 +11,12 @@ struct etcd::Watcher::EtcdServerStubs {
 
 void etcd::Watcher::EtcdServerStubsDeleter::operator()(etcd::Watcher::EtcdServerStubs *stubs) {
   if (stubs) {
+    if (stubs->watchServiceStub) {
+      stubs->watchServiceStub.reset();
+    }
+    if (stubs->call) {
+      stubs->call.reset();
+    }
     delete stubs;
   }
 }

src/v3/Action.cpp

@@ -15,6 +15,13 @@ etcdv3::Action::Action(etcdv3::ActionParameters && params)
   this->InitAction();
 }
 
+etcdv3::Action::~Action() {
+  cq_.Shutdown();
+
+  // cancel on-the-fly calls
+  context.TryCancel();
+}
+
 void etcdv3::Action::InitAction() {
   if (!parameters.auth_token.empty()) {
     // use `token` as the key, see:
@@ -104,6 +111,10 @@ std::string etcdv3::detail::string_plus_one(std::string const &value) {
       return s;
     }
   }
-
   return {etcdv3::NUL};
 }
+
+std::string etcdv3::detail::resolve_etcd_endpoints(std::string const&default_endpoints) {
+  const char *ep = std::getenv("ETCD_ENDPOINTS");
+  return ep ? ep : default_endpoints;
+}

src/v3/AsyncLeaseAction.cpp

@@ -183,17 +183,23 @@ void etcdv3::AsyncLeaseKeepAliveAction::CancelKeepAlive()
     if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void *)etcdv3::KEEPALIVE_DONE) {
       // ok
     } else {
-      std::cerr << "Failed to mark a lease keep-alive connection as DONE" << std::endl;
+      std::cerr << "Failed to mark a lease keep-alive connection as DONE: "
+                << context.debug_error_string() << std::endl;
     }
 
     grpc::Status status;
-    stream->Finish(&status, (void *)this);
-    if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void *)this) {
+    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" << std::endl;
+      std::cerr << "Failed to finish a lease keep-alive connection: "
+                << status.error_message()
+                << ", " << context.debug_error_string() << std::endl;
     }
 
+    // cancel on-the-fly calls
+    context.TryCancel();
+
     cq_.Shutdown();
   }
 }

src/v3/AsyncWatchAction.cpp

@@ -2,8 +2,6 @@
 #include "etcd/v3/action_constants.hpp"
 
 
-using etcdserverpb::RangeRequest;
-using etcdserverpb::RangeResponse;
 using etcdserverpb::WatchCreateRequest;
 
 etcdv3::AsyncWatchAction::AsyncWatchAction(
@@ -45,6 +43,7 @@ etcdv3::AsyncWatchAction::AsyncWatchAction(
   // wait "write" (WatchCreateRequest) success, and start to read the first reply
   if (cq_.Next(&got_tag, &ok) && ok && got_tag == (void *)etcdv3::WATCH_WRITE) {
     stream->Read(&reply, (void*)this);
+    this->watch_id = reply.watch_id();
   } else {
     throw std::runtime_error("failed to write WatchCreateRequest to server");
   }
@@ -61,47 +60,60 @@ void etcdv3::AsyncWatchAction::waitForResponse()
     {
       break;
     }
-    if(isCancelled.load()) {
-      break;
+    if(got_tag == (void *)etcdv3::WATCH_WRITE_CANCEL) {
+      stream->WritesDone((void*)etcdv3::WATCH_WRITES_DONE);
+      continue;
     }
-    if(got_tag == (void*)etcdv3::WATCH_WRITES_DONE) {
-      isCancelled.store(true);
+    if(got_tag == (void*)etcdv3::WATCH_WRITES_DONE)
+    {
+      grpc::Status status;
+      stream->Finish(&status, (void *)etcdv3::WATCH_FINISH);
+      continue;
+    }
+    if (got_tag == (void *)etcdv3::WATCH_FINISH) {
+      // shutdown
       cq_.Shutdown();
+      // cancel on-the-fly calls
+      context.TryCancel();
       break;
     }
     if(got_tag == (void*)this) // read tag
     {
       if (reply.canceled()) {
-        isCancelled.store(true);
-        cq_.Shutdown();
-        break;
+        // cancel on-the-fly calls, but don't shutdown the completion queue as there
+        // are still a inflight call to finish
+        context.TryCancel();
+        // cq_.Shutdown();
+        continue;
       }
-      else if ((reply.created() && reply.header().revision() < parameters.revision) ||
-          reply.events_size() > 0) {
+
       // we stop watch under two conditions:
       //
       // 1. watch for a future revision, return immediately with empty events set
       // 2. receive any effective events.
-        isCancelled.store(true);
-
-        stream->WritesDone((void*)etcdv3::WATCH_WRITES_DONE);
-
-        grpc::Status status;
-        stream->Finish(&status, (void *)this);
-
-        cq_.Shutdown();
-
+      if ((reply.created() && reply.header().revision() < parameters.revision) ||
+          reply.events_size() > 0) {
         // leave a warning if the response is too large and been fragmented
         if (reply.fragment()) {
           std::cerr << "WARN: The response hasn't been fully received and parsed" << std::endl;
         }
-        break;
-      }
-      else
-      {
-        // otherwise, start next round read-reply
+
+        std::cout << "issue a watch cancel" << std::endl;
+        // cancel the watcher after receiving the good response
+        this->CancelWatch();
+
+        // start the next round to read finish messages, read into "&dummy"
+        // (use nullptr, as it won't be touched).
+        stream->Read(nullptr, (void*)etcdv3::WATCH_FINISH);
+      } else {
+        // start the next round to read reply, read into "&reply"
         stream->Read(&reply, (void*)this);
       }
+      continue;
+    }
+    if(isCancelled.load()) {
+      // invalid tag, and is cancelled
+      break;
     }
   }
 }
@@ -109,12 +121,10 @@ void etcdv3::AsyncWatchAction::waitForResponse()
 void etcdv3::AsyncWatchAction::CancelWatch()
 {
   if (!isCancelled.exchange(true)) {
-    stream->WritesDone((void*)etcdv3::WATCH_WRITES_DONE);
-
-    grpc::Status status;
-    stream->Finish(&status, (void *)this);
-
-    cq_.Shutdown();
+    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);
   }
 }
 
@@ -133,32 +143,43 @@ void etcdv3::AsyncWatchAction::waitForResponse(std::function<void(etcd::Response
     {
       break;
     }
-    if(isCancelled.load()) {
-      break;
+    if(got_tag == (void *)etcdv3::WATCH_WRITE_CANCEL) {
+      stream->WritesDone((void*)etcdv3::WATCH_WRITES_DONE);
+      continue;
     }
     if(got_tag == (void*)etcdv3::WATCH_WRITES_DONE)
     {
-      isCancelled.store(true);
+      grpc::Status status;
+      stream->Finish(&status, (void *)etcdv3::WATCH_FINISH);
+      continue;
+    }
+    if (got_tag == (void *)etcdv3::WATCH_FINISH) {
+      // shutdown
       cq_.Shutdown();
+      // cancel on-the-fly calls
+      context.TryCancel();
       break;
     }
-    else if(got_tag == (void*)this) // read tag
+    if(got_tag == (void*)this) // read tag
     {
       if (reply.canceled()) {
-        isCancelled.store(true);
-        cq_.Shutdown();
         if (reply.compact_revision() != 0) {
-          auto resp = etcd::Response(grpc::StatusCode::OUT_OF_RANGE /* error code */,
-                                     "required revision has been compacted");
-          resp._compact_revision = reply.compact_revision();
-          callback(resp);
+          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));
         }
-        break;
+        // cancel on-the-fly calls, but don't shutdown the completion queue as there
+        // are still a inflight call to finish
+        context.TryCancel();
+        // cq_.Shutdown();
+        continue;
       }
+
+      // for the callback case, we don't invoke callback immediately if watching
+      // for a future revision, we wait until there are some effective events.
       if(reply.events_size())
       {
-        // for the callback case, we don't stop immediately if watching for a future revison,
-        // we wait until there are some expected events.
         auto resp = ParseResponse();
         auto duration = std::chrono::duration_cast<std::chrono::microseconds>(
             std::chrono::high_resolution_clock::now() - start_timepoint);
@@ -166,6 +187,11 @@ void etcdv3::AsyncWatchAction::waitForResponse(std::function<void(etcd::Response
         start_timepoint = std::chrono::high_resolution_clock::now();
       }
       stream->Read(&reply, (void*)this);
+      continue;
+    }
+    if(isCancelled.load()) {
+      // invalid tag, and is cancelled
+      break;
     }
   }
 }

src/v3/action_constants.cpp

@@ -33,10 +33,13 @@ char const * etcdv3::KEEPALIVE_CREATE = "keepalive create";
 char const * etcdv3::KEEPALIVE_WRITE = "keepalive write";
 char const * etcdv3::KEEPALIVE_READ = "keepalive read";
 char const * etcdv3::KEEPALIVE_DONE = "keepalive done";
+char const * etcdv3::KEEPALIVE_FINISH = "keepalive finish";
 
 char const * etcdv3::WATCH_CREATE = "watch create";
 char const * etcdv3::WATCH_WRITE = "watch write";
+char const * etcdv3::WATCH_WRITE_CANCEL = "watch write cancel";
 char const * etcdv3::WATCH_WRITES_DONE = "watch writes done";
+char const * etcdv3::WATCH_FINISH = "watch finish";
 
 char const * etcdv3::ELECTION_OBSERVE_CREATE = "observe create";
 

tst/AuthTest.cpp

@@ -5,7 +5,7 @@
 
 #include "etcd/Client.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("setup with auth")
 {

tst/CMakeLists.txt

@@ -23,7 +23,15 @@ foreach(testfile ${TEST_FILES})
 
     target_include_directories(${test_name} PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/../proto/gen)
     target_include_directories(${test_name} PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/../proto/gen/proto)
-    target_link_libraries(${test_name} etcd-cpp-api)
+    target_link_libraries(${test_name} PRIVATE etcd-cpp-api)
+
+    if(UNIX AND NOT APPLE)
+        if(CMAKE_VERSION VERSION_LESS 3.13)
+            target_link_libraries(${test_name} PRIVATE -Wl,--no-as-needed -lSegFault -Wl,--as-needed)
+        else()
+            target_link_options(${test_name} PRIVATE -Wl,--no-as-needed -lSegFault -Wl,--as-needed)
+        endif()
+    endif()
 
     add_dependencies(etcd_tests ${test_name})
 endforeach()

tst/CampaignTest.cpp

@@ -0,0 +1,39 @@
+#define CATCH_CONFIG_MAIN
+#include <catch.hpp>
+
+#include <chrono>
+#include <thread>
+
+#include "etcd/Client.hpp"
+#include "etcd/KeepAlive.hpp"
+#include "etcd/Response.hpp"
+#include "etcd/SyncClient.hpp"
+#include "etcd/Value.hpp"
+
+static std::string etcd_uri = etcdv3::detail::resolve_etcd_endpoints(
+	"http://127.0.0.1:2379,http://127.0.0.1:2479,http://127.0.0.1:2579");
+
+TEST_CASE("campaign and loadership using keepalive") {
+  etcd::Client etcd(etcd_uri);
+  auto keepalive = etcd.leasekeepalive(5).get();
+  auto lease_id = keepalive->Lease();
+
+  std::cout << lease_id << std::endl;
+  std::string value = std::string("192.168.1.6:1880");
+  auto resp1 = etcd.campaign("/leader", lease_id, value).get();
+  if (0 == resp1.error_code()) {
+    std::cout << "became leader: " << resp1.index() << std::endl;
+  } else {
+    std::cout << "error code: " << resp1.error_code()
+              << "error message: " << resp1.error_message() << std::endl;
+    assert(false);
+  }
+
+  std::cout << "finish campaign" << std::endl;
+
+  auto resp2 = etcd.leader("/leader").get();
+  std::cout << resp2.value().as_string() << std::endl;
+  std::cout << resp2.value().key() << std::endl;
+
+  std::cout << "finish leader" << std::endl;
+}

tst/ElectionTest.cpp

@@ -8,7 +8,7 @@
 #include "etcd/Client.hpp"
 #include "etcd/KeepAlive.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("setup")
 {

tst/EtcdSyncTest.cpp

@@ -5,7 +5,7 @@
 
 #include "etcd/SyncClient.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("sync operations")
 {

tst/EtcdTest.cpp

@@ -7,7 +7,7 @@
 
 #include "etcd/Client.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("setup")
 {

tst/ForkTest.cpp

@@ -12,7 +12,7 @@
 #include "etcd/Client.hpp"
 #include "etcd/KeepAlive.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("fork: set in child and get from self")
 {

tst/KeepAliveTest.cpp

@@ -10,7 +10,7 @@
 #include "etcd/SyncClient.hpp"
 #include "etcd/Value.hpp"
 
-static std::string etcd_uri(
+static std::string etcd_uri = etcdv3::detail::resolve_etcd_endpoints(
     "http://127.0.0.1:2379,http://127.0.0.1:2479,http://127.0.0.1:2579");
 
 TEST_CASE("keepalive revoke and check if alive") {

tst/LockTest.cpp

@@ -10,7 +10,7 @@
 #include "etcd/Client.hpp"
 #include "etcd/KeepAlive.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("lock and unlock")
 {

tst/MemLeakTest.cpp

@@ -6,7 +6,7 @@
 #include "etcd/Client.hpp"
 #include "etcd/KeepAlive.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 class DistributedLock {
 public:
@@ -75,7 +75,7 @@ DistributedLock::~DistributedLock() noexcept {
 
 int main() {
   int i = 0, t = 0;
-  while(t < 10 /* update this value to make it run for longer */) {
+  while(t < 100 /* update this value to make it run for longer */) {
     {
       DistributedLock lock(std::to_string(i), 0);
       if(!lock.lock_acquired()) {
@@ -88,6 +88,8 @@ int main() {
     if (i == 10) {
       i = 0;
     }
+    if (t % 10 == 0) {
       std::cout << "round: i = " << i << ", t = " << t << std::endl;
     }
+  }
 }

tst/MemLeakWatcherTest.cpp

@@ -0,0 +1,60 @@
+#define CATCH_CONFIG_MAIN
+#include <catch.hpp>
+
+#include <future>
+#include <memory>
+
+#include "etcd/Client.hpp"
+#include "etcd/KeepAlive.hpp"
+#include "etcd/Watcher.hpp"
+
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
+
+static std::atomic_int watcher_called;
+
+void print_response(etcd::Response const & resp)
+{
+  watcher_called.fetch_add(1);
+}
+
+/**
+ * @brief emulate the behavior of creating watcher many times:
+ *
+ * 1. create a watcher
+ * 2. change a value
+ * 3. cancel the watcher
+ */
+void watch_once(etcd::Client & client, std::unique_ptr<etcd::Watcher> &watcher, const size_t round) {
+  const std::string my_prefix = "/test";
+  const std::string my_key = my_prefix + "/foo";
+  watcher.reset(new etcd::Watcher(client, my_prefix, print_response, true));
+
+  int k = watcher_called.load();
+  client.set(my_key, "bar-" + std::to_string(round)).wait();
+  while (true) {
+    if (watcher_called.load() > k) {
+      break;
+    }
+    std::this_thread::sleep_for(std::chrono::milliseconds(1));
+  }
+
+  // cancel the watcher
+  watcher->Cancel();
+}
+
+TEST_CASE("watch shouldn't leak memory")
+{
+  watcher_called.store(0);
+
+  // issue some changes to see if the watcher works
+  etcd::Client client(etcd_url);
+  std::unique_ptr<etcd::Watcher> watcher;
+  for (int round = 0; round < 10 /* update this value to make it run for longer */; ++round) {
+    if (round % 50 == 0) {
+      std::cout << "starting round " << round << std::endl;
+    }
+    watch_once(client, watcher, round);
+  }
+
+  std::cout << "watcher been called for " << watcher_called.load() << " times" << std::endl;
+}

tst/RewatchTest.cpp

@@ -8,7 +8,7 @@
 #include "etcd/SyncClient.hpp"
 #include "etcd/Watcher.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:24799");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 static int watcher_called = 0;
 

tst/SecurityChannelTest.cpp

@@ -9,7 +9,7 @@ static std::string ca = "security-config/certs/ca.crt";
 static std::string cert = "security-config/certs/etcd0.example.com.crt";
 static std::string key = "security-config/private/etcd0.example.com.key";
 
-static const std::string etcd_url("https://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("https://127.0.0.1:2379");
 
 TEST_CASE("setup with auth")
 {

tst/TransactionTest.cpp

@@ -8,7 +8,7 @@
 #include "etcd/Client.hpp"
 #include "etcd/v3/Transaction.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 TEST_CASE("setup")
 {

tst/WatcherTest.cpp

@@ -7,7 +7,7 @@
 #include "etcd/Watcher.hpp"
 #include "etcd/SyncClient.hpp"
 
-static const std::string etcd_url("http://127.0.0.1:2379");
+static const std::string etcd_url = etcdv3::detail::resolve_etcd_endpoints("http://127.0.0.1:2379");
 
 static int watcher_called = 0;