tcp conn pool: pass transport failure reason to callbacks

source/common/conn_pool/conn_pool_base.cc

@@ -577,10 +577,6 @@ ActiveClient::ActiveClient(ConnPoolImplBase& parent, uint32_t lifetime_stream_li
 
 ActiveClient::~ActiveClient() { releaseResourcesBase(); }
 
-void ActiveClient::onEvent(Network::ConnectionEvent event) {
-  parent_.onConnectionEvent(*this, "", event);
-}
-
 void ActiveClient::releaseResourcesBase() {
   if (!resources_released_) {
     resources_released_ = true;

source/common/conn_pool/conn_pool_base.h

@@ -38,7 +38,6 @@ class ActiveClient : public LinkedObject<ActiveClient>,
   void releaseResourcesBase();
 
   // Network::ConnectionCallbacks
-  void onEvent(Network::ConnectionEvent event) override;
   void onAboveWriteBufferHighWatermark() override {}
   void onBelowWriteBufferLowWatermark() override {}
 

source/common/tcp/conn_pool.cc

@@ -65,7 +65,7 @@ void ActiveTcpClient::onEvent(Network::ConnectionEvent event) {
   if (event == Network::ConnectionEvent::Connected) {
     connection_->readDisable(true);
   }
-  Envoy::ConnectionPool::ActiveClient::onEvent(event);
+  parent_.onConnectionEvent(*this, connection_->transportFailureReason(), event);
   if (callbacks_) {
     // Do not pass the Connected event to any session which registered during onEvent above.
     // Consumers of connection pool connections assume they are receiving already connected

source/common/tcp/original_conn_pool.cc

@@ -198,7 +198,8 @@ void OriginalConnPoolImpl::onConnectionEvent(ActiveConn& conn, Network::Connecti
         PendingRequestPtr request =
             pending_requests_to_purge.front()->removeFromList(pending_requests_to_purge);
         host_->cluster().stats().upstream_rq_pending_failure_eject_.inc();
-        request->callbacks_.onPoolFailure(reason, "", conn.real_host_description_);
+        request->callbacks_.onPoolFailure(reason, conn.conn_->transportFailureReason(),
+                                          conn.real_host_description_);
       }
     }
 

test/common/conn_pool/conn_pool_base_test.cc

@@ -25,6 +25,9 @@ class TestActiveClient : public ActiveClient {
   bool closingWithIncompleteStream() const override { return false; }
   uint32_t numActiveStreams() const override { return active_streams_; }
   absl::optional<Http::Protocol> protocol() const override { return absl::nullopt; }
+  void onEvent(Network::ConnectionEvent event) override {
+    parent_.onConnectionEvent(*this, "", event);
+  }
 
   uint32_t active_streams_{};
 };

test/common/tcp/conn_pool_test.cc

@@ -61,10 +61,11 @@ struct ConnPoolCallbacks : public Tcp::ConnectionPool::Callbacks {
     pool_ready_.ready();
   }
 
-  void onPoolFailure(ConnectionPool::PoolFailureReason reason, absl::string_view,
+  void onPoolFailure(ConnectionPool::PoolFailureReason reason, absl::string_view failure_reason,
                      Upstream::HostDescriptionConstSharedPtr host) override {
     reason_ = reason;
     host_ = host;
+    failure_reason_string_ = std::string(failure_reason);
     pool_failure_.ready();
   }
 
@@ -73,6 +74,7 @@ struct ConnPoolCallbacks : public Tcp::ConnectionPool::Callbacks {
   ReadyWatcher pool_ready_;
   ConnectionPool::ConnectionDataPtr conn_data_{};
   absl::optional<ConnectionPool::PoolFailureReason> reason_;
+  std::string failure_reason_string_;
   Upstream::HostDescriptionConstSharedPtr host_;
   Ssl::ConnectionInfoConstSharedPtr ssl_;
 };
@@ -321,6 +323,7 @@ class TcpConnPoolImplDestructorTest : public Event::TestUsingSimulatedTime,
 
   void prepareConn() {
     connection_ = new StrictMock<Network::MockClientConnection>();
+    EXPECT_CALL(*connection_, transportFailureReason()).Times(AtLeast(0));
     EXPECT_CALL(*connection_, setBufferLimits(0));
     EXPECT_CALL(*connection_, detectEarlyCloseWhenReadDisabled(false));
     EXPECT_CALL(*connection_, addConnectionCallbacks(_));
@@ -650,10 +653,13 @@ TEST_P(TcpConnPoolImplTest, RemoteConnectFailure) {
   EXPECT_CALL(*conn_pool_->test_conns_[0].connect_timer_, disableTimer());
 
   EXPECT_CALL(*conn_pool_, onConnDestroyedForTest());
+  EXPECT_CALL(*conn_pool_->test_conns_[0].connection_, transportFailureReason())
+      .WillOnce(Return("foo"));
   conn_pool_->test_conns_[0].connection_->raiseEvent(Network::ConnectionEvent::RemoteClose);
   dispatcher_.clearDeferredDeleteList();
 
   EXPECT_EQ(ConnectionPool::PoolFailureReason::RemoteConnectionFailure, callbacks.reason_);
+  EXPECT_EQ("foo", callbacks.failure_reason_string_);
 
   EXPECT_EQ(1U, cluster_->stats_.upstream_cx_connect_fail_.value());
   EXPECT_EQ(1U, cluster_->stats_.upstream_rq_pending_failure_eject_.value());