dbms: Server: queries with several replicas: development [#METR-14410]

dbms/include/DB/Client/ReplicasConnections.h

@@ -36,6 +36,14 @@ namespace DB
 		void sendQuery(const String & query, const String & query_id = "", UInt64 stage = QueryProcessingStage::Complete,
 					   const Settings * settings_ = nullptr, bool with_pending_data = false);
 
+		void disconnect();
+
+		void sendCancel();
+
+		void drainResidualPackets();
+
+		std::string dumpAddresses() const;
+
 	private:
 		using ConnectionHash = std::unordered_map<int, ConnectionInfo>;
 

dbms/include/DB/DataStreams/RemoteBlockInputStream.h

@@ -85,10 +85,20 @@ public:
 
 		if (sent_query && !was_cancelled && !finished && !got_exception_from_server)
 		{
-			LOG_TRACE(log, "(" + connection->getServerAddress() + ") Cancelling query");
+			std::string addresses;
+			if (use_many_replicas)
+				addresses = replicas_connections->dumpAddresses();
+			else
+				addresses = connection->getServerAddress();
+
+			LOG_TRACE(log, "(" + addresses + ") Cancelling query");
 
 			/// Если запрошено прервать запрос - попросим удалённый сервер тоже прервать запрос.
-			connection->sendCancel();
+			if (use_many_replicas)
+				replicas_connections->sendCancel();
+			else
+				connection->sendCancel();
+
 			was_cancelled = true;
 		}
 	}
@@ -100,7 +110,12 @@ public:
 		  *  чтобы оно не осталось висеть в рассихронизированном состоянии.
 		  */
 		if (sent_query && !finished)
-			connection->disconnect();
+		{
+			if (use_many_replicas)
+				replicas_connections->disconnect();
+			else
+				connection->disconnect();
+		}
 	}
 
 protected:
@@ -167,11 +182,27 @@ protected:
 
 				case Protocol::Server::Exception:
 					got_exception_from_server = true;
+
+					if (use_many_replicas)
+					{
+						// Cancel and drain all the remaining connections.
+						replicas_connections->sendCancel();
+						replicas_connections->drainResidualPackets();
+					}
+
 					packet.exception->rethrow();
 					break;
 
 				case Protocol::Server::EndOfStream:
 					finished = true;
+
+					if (use_many_replicas)
+					{
+						// Cancel and drain all the remaining connections.
+						replicas_connections->sendCancel();
+						replicas_connections->drainResidualPackets();
+					}
+
 					return Block();
 
 				case Protocol::Server::Progress:
@@ -224,36 +255,51 @@ protected:
 		/// Отправим просьбу прервать выполнение запроса, если ещё не отправляли.
 		if (!was_cancelled)
 		{
-			LOG_TRACE(log, "(" + connection->getServerAddress() + ") Cancelling query because enough data has been read");
+			std::string addresses;
+			if (use_many_replicas)
+				addresses = replicas_connections->dumpAddresses();
+			else
+				addresses = connection->getServerAddress();
+
+			LOG_TRACE(log, "(" + addresses + ") Cancelling query because enough data has been read");
 
 			was_cancelled = true;
-			connection->sendCancel();
+
+			if (use_many_replicas)
+				replicas_connections->sendCancel();
+			else
+				connection->sendCancel();
 		}
 
-		/// Получим оставшиеся пакеты, чтобы не было рассинхронизации в соединении с сервером.
+		if (use_many_replicas)
-		while (true)
+			replicas_connections->drainResidualPackets();
+		else
 		{
-			Connection::Packet packet = connection->receivePacket();
+			/// Получим оставшиеся пакеты, чтобы не было рассинхронизации в соединении с сервером.
-
+			while (true)
-			switch (packet.type)
 			{
-				case Protocol::Server::Data:
+				Connection::Packet packet = connection->receivePacket();
-				case Protocol::Server::Progress:
-				case Protocol::Server::ProfileInfo:
-				case Protocol::Server::Totals:
-				case Protocol::Server::Extremes:
-					break;
 
-				case Protocol::Server::EndOfStream:
+				switch (packet.type)
-					return;
+				{
+					case Protocol::Server::Data:
+					case Protocol::Server::Progress:
+					case Protocol::Server::ProfileInfo:
+					case Protocol::Server::Totals:
+					case Protocol::Server::Extremes:
+						break;
 
-				case Protocol::Server::Exception:
+					case Protocol::Server::EndOfStream:
-					got_exception_from_server = true;
+						return;
-					packet.exception->rethrow();
-					break;
 
-				default:
+					case Protocol::Server::Exception:
-					throw Exception("Unknown packet from server", ErrorCodes::UNKNOWN_PACKET_FROM_SERVER);
+						got_exception_from_server = true;
+						packet.exception->rethrow();
+						break;
+
+					default:
+						throw Exception("Unknown packet from server", ErrorCodes::UNKNOWN_PACKET_FROM_SERVER);
+				}
 			}
 		}
 

dbms/src/Client/ReplicasConnections.cpp

@@ -83,13 +83,6 @@ namespace DB
 			{
 				Connection::Packet packet = info.connection->receivePacket();
 
-				if (info.packet_number == next_packet_number)
-				{
-					++info.packet_number;
-					++next_packet_number;
-					return packet;
-				}
-
 				switch (packet.type)
 				{
 					case Protocol::Server::Data:
@@ -97,8 +90,6 @@ namespace DB
 					case Protocol::Server::ProfileInfo:
 					case Protocol::Server::Totals:
 					case Protocol::Server::Extremes:
-					case Protocol::Server::Exception:
-						++info.packet_number;
 						break;
 
 					default:
@@ -106,6 +97,15 @@ namespace DB
 						--valid_connections_count;
 						break;
 				}
+
+				if (info.packet_number == next_packet_number)
+				{
+					++info.packet_number;
+					++next_packet_number;
+					return packet;
+				}
+				else
+					++info.packet_number;
 			}
 		}
 	}
@@ -119,4 +119,102 @@ namespace DB
 			connection->sendQuery(query, query_id, stage, settings_, with_pending_data);
 		}
 	}
+
+	void ReplicasConnections::disconnect()
+	{
+		for (auto & e : connection_hash)
+		{
+			ConnectionInfo & info = e.second;
+			if (info.is_valid)
+			{
+				Connection * connection = info.connection;
+				connection->disconnect();
+			}
+		}
+	}
+
+	void ReplicasConnections::sendCancel()
+	{
+		for (auto & e : connection_hash)
+		{
+			ConnectionInfo & info = e.second;
+			if (info.is_valid)
+			{
+				Connection * connection = info.connection;
+				connection->sendCancel();
+			}
+		}
+	}
+
+	void ReplicasConnections::drainResidualPackets()
+	{
+		bool caught_exceptions = false;
+
+		for (auto & e : connection_hash)
+		{
+			ConnectionInfo & info = e.second;
+			if (info.is_valid)
+			{
+				Connection * connection = info.connection;
+				bool again = true;
+
+				while (again)
+				{
+					Connection::Packet packet = connection->receivePacket();
+
+					switch (packet.type)
+					{
+						case Protocol::Server::Data:
+						case Protocol::Server::Progress:
+						case Protocol::Server::ProfileInfo:
+						case Protocol::Server::Totals:
+						case Protocol::Server::Extremes:
+							break;
+
+						case Protocol::Server::EndOfStream:
+							again = false;
+							continue;
+
+						case Protocol::Server::Exception:
+							// Accumulate info from packet.exception
+							caught_exceptions = true;
+							again = false;
+							continue;
+
+						default:
+							// Accumulate info (server address)
+							caught_exceptions = true;
+							again = false;
+							continue;
+					}
+				}
+			}
+		}
+
+		if (caught_exceptions)
+		{
+		}
+	}
+
+	std::string ReplicasConnections::dumpAddresses() const
+	{
+		if (valid_connections_count == 0)
+			return "";
+
+		std::ostringstream os;
+		for (auto & e : connection_hash)
+		{
+			char prefix = '\0';
+			const ConnectionInfo & info = e.second;
+			if (info.is_valid)
+			{
+				const Connection * connection = info.connection;
+				os << prefix << connection->getServerAddress();
+				if (prefix == '\0')
+					prefix = ';';
+			}
+		}
+
+		return os.str();
+	}
 }