版本:1.2.0
Seata主要包括三大組件:TC、TM和RM。TC（Transaction Coordinator）主要負責全局事務的提交和回滾，是seata的關鍵組件。對可用性及性能都有着較高的要求。
seata TC實現源碼Server的各個包：
- coordinator:協調器核心模塊
- event:事件管理模塊
- lock:資源鎖模塊
- metrics: metrics指標模塊
- session:session通信模塊
- storage:事務信息存儲模塊，file和DB
- store:存儲配置模塊
- transaction:事務模塊
Server啓動流程
server啓動的入口是Server.main方法
/**
* The entry point of application.
*
* @param args the input arguments
* @throws IOException the io exception
*/
public static void main(String[] args) throws IOException {
//初始化參數解析器
ParameterParser parameterParser = new ParameterParser(args);
//初始化度量指標metrics
MetricsManager.get().init();
//設置日誌存儲模式 file/Db
System.setProperty(ConfigurationKeys.STORE_MODE, parameterParser.getStoreMode());
//創建nettyserver
RpcServer rpcServer = new RpcServer(WORKING_THREADS);
//server port
rpcServer.setListenPort(parameterParser.getPort());
UUIDGenerator.init(parameterParser.getServerNode());
//sessionholder 初始化
SessionHolder.init(parameterParser.getStoreMode());
//創建默認協調器
DefaultCoordinator coordinator = new DefaultCoordinator(rpcServer);
coordinator.init();
rpcServer.setHandler(coordinator);
// 註冊關閉鉤子
ShutdownHook.getInstance().addDisposable(coordinator);
ShutdownHook.getInstance().addDisposable(rpcServer);
//127.0.0.1 and 0.0.0.0 are not valid here.
if (NetUtil.isValidIp(parameterParser.getHost(), false)) {
XID.setIpAddress(parameterParser.getHost());
} else {
XID.setIpAddress(NetUtil.getLocalIp());
}
XID.setPort(rpcServer.getListenPort());
try {
//啓動
rpcServer.init();
} catch (Throwable e) {
LOGGER.error("rpcServer init error:{}", e.getMessage(), e);
System.exit(-1);
}
System.exit(0);
}
主要流程：
- 1.解析啓動參數
- 2.初始化度量
- 3.初始化netty server
- 4.初始化sessionholder
- 5.初始化默認協調器
- 6.啓動netty server
參數解析
ParameterParser parameterParser = new ParameterParser(args);
public ParameterParser(String[] args) {
this.init(args);
}
private void init(String[] args) {
try {
boolean inContainer = this.isRunningInContainer();
//判斷是否使用了容器Kubernetes/docker
if (inContainer) {
if (LOGGER.isInfoEnabled()) {
LOGGER.info("The server is running in container.");
}
//多配置環境
this.seataEnv = StringUtils.trimToNull(System.getenv(ENV_SYSTEM_KEY));
//host地址
this.host = StringUtils.trimToNull(System.getenv(ENV_SEATA_IP_KEY));
//server節點id
this.serverNode = NumberUtils.toInt(System.getenv(ENV_SERVER_NODE_KEY), SERVER_DEFAULT_NODE);
//端口號
this.port = NumberUtils.toInt(System.getenv(ENV_SEATA_PORT_KEY), SERVER_DEFAULT_PORT);
//存儲模式
this.storeMode = StringUtils.trimToNull(System.getenv(ENV_STORE_MODE_KEY));
} else {
//JCommander 解析參數
JCommander jCommander = JCommander.newBuilder().addObject(this).build();
jCommander.parse(args);
if (help) {
jCommander.setProgramName(PROGRAM_NAME);
jCommander.usage();
System.exit(0);
}
}
if (StringUtils.isNotBlank(seataEnv)) {
System.setProperty(ENV_PROPERTY_KEY, seataEnv);
}
if (StringUtils.isBlank(storeMode)) {
storeMode = ConfigurationFactory.getInstance().getConfig(ConfigurationKeys.STORE_MODE,
SERVER_DEFAULT_STORE_MODE);
}
} catch (ParameterException e) {
printError(e);
}
}
主要解析參數中的存儲模式、環境配置，ip端口。
初始化server
RpcServer rpcServer = new RpcServer(WORKING_THREADS);
構造器初始化父類構造器
public AbstractRpcRemotingServer(final ThreadPoolExecutor messageExecutor, NettyServerConfig nettyServerConfig) {
super(messageExecutor);
//初始化RpcServer
serverBootstrap = new RpcServerBootstrap(nettyServerConfig);
}
根據配置判斷初始化EventLoopGroup
public RpcServerBootstrap(NettyServerConfig nettyServerConfig) {
this.nettyServerConfig = nettyServerConfig;
//根據配置判斷初始化根據配置判斷初始化EventLoopGroup
if (NettyServerConfig.enableEpoll()) {
this.eventLoopGroupBoss = new EpollEventLoopGroup(nettyServerConfig.getBossThreadSize(),
new NamedThreadFactory(nettyServerConfig.getBossThreadPrefix(), nettyServerConfig.getBossThreadSize()));
this.eventLoopGroupWorker = new EpollEventLoopGroup(nettyServerConfig.getServerWorkerThreads(),
new NamedThreadFactory(nettyServerConfig.getWorkerThreadPrefix(),
nettyServerConfig.getServerWorkerThreads()));
} else {
this.eventLoopGroupBoss = new NioEventLoopGroup(nettyServerConfig.getBossThreadSize(),
new NamedThreadFactory(nettyServerConfig.getBossThreadPrefix(), nettyServerConfig.getBossThreadSize()));
this.eventLoopGroupWorker = new NioEventLoopGroup(nettyServerConfig.getServerWorkerThreads(),
new NamedThreadFactory(nettyServerConfig.getWorkerThreadPrefix(),
nettyServerConfig.getServerWorkerThreads()));
}
// 構造設置端口，防止端口爲空
setListenPort(nettyServerConfig.getDefaultListenPort());
}
SessionHolder初始化
SessionHolder.init(parameterParser.getStoreMode());
根據持久化配置file/db,去初始化sessionManager 進行session管理和持久化，主要包括下面四種
ROOT_SESSION_MANAGERroot session managerASYNC_COMMITTING_SESSION_MANAGER異步提交session managerRETRY_COMMITTING_SESSION_MANAGER重試提交session managerRETRY_ROLLBACKING_SESSION_MANAGER重試回滾session manager
public static void init(String mode) throws IOException {
if (StringUtils.isBlank(mode)) {
mode = CONFIG.getConfig(ConfigurationKeys.STORE_MODE);
}
StoreMode storeMode = StoreMode.get(mode);
//DB 方式
if (StoreMode.DB.equals(storeMode)) {
//初始化四種sessionmanager
...
// File 方式
} else if (StoreMode.FILE.equals(storeMode)) {
//初始化四種sessionmanager
...
} else {
throw new IllegalArgumentException("unknown store mode:" + mode);
}
//reload是否需要進行回滾或提交
//處理未完成的事務
reload();
}
TC協調器初始化
DefaultCoordinator coordinator = new DefaultCoordinator(rpcServer);
coordinator.init();
創建默認的TC協調器，並將server與其組合，主要看init方法
public void init() {
retryRollbacking.scheduleAtFixedRate(() -> {
try {
handleRetryRollbacking();
} catch (Exception e) {
LOGGER.info("Exception retry rollbacking ... ", e);
}
}, 0, ROLLBACKING_RETRY_PERIOD, TimeUnit.MILLISECONDS);
retryCommitting.scheduleAtFixedRate(() -> {
try {
handleRetryCommitting();
} catch (Exception e) {
LOGGER.info("Exception retry committing ... ", e);
}
}, 0, COMMITTING_RETRY_PERIOD, TimeUnit.MILLISECONDS);
asyncCommitting.scheduleAtFixedRate(() -> {
try {
handleAsyncCommitting();
} catch (Exception e) {
LOGGER.info("Exception async committing ... ", e);
}
}, 0, ASYNC_COMMITTING_RETRY_PERIOD, TimeUnit.MILLISECONDS);
timeoutCheck.scheduleAtFixedRate(() -> {
try {
timeoutCheck();
} catch (Exception e) {
LOGGER.info("Exception timeout checking ... ", e);
}
}, 0, TIMEOUT_RETRY_PERIOD, TimeUnit.MILLISECONDS);
undoLogDelete.scheduleAtFixedRate(() -> {
try {
undoLogDelete();
} catch (Exception e) {
LOGGER.info("Exception undoLog deleting ... ", e);
}
}, UNDO_LOG_DELAY_DELETE_PERIOD, UNDO_LOG_DELETE_PERIOD, TimeUnit.MILLISECONDS);
}
init方法主要是添加定時任務，處理提交回滾刪除日誌等操作
啓動server
rpcServer.init();
public void init() {
//實例化默認的服務消息監聽器，包括事務消息、RM註冊消息、TM註冊消息、檢查消息
DefaultServerMessageListenerImpl defaultServerMessageListenerImpl =
new DefaultServerMessageListenerImpl(getTransactionMessageHandler());
//初始化日誌處理線程池
defaultServerMessageListenerImpl.init();
defaultServerMessageListenerImpl.setServerMessageSender(this);
super.setServerMessageListener(defaultServerMessageListenerImpl);
//添加channelhandler
super.setChannelHandlers(new ServerHandler());
//核心方法
super.init();
}
進入init方法,AbstractRpcRemotingServer.init()
public void init() {
//啓動超時消息定時任務
super.init();
//啓動服務
serverBootstrap.start();
}
跟入serverBootstrap.start();,這裏就是服務的初始化
public void start() {
//設置channel參數
this.serverBootstrap.group(this.eventLoopGroupBoss, this.eventLoopGroupWorker)
.channel(nettyServerConfig.SERVER_CHANNEL_CLAZZ)
.option(ChannelOption.SO_BACKLOG, nettyServerConfig.getSoBackLogSize())
.option(ChannelOption.SO_REUSEADDR, true)
.childOption(ChannelOption.SO_KEEPALIVE, true)
.childOption(ChannelOption.TCP_NODELAY, true)
.childOption(ChannelOption.SO_SNDBUF, nettyServerConfig.getServerSocketSendBufSize())
.childOption(ChannelOption.SO_RCVBUF, nettyServerConfig.getServerSocketResvBufSize())
.childOption(ChannelOption.WRITE_BUFFER_WATER_MARK,
new WriteBufferWaterMark(nettyServerConfig.getWriteBufferLowWaterMark(),
nettyServerConfig.getWriteBufferHighWaterMark()))
.localAddress(new InetSocketAddress(listenPort))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) {
ch.pipeline().addLast(new IdleStateHandler(nettyServerConfig.getChannelMaxReadIdleSeconds(), 0, 0))
.addLast(new ProtocolV1Decoder())
.addLast(new ProtocolV1Encoder());
if (null != channelHandlers) {
addChannelPipelineLast(ch, channelHandlers);
}
}
});
try {
ChannelFuture future = this.serverBootstrap.bind(listenPort).sync();
LOGGER.info("Server started ... ");
//高可用註冊
RegistryFactory.getInstance().register(new InetSocketAddress(XID.getIpAddress(), XID.getPort()));
initialized.set(true);
future.channel().closeFuture().sync();
} catch (Exception exx) {
throw new RuntimeException(exx);
}
}
主要是netty參數的配置並啓動，到這裏也就完成了SeataServer的初始化及啓動。通過seata-server的源碼看出，其內部使用netty作爲服務器，並且用到大量線程池和定時任務去提高性能。