Bolt服务器的核心类是RpcServer，启动的时候调用父类AbstractRemotingServer的startup方法。
com.alipay.remoting.AbstractRemotingServer#startup
@Override
public void startup() throws LifeCycleException {
super.startup();
try {
doInit();
logger.warn("Prepare to start server on port {} ", port);
if (doStart()) {
logger.warn("Server started on port {}", port);
} else {
logger.warn("Failed starting server on port {}", port);
throw new LifeCycleException("Failed starting server on port: " + port);
}
} catch (Throwable t) {
this.shutdown();// do stop to ensure close resources created during doInit()
throw new IllegalStateException("ERROR: Failed to start the Server!", t);
}
}
这里主要做了三件事
-
调用父类的startup()方法设置状态为启动
com.alipay.remoting.AbstractLifeCycle#startup
@Override
public void startup() throws LifeCycleException {
if (isStarted.compareAndSet(false, true)) {
return;
}
throw new LifeCycleException("this component has started");
} -
调用实现类的doInit()进行实际的初始化工作
com.alipay.remoting.rpc.RpcServer#doInit @Override
protected void doInit() {
if (this.addressParser == null) {
this.addressParser = new RpcAddressParser();
}
if (this.switches().isOn(GlobalSwitch.SERVER_MANAGE_CONNECTION_SWITCH)) {
// in server side, do not care the connection service state, so use null instead of global switch
ConnectionSelectStrategy connectionSelectStrategy = new RandomSelectStrategy(null);
this.connectionManager = new DefaultServerConnectionManager(connectionSelectStrategy);
this.connectionManager.startup(); this.connectionEventHandler = new RpcConnectionEventHandler(switches());
this.connectionEventHandler.setConnectionManager(this.connectionManager);
this.connectionEventHandler.setConnectionEventListener(this.connectionEventListener);
} else {
this.connectionEventHandler = new ConnectionEventHandler(switches());
this.connectionEventHandler.setConnectionEventListener(this.connectionEventListener);
}
initRpcRemoting();
this.bootstrap = new ServerBootstrap();
this.bootstrap.group(bossGroup, workerGroup)
.channel(NettyEventLoopUtil.getServerSocketChannelClass())
.option(ChannelOption.SO_BACKLOG, ConfigManager.tcp_so_backlog())
.option(ChannelOption.SO_REUSEADDR, ConfigManager.tcp_so_reuseaddr())
.childOption(ChannelOption.TCP_NODELAY, ConfigManager.tcp_nodelay())
.childOption(ChannelOption.SO_KEEPALIVE, ConfigManager.tcp_so_keepalive()); // set write buffer water mark
initWriteBufferWaterMark(); // init byte buf allocator
if (ConfigManager.netty_buffer_pooled()) {
this.bootstrap.option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
.childOption(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT);
} else {
this.bootstrap.option(ChannelOption.ALLOCATOR, UnpooledByteBufAllocator.DEFAULT)
.childOption(ChannelOption.ALLOCATOR, UnpooledByteBufAllocator.DEFAULT);
} // enable trigger mode for epoll if need
NettyEventLoopUtil.enableTriggeredMode(bootstrap); final boolean idleSwitch = ConfigManager.tcp_idle_switch();
final int idleTime = ConfigManager.tcp_server_idle();
final ChannelHandler serverIdleHandler = new ServerIdleHandler();
final RpcHandler rpcHandler = new RpcHandler(true, this.userProcessors);
this.bootstrap.childHandler(new ChannelInitializer<SocketChannel>() { @Override
protected void initChannel(SocketChannel channel) {
ChannelPipeline pipeline = channel.pipeline();
pipeline.addLast("decoder", codec.newDecoder());
pipeline.addLast("encoder", codec.newEncoder());
if (idleSwitch) {
pipeline.addLast("idleStateHandler", new IdleStateHandler(0, 0, idleTime,
TimeUnit.MILLISECONDS));
pipeline.addLast("serverIdleHandler", serverIdleHandler);
}
pipeline.addLast("connectionEventHandler", connectionEventHandler);
pipeline.addLast("handler", rpcHandler);
createConnection(channel);
} /**
* create connection operation<br>
* <ul>
* <li>If flag manageConnection be true, use {@link DefaultConnectionManager} to add a new connection, meanwhile bind it with the channel.</li>
* <li>If flag manageConnection be false, just create a new connection and bind it with the channel.</li>
* </ul>
*/
private void createConnection(SocketChannel channel) {
Url url = addressParser.parse(RemotingUtil.parseRemoteAddress(channel));
if (switches().isOn(GlobalSwitch.SERVER_MANAGE_CONNECTION_SWITCH)) {
connectionManager.add(new Connection(channel, url), url.getUniqueKey());
} else {
new Connection(channel, url);
}
channel.pipeline().fireUserEventTriggered(ConnectionEventType.CONNECT);
}
});
}这里的代码看似很复杂，其实主要是配置Netty服务器。Netty服务器的可配置选项通过ConfigManager来获取，Netty的业务处理在childHandler里面。
protected void initChannel(SocketChannel channel) {
ChannelPipeline pipeline = channel.pipeline();
pipeline.addLast("decoder", codec.newDecoder());
pipeline.addLast("encoder", codec.newEncoder());
if (idleSwitch) {
pipeline.addLast("idleStateHandler", new IdleStateHandler(0, 0, idleTime,
TimeUnit.MILLISECONDS));
pipeline.addLast("serverIdleHandler", serverIdleHandler);
}
pipeline.addLast("connectionEventHandler", connectionEventHandler);
pipeline.addLast("handler", rpcHandler);
createConnection(channel);
}初始化channel的方法里面有6个channelHandler
decoder 解码器
encoder 编码器
-
idleStateHandler
Netty自带的空闲处理器，用于触发IdleStateEvent。在这里配置了总空闲时间idleTime(默认值是90000)，即idleTime时间内如果通道没有发生读写操作，将出发一个IdleStateEvent事件。
-
serverIdleHandler
配合idleStateHandler使用，用来处理IdleStateEvent。当触发该时间后，关闭客户端连接
@Override
public void userEventTriggered(final ChannelHandlerContext ctx, Object evt) throws Exception {
if (evt instanceof IdleStateEvent) {
try {
logger.warn("Connection idle, close it from server side: {}",
RemotingUtil.parseRemoteAddress(ctx.channel()));
ctx.close();
} catch (Exception e) {
logger.warn("Exception caught when closing connection in ServerIdleHandler.", e);
}
} else {
super.userEventTriggered(ctx, evt);
}
} -
connectionEventHandler
connect事件处理器，类型由枚举类ConnectionEventType定义
public enum ConnectionEventType {
CONNECT, CLOSE, EXCEPTION;
}-
CONNECT
connect事件在RpcServer.createConnection()方法里触发了一次
-
CLOSE
close事件在连接断开时会触发
com.alipay.remoting.ConnectionEventHandler @Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
String remoteAddress = RemotingUtil.parseRemoteAddress(ctx.channel());
infoLog("Connection channel inactive: {}", remoteAddress);
super.channelInactive(ctx);
Attribute attr = ctx.channel().attr(Connection.CONNECTION);
if (null != attr) {
// add reconnect task
if (this.globalSwitch != null
&& this.globalSwitch.isOn(GlobalSwitch.CONN_RECONNECT_SWITCH)) {
Connection conn = (Connection) attr.get();
if (reconnectManager != null) {
reconnectManager.reconnect(conn.getUrl());
}
}
// trigger close connection event
onEvent((Connection) attr.get(), remoteAddress, ConnectionEventType.CLOSE);
}
} -
EXCEPTION
exception异常事件在源代码里面没有触发的地方，应该是预留的。
无论是什么事件，最终都调用onEvent方法，转发给ConnectionEventListener，最终由用户自定义的ConnectionEventProcessor来处理具体逻辑
com.alipay.remoting.ConnectionEventHandler#onEvent private void onEvent(final Connection conn, final String remoteAddress,
final ConnectionEventType type) {
if (this.eventListener != null) {
this.eventExecutor.onEvent(new Runnable() {
@Override
public void run() {
ConnectionEventHandler.this.eventListener.onEvent(type, remoteAddress, conn);
}
});
}
} com.alipay.remoting.ConnectionEventListener#onEvent
public void onEvent(ConnectionEventType type, String remoteAddress, Connection connection) {
List<ConnectionEventProcessor> processorList = this.processors.get(type);
if (processorList != null) {
for (ConnectionEventProcessor processor : processorList) {
processor.onEvent(remoteAddress, connection);
}
}
} -
-
handler
具体业务处理器，注册类为RpcHandler，调用流程图如下
对于客户端请求的处理交给UserProcessor, 可以调用RpcServer类的registerUserProcessor注册自定义的业务。
-
调用dostart启动服务器
com.alipay.remoting.rpc.RpcServer#doStart @Override
protected boolean doStart() throws InterruptedException {
this.channelFuture = this.bootstrap.bind(new InetSocketAddress(ip(), port())).sync();
return this.channelFuture.isSuccess();
}