深入浅出Netty之三 Server请求处理

Server bind之后，就可以对外提供服务了。Netty使用了reactor模式来提升服务的并发处理能力。boss线程负责监听新的连接请求，当有新的连接进来时，将对应的channel指派一个worker线程来处理。Worker线程负责对该Channel的读写操作。

一.Boss线程

1.阻塞Select

Java代码

1. for (;;) {
2. try {
3. // Boss线程专门负责监听新入连接，所以阻塞select
4. selector.select();
5. // 如果有新连接，先把key清掉
6. selector.selectedKeys().clear();
8. // 循环请求队列，处理连接
9. for (;;) {
10. SocketChannel acceptedSocket = channel.socket.accept();
11. if (acceptedSocket == null) {
12. break;
13. }
14. registerAcceptedChannel(acceptedSocket, currentThread);
16. }
17. ......

 for (;;) {                    try {                        // Boss线程专门负责监听新入连接，所以阻塞select                        selector.select();                        // 如果有新连接，先把key清掉                        selector.selectedKeys().clear();                        // 循环请求队列，处理连接                        for (;;) {                            SocketChannel acceptedSocket = channel.socket.accept();                            if (acceptedSocket == null) {                                break;                            }                            registerAcceptedChannel(acceptedSocket, currentThread);                        }......}

2.注册新连接

Java代码

1. private void registerAcceptedChannel(SocketChannel acceptedSocket, Thread currentThread) {
2. ......
3. //根据用户自定义的的PipelineFactory创建pipeline
4. ChannelPipeline pipeline =
5. channel.getConfig().getPipelineFactory().getPipeline();
6. //hash分配worker线程，默认使用递增循环worker数组方式
7. NioWorker worker = nextWorker();
8. //将新的连接注册到worker线程，让worker线程负责后续读写
9. //新的channel是主channel的子channel，而PipelineSink和主channel是同一个
10. worker.register(new NioAcceptedSocketChannel(
11. channel.getFactory(), pipeline, channel,
12. NioServerSocketPipelineSink.this, acceptedSocket,
13. worker, currentThread), null);
14. ......
15. }

    private void registerAcceptedChannel(SocketChannel acceptedSocket, Thread currentThread) {            ......//根据用户自定义的的PipelineFactory创建pipeline                ChannelPipeline pipeline =                    channel.getConfig().getPipelineFactory().getPipeline();//hash分配worker线程，默认使用递增循环worker数组方式                NioWorker worker = nextWorker();//将新的连接注册到worker线程，让worker线程负责后续读写//新的channel是主channel的子channel，而PipelineSink和主channel是同一个                worker.register(new NioAcceptedSocketChannel(                        channel.getFactory(), pipeline, channel,                        NioServerSocketPipelineSink.this, acceptedSocket,                        worker, currentThread), null);            ......        }

Java代码

1. void register(AbstractNioChannel<?> channel, ChannelFuture future) {
3. synchronized (startStopLock) {
4. ......
5. //创建注册通道的任务
6. Runnable registerTask = createRegisterTask(channel, future);
7. //提交任务到阻塞队列
8. boolean offered = registerTaskQueue.offer(registerTask);
9. //唤醒selector
10. if (wakenUp.compareAndSet(false,true)) {
11. selector.wakeup();
12. }
14. }
15. }

void register(AbstractNioChannel<?> channel, ChannelFuture future) {        synchronized (startStopLock) {            ......    //创建注册通道的任务            Runnable registerTask = createRegisterTask(channel, future);    //提交任务到阻塞队列            boolean offered = registerTaskQueue.offer(registerTask);    //唤醒selector            if (wakenUp.compareAndSet(false, true)) {                selector.wakeup();            }        }    }

3.创建注册任务

Java代码

1. protected Runnable createRegisterTask(AbstractNioChannel<?> channel, ChannelFuture future) {
2. boolean server = !(channel instanceof NioClientSocketChannel);
3. return new RegisterTask((NioSocketChannel) channel, future, server);
4. }

 protected Runnable createRegisterTask(AbstractNioChannel<?> channel, ChannelFuture future) {        boolean server = !(channel instanceof NioClientSocketChannel);        return new RegisterTask((NioSocketChannel) channel, future, server);    }

二.worker线程

worker线程负责对应channel的读写操作，一个worker对应一个selector，会同时处理多个channel的读写。

1.主循环

Java代码

1. for (;;) {
2. wakenUp.set(false);
3. ......
4. if (wakenUp.get()) {
5. wakenupFromLoop = true;
6. selector.wakeup();
7. } else {
8. wakenupFromLoop = false;
9. }
11. cancelledKeys = 0;
12. //处理注册通道的任务
13. processRegisterTaskQueue();
14. //处理异步事件，比如writeComplete事件
15. processEventQueue();
16. //处理写数据任务，如果业务线程有异步写的时候，会有WriteTask放入队列
17. processWriteTaskQueue();
18. //处理IO准备好的那些channel
19. processSelectedKeys(selector.selectedKeys());
20. ......
21. }