2-1-3.Netty源码:端口绑定

端口绑定

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//AbstractBootstrap.java
 private static void doBind0(
        final ChannelFuture regFuture, final Channel channel,
        final SocketAddress localAddress, final ChannelPromise promise) {

  //把绑定接口的方法做成一个Task 扔到事件执行器 中执行
  channel.eventLoop().execute(new Runnable() {
    @Override
    public void run() {
      if (regFuture.isSuccess()) {
          channel.bind(localAddress, promise).addListener(ChannelFutureListener.CLOSE_ON_FAILURE);
      } else {
          promise.setFailure(regFuture.cause());
      }
    }
  });
}

• 【11】具体实现绑定方法在AbstractChannel#bind()

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   @Override
  public final void bind(final SocketAddress localAddress, final ChannelPromise promise) {
      assertEventLoop();
    
      if (!promise.setUncancellable() || !ensureOpen(promise)) {
          return;
      }
      ...
      //false
      boolean wasActive = isActive();
      try {
          doBind(localAddress);
      } catch (Throwable t) {
        ...
      }
    
      if (!wasActive && isActive()) {
          invokeLater(new Runnable() {
              @Override
              public void run() {
                  pipeline.fireChannelActive();
              }
          });
      }
    
      safeSetSuccess(promise);
  }
  

  • 【12】底层是使用了jdk底层进行绑定
  • 【17】判断是否绑定了isactive方法也是用jdk地层实现的 javaChannel().socket().isBound();

  • 【21】完成绑定后发送事件

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      public void channelActive(ChannelHandlerContext ctx) throws Exception {
          ctx.fireChannelActive();
          readIfIsAutoRead();
      }
    

    • 【2】传播channel激活事件

    • 【3】层层的调用最终实现方式是在AbstractNioChannel#doBeginRead

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      //AbstractNioChannel.java
       protected void doBeginRead() throws Exception {
        final SelectionKey selectionKey = this.selectionKey;
        if (!selectionKey.isValid()) {
            return;
        }
        ...
        
        final int interestOps = selectionKey.interestOps();
        if ((interestOps & readInterestOp) == 0) {
            selectionKey.interestOps(interestOps | readInterestOp);
        }
      }
      

      获取服务端channel注册到selector上的selectionKey，然后获取这个key的interestOps 然后判断这个interestOps是否是0（SelectionKey.OP_ACCEPT，具体请见【1-2-1.Netty源码:服务端NioServerSocketChanne构造方法】）如果等于0 做个或操绑定Accept事件，再重新绑定到selectionKey。

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