init(channel);//进入init方法。 } catch (Throwable t) { if (channel != null) { // channel can be null if newChannel crashed (eg SocketException("too many open files")) channel.unsafe().closeForcibly(); } // as the Channel is not registered yet we need to force the usage of the GlobalEventExecutor return new DefaultChannelPromise(channel, GlobalEventExecutor.INSTANCE).setFailure(t); }
ChannelFuture regFuture = config().group().register(channel); if (regFuture.cause() != null) { if (channel.isRegistered()) { channel.close(); } else { channel.unsafe().closeForcibly(); } }
// If we are here and the promise is not failed, it's one of the following cases: // 1) If we attempted registration from the event loop, the registration has been completed at this point. // i.e. It's safe to attempt bind() or connect() now because the channel has been registered. // 2) If we attempted registration from the other thread, the registration request has been successfully // added to the event loop's task queue for later execution. // i.e. It's safe to attempt bind() or connect() now: // because bind() or connect() will be executed *after* the scheduled registration task is executed // because register(), bind(), and connect() are all bound to the same thread.
ChannelPipeline p = channel.pipeline();//获取channel的对应的管道。
final EventLoopGroup currentChildGroup = childGroup;//MyServer实例程序中的workerGroup final ChannelHandler currentChildHandler = childHandler;//MyServer实例程序中的MyServerInitializer final Entry<ChannelOption<?>, Object>[] currentChildOptions; final Entry<AttributeKey<?>, Object>[] currentChildAttrs; synchronized (childOptions) { currentChildOptions = childOptions.entrySet().toArray(newOptionArray(childOptions.size())); } synchronized (childAttrs) { currentChildAttrs = childAttrs.entrySet().toArray(newAttrArray(childAttrs.size())); }
p.addLast(new ChannelInitializer<Channel>() { //ChannelInitializer /** This method will be called once the {@link Channel} was registered. After the method returns this instance will be removed from the {@link ChannelPipeline} of the {@link Channel}. 当Channel被注册的时候当前方法会被调用，当方法返回的时候当前Channel的实例会被删除从ChannelPipeline当中。 */ public void initChannel(final Channel ch) throws Exception { final ChannelPipeline pipeline = ch.pipeline(); ChannelHandler handler = config.handler();//MyServer实例程序中的LoggingHandler //LoggingHandler详见MyServer实例程序 http://blog.csdn.net/wzq6578702/article/details/77923602 if (handler != null) { pipeline.addLast(handler);//如果ServerBootstrap的handler被设置过，把设置的Handler放到管道当中。 //详见MyServer实例程序 http://blog.csdn.net/wzq6578702/article/details/77923602 }
public class NioServerSocketChannel extends AbstractNioMessageChannel implements io.netty.channel.socket.ServerSocketChannel { private static final SelectorProvider DEFAULT_SELECTOR_PROVIDER = SelectorProvider.provider(); private static ServerSocketChannel newSocket(SelectorProvider provider) { try { /** * Use the {@link SelectorProvider} to open {@link SocketChannel} and so remove condition in * {@link SelectorProvider#provider()} which is called by each ServerSocketChannel.open() otherwise. * * See <a href="https://github.com/netty/netty/issues/2308">#2308</a>. */ return provider.openServerSocketChannel(); } catch (IOException e) { throw new ChannelException( "Failed to open a server socket.", e); } } //SelectorProvider是jdk提供的一个提供Channel的提供者,java.nio.channels.DatagramChannel、java.nio.channels.Pipe // java.nio.channels.Selector、java.nio.channels.ServerSocketChannel等Channel都是通过SelectorProvider.provider() //打开一个通道，但是SelectorProvider.provider()是同步的（有synchronized）,netty为了适应在高并发的其工况下，这样的同步会造成性能 //的损失，因此将SelectorProvider.provider()获得的SelectorProvider做成一个名字是DEFAULT_SELECTOR_PROVIDER 的常量，获得通道的时候 //直接使用[ return provider.openServerSocketChannel();]类似这样的用法返回Channel，不会有同步加锁操作，提高了并发，有兴趣的可以看下 //https://github.com/netty/netty/issues/2308 说明，为什么netty这样写。
/** * Create a new instance * 无参构造器，主要获取ServerSocketChannel */ public NioServerSocketChannel() { this(newSocket(DEFAULT_SELECTOR_PROVIDER)); }
/** * Create a new instance using the given {@link ServerSocketChannel}. * 设置ServerSocketChannel的兴趣事件（初始状态都是SelectionKey.OP_ACCEPT）、ChannelId（唯一的一个编码）、 * 设置ServerSocketChannel为非阻塞、初始化了ServerSocketChannel的pipline。 * * config 对ServerSocketChannelConfig进行了赋值。 */ public NioServerSocketChannel(ServerSocketChannel channel) { super(null, channel, SelectionKey.OP_ACCEPT); config = new NioServerSocketChannelConfig(this, javaChannel().socket()); }