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从一个简单的服务器Hander分析Xsocket的启动，首先定义一个简单的EchoHandler继承IDataHandler
public class EchoHandler implements IDataHandler{ public boolean onData(INonBlockingConnection nbc) throws IOException, BufferUnderflowException, MaxReadSizeExceededException { String data = nbc.readStringByDelimiter("\r\n"); nbc.write(data + "\r\n"); return true; } }
然后利用这个IDataHandler启动服务器
public class XsocketTest { public static void main(String[] args) throws UnknownHostException, IOException { // TODO Auto-generated method stub IServer srv = new Server(8090, new EchoHandler()); // run it within the current thread. srv.run(); // the call will not return // ... or start it by using a dedicated thread //srv.start(); // returns after the server has been started } }
这样就实现了一个将客户端发送的字符串回发给客户端的服务器，接口还是很简单的。
从Server的构造开始看起，Server继承自IServer，类描述是接收新的连接，将INonBlockingConnection的处理代理给 分配给Server的 Handler。Server包含Dispatcher，Dispatcher负责执行IO操作，每个Connection都会被分配给一个Dispatcher。为了处理应用相关的事件如onData、onConnected等，Server的Handler的相应的回调函数会被调用。在Server启动阶段，Handler支持的回调函数会通过反射进行解析，回调函数是通过实现不同的接口如IConnectHandler、IDataHandler等进行标记的。通常一个服务器Handler会实现多个Handler接口。这段描述基本介绍了XSocket的整体结构，主要的概念都讲到了，后面还会具体分析。
Server重载了多个构造函数，上面那种构造方式调用了
protected Server(InetSocketAddress address, Map<String, Object> options, IHandler handler, SSLContext sslContext, boolean sslOn, int backlog, int minPoolsize, int maxPoolsize, int taskqueueSize) throws UnknownHostException, IOException { defaultWorkerPool = new WorkerPool(minPoolsize, maxPoolsize, taskqueueSize); workerpool = defaultWorkerPool; if (sslContext != null) { acceptor = ConnectionUtils.getIoProvider().createAcceptor(new LifeCycleHandler(), address, backlog, options, sslContext, sslOn); } else { acceptor = ConnectionUtils.getIoProvider().createAcceptor(new LifeCycleHandler(), address, backlog, options); } localHostname = acceptor.getLocalAddress().getHostName(); localPort = acceptor.getLocalPort(); setHandler(handler); }
主要参数是端口，Ihandler，是否支持ssl，工作线程池参数，除了我们赋予的其他都是默认值。首先创建工作线程池WorkPool，WorkerPool继承自ThreadPoolExecutor，WorkPool构造函数需要一个在任务执行之前存放任务的队列，这里是WorkerPoolAwareQueue extends LinkedBlockingQueue<Runnable>，这个WorkerPoolAwareQueue重写了offer函数加入了日志，并在线程池没有空闲线程且没有达到最大线程数时返回false来强制启动一个新的工作线程而不是放到任务队列中等待，算是一个小的优化。
然后是创建Acceptor。这里创建了一个LifeCycleHandler（重要，后面还会讲），实现了IIoAcceptorCallback接口，接口里定义了onCoonected()等方法在Acceptor绑定到socket或者接收到请求时回调。ConnectionUtils提供了一些集合、ByteBuffer操作的便捷方法，其中的静态变量IoProvider定义了Socket IO的各种参数，createAcceptor函数调用
IoAcceptor acceptor = new IoAcceptor(callback, address, backlog, isReuseAddress);
IoAcceptor构造函数如下
public IoAcceptor(IIoAcceptorCallback callback, InetSocketAddress address, int backlog, SSLContext sslContext, boolean sslOn, boolean isReuseAddress) throws IOException { this.callback = callback; //这个callback就是刚刚说的LifeCycleHandler this.sslContext = sslContext; this.sslOn = sslOn; LOG.fine("try to bind server on " + address); // create a new server socket serverChannel = ServerSocketChannel.open();//构造serverChannel assert (serverChannel != null); serverChannel.configureBlocking(true); serverChannel.socket().setSoTimeout(0); // accept method never times out serverChannel.socket().setReuseAddress(isReuseAddress); //在channel关闭但还存活时是否能够重用端口 try { serverChannel.socket().bind(address, backlog); //构建IoSocketDispatcherPool dispatcherPool = new IoSocketDispatcherPool("Srv" + getLocalPort(), IoProvider.getServerDispatcherInitialSize()); } catch (BindException be) { serverChannel.close(); LOG.warning("could not bind server to " + address + ". Reason: " + DataConverter.toString(be)); throw be; } }
在构造函数中创建了IoSocketDispatcherPool，同时在构建该Pool时实例化了两个IoSocketDispatcher并运行
for (int i = currentRunning; i < size; i++) { IoUnsynchronizedMemoryManager memoryManager = null; if (preallocation) {
//内存管理，采用预分配内存的方法先不管 memoryManager = IoUnsynchronizedMemoryManager.createPreallocatedMemoryManager(preallocationSize, bufferMinsize, useDirect); } else {memoryManager = IoUnsynchronizedMemoryManager.createNonPreallocatedMemoryManager(useDirect); } IoSocketDispatcher dispatcher = new IoSocketDispatcher(memoryManager, name + "#" + i); dispatchers.addLast(dispatcher); Thread t = new Thread(dispatcher); t.setDaemon(true); t.start(); for (IIoDispatcherPoolListener listener : listeners) { listener.onDispatcherAdded(dispatcher); } }
IoSocketDispatcher构造函数调用了selector = Selector.open(); run方法如下
public void run() { // set thread name and attach dispatcher id to thread Thread.currentThread().setName(name); THREADBOUND_ID.set(id); DIRECT_CALL_COUNTER.set(0); if (LOG.isLoggable(Level.FINE)) { LOG.fine("selector " + name + " listening ..."); } int handledTasks = 0; while(isOpen.get()) { try { int eventCount = selector.select(5000); handledTasks = performRegisterHandlerTasks(); //处理注册任务，重要 handledTasks += performKeyUpdateTasks(); //处理key更新任务，重要 if (eventCount > 0) { handleReadWriteKeys(); //处理读写事件，重要 } handledTasks += performDeregisterHandlerTasks(); checkForLooping(eventCount + handledTasks, lastTimeWokeUp); } catch (Throwable e) { // eat and log exception if (LOG.isLoggable(Level.FINE)) { LOG.fine("[" + Thread.currentThread().getName() + "] exception occured while processing. Reason " + DataConverter.toString(e)); } } } for (IoSocketHandler socketHandler : getRegistered()) { socketHandler.onDeregisteredEvent(); } try { selector.close(); } catch (Exception e) { // eat and log exception if (LOG.isLoggable(Level.FINE)) { LOG.fine("error occured by close selector within tearDown " + DataConverter.toString(e)); } } }
再回到最初的main方法，其中调用了srv.run(); run函数最后调用了Acceptor的accept函数
private void accept() { while (isOpen.get()) { try { // blocking accept call SocketChannel channel = serverChannel.accept(); // create IoSocketHandler IoSocketDispatcher dispatcher = dispatcherPool.nextDispatcher(); IoChainableHandler ioHandler = ConnectionUtils.getIoProvider().createIoHandler(false, dispatcher, channel, sslContext, sslOn); // notify call back callback.onConnectionAccepted(ioHandler); acceptedConnections++; } catch (Exception e) { // if acceptor is running (<socket>.close() causes that any // thread currently blocked in accept() will throw a SocketException) if (serverChannel.isOpen()) { LOG.warning("error occured while accepting connection: " + DataConverter.toString(e)); } } } }
重要就完成server的启动，主要启动了一个Acceptor线程和两个Dispatcher线程。
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原文地址：http://www.cnblogs.com/coderway/p/4220108.html
