mina2.0 源码分析--- 基于nio的服务端socket监听过程_mina resetwakeupsocket subselector.poll-优快云博客

本文链接：https://blog.youkuaiyun.com/wkyb608/article/details/5932823

该博客详细分析了MINA2.0服务端如何利用NIO进行单线程轮询机制的Socket监听。从创建Selector、ServerSocketChannel到启动Acceptor，解释了MINA的IoAcceptor、SimpleIoProcessorPool的工作原理，以及Acceptor线程如何处理客户端请求。

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整体来说，mina服务端采用基于nio的单线程，轮询机制。使用selector 获取客户端的链接，并创建sesssion，session通过process来处理io操作。

nio的典型模式如下所示：

Java代码

private NioEchoServer() throws IOException {
Selector roller = Selector.open();
ServerSocketChannel serverChannel = ServerSocketChannel.open(); //
serverChannel.socket().bind(new InetSocketAddress(port));
serverChannel.configureBlocking(false );
serverChannel.register(roller, SelectionKey.OP_ACCEPT);
}
public void start() throws IOException {
int keyAdded = 0 ;
while ((keyAdded = roller.select()) > 0 ) {
Set<SelectionKey> keySets = roller.selectedKeys();
Iterator iter = keySets.iterator();
while (iter.hasNext()) {
SelectionKey key = (SelectionKey) iter.next();
iter.remove();
actionHandler(key);
}
}
}

private NioEchoServer() throws IOException {
       Selector  roller = Selector.open();
        ServerSocketChannel serverChannel = ServerSocketChannel.open();  //
        serverChannel.socket().bind(new InetSocketAddress(port));
        serverChannel.configureBlocking(false);
        serverChannel.register(roller, SelectionKey.OP_ACCEPT);
    }


  public void start() throws IOException {
        int keyAdded = 0;
        while ((keyAdded = roller.select()) > 0) {
            Set<SelectionKey> keySets = roller.selectedKeys();
            Iterator iter = keySets.iterator();
            while (iter.hasNext()) {
                SelectionKey key = (SelectionKey) iter.next();
                iter.remove();
                actionHandler(key);
            }
        }
    }

1 服务端绑定port

2 创建Selector

3 创建SeversocketChannel，面向流的侦听socket 通道。

4 监听客户端的请求，

接下来就通过mina 创建服务端socket Accpeptor 使用单线程并监处理端口和客户端请求，学习一下mina的源码

Java代码

IoAcceptor acceptor = new NioSoketAcceptor (); //根据实现的类，调用不同的构造方法

IoAcceptor  acceptor  =  new  NioSoketAcceptor ();  //根据实现的类，调用不同的构造方法

上面代码，创建一个socket Acceptor ，mina内部实现如下：

super(new DefaultSocketSessionConfig(), NioProcessor.class); //传入具体的ioprocess 的实现类。

最终调用的类和构造方法：

Java代码

AbstractPollingIoAcceptor
protected AbstractPollingIoAcceptor(IoSessionConfig sessionConfig, //模板模式的使用，根据子类传入IoProcessor实现类构造SimpleIoprocessorPool 池
Class<? extends IoProcessor<T>> processorClass) {
this (sessionConfig, null , new SimpleIoProcessorPool<T>(processorClass),
true );
}

AbstractPollingIoAcceptor     
   protected AbstractPollingIoAcceptor(IoSessionConfig sessionConfig,    //模板模式的使用，根据子类传入IoProcessor实现类构造SimpleIoprocessorPool 池
            Class<? extends IoProcessor<T>> processorClass) {
        this(sessionConfig, null, new SimpleIoProcessorPool<T>(processorClass),
                true);
    }

SimpleIoProcessorPool 创建线程池，提供给Iosession ，做具体的io处理工作。

Java代码

public SimpleIoProcessorPool(Class<? extends IoProcessor<T>> processorType) {
this (processorType, null , DEFAULT_SIZE);
}
public SimpleIoProcessorPool(Class<? extends IoProcessor<T>> processorType, Executor executor, int size) { //构造IOprocessorPool 中的IOprocessor ，并指定Executor；
try {
.....................
.....................
//创建一个可根据需要创建新线程的线程池，但是在以前构造的线程可用时将重用它们，并在需要时使用提供的 ThreadFactory 创建新线程
this .executor = executor = Executors.newCachedThreadPool(); //return new ThreadPoolExecutor ;
...............................
for (int i = 0 ; i < pool.length; i ++)
.........................
...........................
//指定Executor .,线程池，提供构造线程。使用构造函数 NioProcess（Executor execytor ）构造processor ，打开selector 。
processor = processorType.getConstructor(ExecutorService.class ).newInstance(executor);
.............................
..................................
pool[i] = processor;
.....................
} catch (NoSuchMethodException e) {

public SimpleIoProcessorPool(Class<? extends IoProcessor<T>> processorType) {

        this(processorType, null, DEFAULT_SIZE);

   }
     public SimpleIoProcessorPool(Class<? extends IoProcessor<T>> processorType, Executor executor, int size) { //构造IOprocessorPool 中的IOprocessor ，并指定Executor；
    try {
          .....................
          .....................   
         //创建一个可根据需要创建新线程的线程池，但是在以前构造的线程可用时将重用它们，并在需要时使用提供的 ThreadFactory 创建新线程
          this.executor = executor = Executors.newCachedThreadPool();   //return  new ThreadPoolExecutor ;
          ...............................
          for (int i = 0; i < pool.length; i ++)
                 .........................
                 ...........................
            //指定Executor .,线程池，提供构造线程。 使用构造函数 NioProcess（Executor execytor ）构造processor ，打开selector 。     
                      processor = processorType.getConstructor(ExecutorService.class).newInstance(executor);
                .............................
                ..................................
                 pool[i] = processor;
                      .....................
                    } catch (NoSuchMethodException e) {

   应用代码中调用acceptor .bind（），完成对特定端口的绑定，开始监听。
    nioScoket bind （）调用 AbstarctIoProcessor .bind() ,调用 AbstractPollingIo.bindInternal()

完成对客户端的监听。

Java代码

public final void bind(Iterable<? extends SocketAddress> localAddresses) throws IOException {
{
.......................
.....................
try {
boundAddresses.addAll(bindInternal(localAddressesCopy)); //模板模式
} catch (IOException e) {
throw e;
} catch (RuntimeException e) {
throw e;
} catch (Throwable e) {
throw new RuntimeIoException(
"Failed to bind to: " + getLocalAddresses(), e);
}
}
...................
....................
}
AbstractPollingIoacceptor ：
protected final Set<SocketAddress> bindInternal( List<? extends SocketAddress> localAddresses) throws Exception {
AcceptorOperationFuture request = new AcceptorOperationFuture( localAddresses);
registerQueue.add(request);
// acceptor 是一个接受用户请求的线程。It's a thread accepting incoming connections from clients.
// executor.execute(new NamePreservingRunnable(acceptor, actualThreadName));
//启动接受用户请求。
startupAcceptor();
wakeup(); //selector.wakeup(); 使尚未返回的第一个选择操作立即返回。
request.awaitUninterruptibly(); ////堵塞直至监听成功
if (request.getException() != null ) {
throw request.getException();
}
Set<SocketAddress> newLocalAddresses = new HashSet<SocketAddress>();
for (H handle:boundHandles.values()) {
newLocalAddresses.add(localAddress(handle));
return newLocalAddresses;
}

public final void bind(Iterable<? extends SocketAddress> localAddresses) throws IOException {
  {
      .......................
            .....................
      try {
                boundAddresses.addAll(bindInternal(localAddressesCopy));  //模板模式
            } catch (IOException e) {
                throw e;
            } catch (RuntimeException e) {
                throw e;
            } catch (Throwable e) {
                throw new RuntimeIoException(
                        "Failed to bind to: " + getLocalAddresses(), e);
            }
        }
                  ...................
        ....................
  }
 
AbstractPollingIoacceptor  ：
  protected final Set<SocketAddress> bindInternal( List<? extends SocketAddress> localAddresses) throws Exception {

        AcceptorOperationFuture request = new AcceptorOperationFuture( localAddresses);

       registerQueue.add(request);


    //   acceptor 是一个接受用户请求的线程。It's a thread accepting incoming connections from clients.
    //  executor.execute(new NamePreservingRunnable(acceptor, actualThreadName));
     //启动接受用户请求。
        startupAcceptor();            

        wakeup();      //selector.wakeup(); 使尚未返回的第一个选择操作立即返回。

        request.awaitUninterruptibly();  ////堵塞直至监听成功 

        if (request.getException() != null) {

             throw request.getException();
        }
        Set<SocketAddress> newLocalAddresses = new HashSet<SocketAddress>();
        
        for (H handle:boundHandles.values()) {
            newLocalAddresses.add(localAddress(handle));   
            return newLocalAddresses;

  }

AbstractPollingIoAcceptor 的bindInternal （。。。）调用 startupAcceptor，执行 acceptor 线程。

使用自己的私有类，private class Acceptor implements Runnable ，来处理接收客户端请求工作

Java代码

private void startupAcceptor() {
// If the acceptor is not ready, clear the queues
// TODO : they should already be clean : do we have to do that ?
if (!selectable) {
registerQueue.clear();
cancelQueue.clear();
}
// start the acceptor if not already started
synchronized (lock) {
if (acceptor == null ) {
acceptor = new Acceptor();
executeWorker(acceptor);
}
}
}

 private void startupAcceptor() {
        // If the acceptor is not ready, clear the queues
        // TODO : they should already be clean : do we have to do that ?
        if (!selectable) {
            registerQueue.clear();
            cancelQueue.clear();
        }

        // start the acceptor if not already started
        synchronized (lock) {
            if (acceptor == null) {
                acceptor = new Acceptor();
                executeWorker(acceptor);
            }
        }
    }

循环处理客户端请求。

acceptor ，work线程代码

Java代码