Hadoop源码分析之RPC(Remote Procedure Call Protocol)

理解这个RPC是不是的先去理解哈动态代理 好多invoke，还有Socket网络编程

先来张eclipse下IPC源码图：

先来看看RPC.java，既然是动态代理，自然会想到Invoke()方法了，先来看看RPC中的Invoker中的invoke()方法

private static class Invoker implements InvocationHandler {
    private InetSocketAddress address;
    private UserGroupInformation ticket;
    private Client client;
    private boolean isClosed = false;

    public Invoker(InetSocketAddress address, UserGroupInformation ticket,
                  Configuration conf, SocketFactory factory) {
      this.address = address;
      this.ticket = ticket;
      this.client = CLIENTS.getClient(conf, factory);
    }

    public Object invoke(Object proxy, Method method, Object[] args)
      throws Throwable {
      final boolean logDebug = LOG.isDebugEnabled();
      long startTime = 0;
      if (logDebug) {
        startTime = System.currentTimeMillis();
      }

      ObjectWritable value = (ObjectWritable)
        client.call(new Invocation(method, args), address,
                    method.getDeclaringClass(), ticket);
      if (logDebug) {
        long callTime = System.currentTimeMillis() - startTime;
        LOG.debug("Call: " + method.getName() + " " + callTime);
      }
      return value.get();
    }
   
    /* close the IPC client that's responsible for this invoker's RPCs */
    synchronized private void close() {
      if (!isClosed) {
        isClosed = true;
        CLIENTS.stopClient(client);
      }
    }
  }

可以看出动态代理里的invoke()方法其实是RPC里的invocation对方法名，参数做了封装，可以看invocation类的