• Hadoop源码分析11: IPC流程(6)volatile


    1.Server 的 running

    public abstract class Server {

       volatile boolean running =true; // true while server runs

        publicsynchronized void join() throwsInterruptedException {
           while (running){
           wait();
         }
      }

        public synchronized voidstop() {
        running = false;
           if (handlers != null) {
               for (int i= 0; i < handlerCount; i++) {
                  if (handlers[i] != null){
                 handlers[i].interrupt();
               }
           }
        }
       listener.interrupt();
        listener.doStop();
       responder.interrupt();
        notifyAll();
      } 
    }

    public class ServerHandler extends Thread{
     
    @Override
    public void run() {
       Server.SERVER.set(server);
        ByteArrayOutputStreambuf = new ByteArrayOutputStream(
       Server.INITIAL_RESP_BUF_SIZE);
        while(server.running) {
        try {
           final ServerCall call = server.callQueue.take(); 
           ............................
        } catch(InterruptedException e) {
           if (server.running) { // unexpected -- logit
              .............
           }
        } catch (Exception e){
       }
       }
    }
    }

    public class ServerListener extends Thread{

        public void run(){
       Server.SERVER.set(server);
        while(server.running) {
           SelectionKey key = null;
    t       try {
         。。。。。。
                 } 
             }
         }
    }


    public class ServerListenerReader implements Runnable{

     public void run() {
          synchronized (this) {
           while (serverListener.server.running){
             SelectionKey key =null;
        。。。。。。。。。。。。。。

        
          }
     。。。。。
          }catch (InterruptedException e) {
               if(serverListener.server.running) {                  // unexpected -- log it
               }
             } catch (IOException ex){
              }
       }
    }

    public class ServerResponder extendsThread{

      public void run() {
        Server.SERVER.set(server);
         longlastPurgeTime = 0;  
          while (server.running) {
           try {
             waitPending();    // If a channel is beingregistered, wait.
            writeSelector.select(PURGE_INTERVAL);
             Iterator<SelectionKey> iter =writeSelector.selectedKeys().iterator();
          }     
        }
      } 
    }

    2.ServerConnection 的 rpcCount

    public class ServerConnection {
           volatile intrpcCount = 0;

       private voidprocessData(byte[] buf) throws IOException,
        InterruptedException{
           DataInputStream dis = new DataInputStream(newByteArrayInputStream(buf));
           int id = dis.readInt(); // try to read anid

           Writable param =ReflectionUtils.newInstance(server.paramClass,
           server.conf);// read param
           param.readFields(dis);

           ServerCall call = new ServerCall(id, param,this);
           server.callQueue.put(call); // queue the call;maybe blocked here
           rpcCount++; // Increment the rpccount
        }
       }

    public class ServerListener extends Thread{

        private voidcleanupConnections(boolean force) {
           ...............
             if ( c.rpcCount == 0&& currentTime - c.lastContact > server.maxIdleTime ){
                 server.closeConnection(c);
             numNuked++;
             end--;
               c =null; 
          ...............
        }
    }

    public class ServerResponder extends Thread{

        private booleanprocessResponse(LinkedList<ServerCall> responseQueue,
                                   booleaninHandler) throws IOException {
             。。。。。
             if(!call.response.hasRemaining()) {
              call.connection.rpcCount--;
               if(numElements == 1) {    // lastcall fully processes.
                done = true;           // no more data for thischannel.
               } else{
                done = false;          // more calls pending to besent.
               }
              
             } 
             。。。。。
        }
    }

    3. ServerListenerReader的 adding

    public class ServerListenerReader implements Runnable{

        private volatileboolean adding = false;

        public void run(){
          synchronized (this) {
           while (serverListener.server.running) {
             SelectionKey key =null;
             try {
              readSelector.select();
               while(adding) {
                this.wait(1000);
               }  
            .......................     
          }
       }    

        public voidstartAdd() {
         adding = true;
         readSelector.wakeup();
        }


        public synchronized voidfinishAdd() {
         adding = false;
         this.notify();       
        }
    }

    public class ServerListener extends Thread{

        voiddoAccept(SelectionKey key) throws IOException,OutOfMemoryError {
                ServerConnection c = null;
                ServerSocketChannelserverSocketChannel = (ServerSocketChannel) key.channel();
                SocketChannel channel;
                while ((channel =serverSocketChannel.accept()) != null) {
                    channel.configureBlocking(false);
                    channel.socket().setTcpNoDelay(this.server.tcpNoDelay);
                    ServerListenerReader reader =readers[(currentReader + 1) % readers.length];
                    try {
                     reader.startAdd();
                      SelectionKey readKey =reader.registerChannel(channel);
                      c = newServerConnection(readKey,channel,System.currentTimeMillis(),this.server);
                      readKey.attach(c);
                      synchronized(this.server.connectionList) {
                         this.server.connectionList.add(this.server.numConnections,c);
                          this.server.numConnections++;
                      }
                    } finally{
                   reader.finishAdd();
                    }
            }
        }
    }



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  • 原文地址:https://www.cnblogs.com/leeeee/p/7276525.html
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