java.nio.channels.spi.AbstractSelectableChannel#keyFor()源码实例Demo

public boolean
isPaused(
	AbstractSelectableChannel	channel )
{
    SelectionKey key = channel.keyFor( selector );

    if( key != null && key.isValid() ) {
    	
    	return((  key.interestOps() & INTEREST_OP ) == 0 );
    }else{
        try{  
        	register_cancel_list_mon.enter();

        	Boolean b = paused_states.get( channel );

        	return( b != null && b );
        	
      }finally{ 
    	  register_cancel_list_mon.exit();  
      }
    }
}
 

public void pauseSelects( AbstractSelectableChannel channel ) {

      //System.out.println( "pauseSelects: " + channel + " - " + Debug.getCompressedStackTrace() );

      if( channel == null ) {
        return;
      }

      SelectionKey key = channel.keyFor( selector );

      if( key != null && key.isValid() ) {
        key.interestOps( key.interestOps() & ~INTEREST_OP );
      }
      else {  //channel not (yet?) registered
        if( channel.isOpen() ) {  //only bother if channel has not already been closed
          try{  register_cancel_list_mon.enter();

            paused_states.put( channel, Boolean.TRUE);  //ensure the op is paused upon reg select-time reg

          }
          finally{  register_cancel_list_mon.exit();  }
        }
      }
    }
 

public boolean
isRegistered( AbstractSelectableChannel channel ){

  SelectionKey key = channel.keyFor( selector );

     if( key != null ){
    	 return( true );
     }else{
	  	try{
    		register_cancel_list_mon.enter();

    			// ensure that there's only one operation outstanding for a given channel
    			// at any one time (the latest operation requested )

    		return( register_cancel_list.containsKey( channel ));

    	}finally{

    		register_cancel_list_mon.exit();
    	} 
     }
}
 

public void pauseSelects( AbstractSelectableChannel channel ) {
  
  //System.out.println( "pauseSelects: " + channel + " - " + Debug.getCompressedStackTrace() );
  
  if( channel == null ) {
    return;
  }
  
  SelectionKey key = channel.keyFor( selector );
  
  if( key != null && key.isValid() ) {
    key.interestOps( key.interestOps() & ~INTEREST_OP );
  }
  else {  //channel not (yet?) registered
    if( channel.isOpen() ) {  //only bother if channel has not already been closed
      try{  register_cancel_list_mon.enter();
      
        paused_states.put( channel, new Boolean( true ) );  //ensure the op is paused upon reg select-time reg

      }
      finally{  register_cancel_list_mon.exit();  }
    }
  }
}
 

public void resumeSelects( AbstractSelectableChannel channel ) {
  //System.out.println( "resumeSelects: " + channel + " - " + Debug.getCompressedStackTrace() );
  if( channel == null ) {
    Debug.printStackTrace( new Exception( "resumeSelects():: channel == null" ) );
    return;
  }

  SelectionKey key = channel.keyFor( selector );

  if( key != null && key.isValid() ) {
	  	// if we're resuming a non-interested key then reset the metrics

	if (( key.interestOps() & INTEREST_OP ) == 0 ){
 	   RegistrationData data = (RegistrationData)key.attachment();

 	   data.last_select_success_time 	= SystemTime.getCurrentTime();
 	   data.non_progress_count			= 0;
	}
    key.interestOps( key.interestOps() | INTEREST_OP );
  }
  else {  //channel not (yet?) registered
    try{  register_cancel_list_mon.enter();
      paused_states.remove( channel );  //check if the channel's op has been already paused before select-time reg
    }
    finally{  register_cancel_list_mon.exit();  }
  }

  //try{
  //  selector.wakeup();
  //}
  //catch( Throwable t ) {  Debug.out( "selector.wakeup():: caught exception: ", t );   }
}
 

public void resumeSelects( AbstractSelectableChannel channel ) {
  //System.out.println( "resumeSelects: " + channel + " - " + Debug.getCompressedStackTrace() );
  if( channel == null ) {
    Debug.printStackTrace( new Exception( "resumeSelects():: channel == null" ) );
    return;
  }
  
  SelectionKey key = channel.keyFor( selector );
  
  if( key != null && key.isValid() ) {
	  	// if we're resuming a non-interested key then reset the metrics
	  
	if (( key.interestOps() & INTEREST_OP ) == 0 ){
 	   RegistrationData data = (RegistrationData)key.attachment();

 	   data.last_select_success_time 	= SystemTime.getCurrentTime();
 	   data.non_progress_count			= 0;
	}
    key.interestOps( key.interestOps() | INTEREST_OP );
  }
  else {  //channel not (yet?) registered
    try{  register_cancel_list_mon.enter();
      paused_states.remove( channel );  //check if the channel's op has been already paused before select-time reg
    }
    finally{  register_cancel_list_mon.exit();  }
  }
  
  //try{
  //  selector.wakeup();
  //}
  //catch( Throwable t ) {  Debug.out( "selector.wakeup():: caught exception: ", t );   }
}
 

protected void close(AbstractSelectableChannel channel) {
	if (channel == null)
		return;
	try {
		SelectionKey key = channel.keyFor(selector);
		if (key != null)
			key.cancel();
		channel.close();
	} catch (Exception e) {
		ExceptionMonitor.getInstance().exceptionCaught(e);
	}
}