channelrequest.java

sea是一个基于seda模式的实现。这个设计模式将系统分为很多stage。每个stage分布不同的任务（基于线程池）。通过任务流的方式提高系统的效率。

/*
 * Copyright (c) 2003, The Regents of the University of California, through
 * Lawrence Berkeley National Laboratory (subject to receipt of any required
 * approvals from the U.S. Dept. of Energy). All rights reserved.
 */
package gov.lbl.dsd.sea.nio.event;

import gov.lbl.dsd.sea.Stage;
import gov.lbl.dsd.sea.event.GenericCallbackEvent;

import java.nio.ByteBuffer;
import java.nio.channels.SelectableChannel;

/**
 * Requests an agent to perform some action on a given channel.
 * 
 * @author [e-mail]
 * @author $Author: hoschek3 $
 * @version $Revision: 1.18 $, $Date: 2004/07/28 19:49:20 $
 */
public abstract class ChannelRequest {

	private ChannelRequest() {} // not instantiable
	
	/**
	 * Requests an agent to register the given
	 * {@link java.nio.channels.SelectionKey}interest ops with the given
	 * channel; The agent will enqueue future responses to the channel onto the
	 * given observer stage; If an attachment is given the agent will attach it to the channel's key.
	 */
	public static class Register extends GenericCallbackEvent {
		
		protected Object attachment;
		
		protected static final Object NO_ATTACHMENT = new Object(); // indicates agent should not modify current attachment

		public Register(Stage observer, SelectableChannel channel, int interestOps) {
			this(observer, channel, interestOps, NO_ATTACHMENT);
		}

		public Register(Stage observer, SelectableChannel channel, int interestOps, Object attachment) {
			super(observer, channel, new Integer(interestOps));
			this.attachment = attachment;
		}

		public int getInterestOps() {
			return ((Integer) this.getInfo()).intValue();
		}

		public SelectableChannel getChannel() {
			return (SelectableChannel) this.getMessage();
		}
		
		/**
		 * Returns the attachment the agent should attach to the channel's key.
		 * 
		 * @throws IllegalStateException if <code>hasAttachment() == false</code>.
		 */
		public Object getAttachment() {
			if (!hasAttachment()) throw new IllegalStateException("no attachment available");
			return this.attachment;
		}		

		/**
		 * Returns whether or not the request contains an attachment.
		 */
		public boolean hasAttachment() {
			return this.attachment != NO_ATTACHMENT;
		}		
	}
		
	/**
	 * Requests an agent to close the given channel.
	 */
	public static class Close extends GenericCallbackEvent {

		public Close(SelectableChannel channel) {
			super(null, channel);
		}

		public SelectableChannel getChannel() {
			return (SelectableChannel) this.getMessage();
		}
	}

	/**
	 * Requests an agent to completely write ALL of the bytes in the given buffer
	 * to the given channel; As usual with NIO, the data is contained between
	 * indexes <code>buffer.position()</code> and <code>buffer.limit()</code>,
	 * and <code>buffer.remaining()</code> bytes will be written; 
	 */
	public static class WriteData extends GenericCallbackEvent {

		public WriteData(SelectableChannel channel, ByteBuffer buffer) {
			super(null, channel, buffer);
		}

		public SelectableChannel getChannel() {
			return (SelectableChannel) this.getMessage();
		}

		public ByteBuffer getBuffer() {
			return (ByteBuffer) this.getInfo();
		}

	}	

//	/**
//	 * Requests an agent to add the given {@link java.nio.channels.SelectionKey}
//	 * interest ops to the ops registered with the given channel; The agent will
//	 * enqueue future responses to the channel onto the given observer stage; If
//	 * an attachment is given the agent will attach it to the channel's key.
//	 */
//	public static class RegisterAdd extends Register {
//		
//		public RegisterAdd(Stage observer, SelectableChannel channel, int interestOps) {
//			this(observer, channel, interestOps, NO_ATTACHMENT);
//		}
//
//		public RegisterAdd(Stage observer, SelectableChannel channel, int interestOps, Object attachment) {
//			super(observer, channel, interestOps);
//			this.attachment = attachment;
//		}
//
//	}
//
//	/**
//	 * Requests an agent to remove the given {@link java.nio.channels.SelectionKey}
//	 * interest ops from the ops registered with the given channel; The agent will
//	 * enqueue future responses to the channel onto the given observer stage; If
//	 * an attachment is given the agent will attach it to the channel's key.
//	 */
//	public static class RegisterRemove extends Register {
//		
//		public RegisterRemove(Stage observer, SelectableChannel channel, int interestOps) {
//			this(observer, channel, interestOps, NO_ATTACHMENT);
//		}
//
//		public RegisterRemove(Stage observer, SelectableChannel channel, int interestOps, Object attachment) {
//			super(observer, channel, interestOps);
//			this.attachment = attachment;
//		}
//
//	}
//
//	/**
//	 * Requests an agent to assign the given {@link java.nio.channels.SelectionKey}
//	 * interest ops to the ops registered with the given channel; The agent will
//	 * enqueue future responses to the channel onto the given observer stage; If
//	 * an attachment is given the agent will attach it to the channel's key.
//	 */
//	public static class RegisterSet extends Register {
//		
//		public RegisterSet(Stage observer, SelectableChannel channel, int interestOps) {
//			this(observer, channel, interestOps, NO_ATTACHMENT);
//		}
//
//		public RegisterSet(Stage observer, SelectableChannel channel, int interestOps, Object attachment) {
//			super(observer, channel, interestOps);
//			this.attachment = attachment;
//		}
//
//	}
}