//******************************************************************************
//
// File:    NetworkChannelSendThread.java
// Package: edu.rit.mp
// Unit:    Class edu.rit.mp.NetworkChannelSendThread
//
// This Java source file is copyright (C) 2008 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.mp;

import java.io.IOException;

import java.nio.ByteBuffer;

import java.nio.channels.SocketChannel;

import java.util.concurrent.LinkedBlockingQueue;

/**
 * Class NetworkChannelSendThread provides a thread for sending outgoing
 * messages for a {@linkplain NetworkChannel}.
 *
 * @author  Alan Kaminsky
 * @version 12-Oct-2008
 */
class NetworkChannelSendThread
	extends Thread
	{

// Hidden data members.

	// Enclosing network channel.
	private NetworkChannel myNetworkChannel;

	// Underlying socket channel.
	private SocketChannel mySocketChannel;

	// Queue of outgoing I/O requests.
	private LinkedBlockingQueue<IORequest> myOutgoingQueue;

	// Byte buffer.
	private ByteBuffer myByteBuffer;

// Hidden constructors.

	/**
	 * Construct a new network channel send thread.
	 *
	 * @param  theNetworkChannel  Enclosing network channel.
	 * @param  theSocketChannel   Underlying socket channel.
	 * @param  theOutgoingQueue   Queue of outgoing I/O requests.
	 */
	NetworkChannelSendThread
		(NetworkChannel theNetworkChannel,
		 SocketChannel theSocketChannel,
		 LinkedBlockingQueue<IORequest> theOutgoingQueue)
		{
		myNetworkChannel = theNetworkChannel;
		mySocketChannel = theSocketChannel;
		myOutgoingQueue = theOutgoingQueue;
		myByteBuffer = ByteBuffer.allocateDirect (Constants.BUFFER_SIZE);
		setDaemon (true);
		start();
		}

// Exported operations.

	/**
	 * Run this network channel send thread.
	 */
	public void run()
		{
		IORequest iorequest = null;
		Buf buf = null;

		// Processing loop.
		sendloop: for (;;)
			{
			try
				{
				// Wait for an I/O request to show up in the outgoing queue.
				iorequest = myOutgoingQueue.take();
				buf = iorequest.myBuf;

				// Message preprocessing.
				buf.preSend();
				myByteBuffer.clear();
				int i = 0;
				int msglength = buf.myMessageLength;

				// Write message header.
				myByteBuffer.putInt (Constants.MAGIC_NUMBER);
				myByteBuffer.putInt (iorequest.myTagLb);
				myByteBuffer.put (buf.myMessageType);
				myByteBuffer.putInt (msglength);

				// Repeatedly transfer items from source buffer to byte buffer,
				// then from byte buffer to socket channel.
				while (i < msglength)
					{
					i += buf.sendItems (i, myByteBuffer);
					myByteBuffer.flip();
					mySocketChannel.write (myByteBuffer);
					myByteBuffer.compact();
					}
				myByteBuffer.flip();
				while (myByteBuffer.hasRemaining())
					{
					mySocketChannel.write (myByteBuffer);
					myByteBuffer.compact();
					myByteBuffer.flip();
					}

				// Message postprocessing.
				buf.postSend();

				// Report success of current I/O request.
				iorequest.reportSuccess();

				iorequest = null;
				buf = null;
				}

			catch (IOException exc)
				{
				// Report failure of current I/O request.
				if (iorequest != null)
					{
					iorequest.reportFailure (exc);
					}
				}

			catch (InterruptedException exc)
				{
				ChannelClosedException exc2 =
					new ChannelClosedException ("Channel closed");

				// Report failure of current I/O request.
				if (iorequest != null)
					{
					iorequest.reportFailure (exc2);
					}

				// Report failure of any pending I/O requests.
				while ((iorequest = myOutgoingQueue.poll()) != null)
					{
					iorequest.reportFailure (exc2);
					}

				// Terminate this thread.
				break sendloop;
				}

			catch (RuntimeException exc)
				{
				// Report failure of current I/O request.
				if (iorequest != null)
					{
					iorequest.reportFailure (exc);
					}
				}

			catch (Error exc)
				{
				// Report failure of current I/O request.
				if (iorequest != null)
					{
					iorequest.reportFailure (exc);
					}
				}
			}

		// This thread is terminating. Enable garbage collection of data
		// members.
		myNetworkChannel = null;
		mySocketChannel = null;
		myOutgoingQueue = null;
		myByteBuffer = null;
		}

	}