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	/*
	* Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/
	package sun.rmi.transport.tcp;

	import java.io.*;

	/**
	* MultiplexOutputStream manages sending data over a connection managed
	* by a ConnectionMultiplexer object. Data written is buffered until the
	* internal buffer is full or the flush() method is called, at which
	* point it attempts to push a packet of bytes through to the remote
	* endpoint. This will never push more bytes than the amount already
	* requested by the remote endpoint (to prevent receive buffer from
	* overflowing), so if the write() and flush() methods will block
	* until their operation can complete if enough bytes cannot be
	* pushed immediately.
	*
	* @author Peter Jones
	*/
	final class MultiplexOutputStream extends OutputStream {

	/** object managing multiplexed connection */
	private ConnectionMultiplexer manager;

	/** information about the connection this is the output stream for */
	private MultiplexConnectionInfo info;

	/** output buffer */
	private byte buffer[];

	/** current position to write to in output buffer */
	private int pos = 0;

	/** pending number of bytes requested by remote endpoint */
	private int requested = 0;

	/** true if this connection has been disconnected */
	private boolean disconnected = false;

	/**
	* lock acquired to access shared variables:
	* requested & disconnected
	* WARNING: Any of the methods manager.send*() should not be
	* invoked while this lock is held, since they could potentially
	* block if the underlying connection's transport buffers are
	* full, and the manager may need to acquire this lock to process
	* and consume data coming over the underlying connection.
	*/
	private Object lock = new Object();

	/**
	* Create a new MultiplexOutputStream for the given manager.
	* @param manager object that manages this connection
	* @param info structure for connection this stream writes to
	* @param bufferLength length of output buffer
	*/
	MultiplexOutputStream(
	ConnectionMultiplexer manager,
	MultiplexConnectionInfo info,
	int bufferLength)
	{
	this.manager = manager;
	this.info = info;

	buffer = new byte[bufferLength];
	pos = 0;
	}

	/**
	* Write a byte over connection.
	* @param b byte of data to write
	*/
	public synchronized void write(int b) throws IOException
	{
	while (pos >= buffer.length)
	push();
	buffer[pos ++] = (byte) b;
	}

	/**
	* Write a subarray of bytes over connection.
	* @param b array containing bytes to write
	* @param off offset of beginning of bytes to write
	* @param len number of bytes to write
	*/
	public synchronized void write(byte b[], int off, int len)
	throws IOException
	{
	if (len <= 0)
	return;

	// if enough free space in output buffer, just copy into there
	int freeSpace = buffer.length - pos;
	if (len <= freeSpace) {
	System.arraycopy(b, off, buffer, pos, len);
	pos += len;
	return;
	}

	// else, flush buffer and send rest directly to avoid array copy
	flush();
	int local_requested;
	while (true) {
	synchronized (lock) {
	while ((local_requested = requested) < 1 && !disconnected) {
	try {
	lock.wait();
	} catch (InterruptedException e) {
	}
	}
	if (disconnected)
	throw new IOException("Connection closed");
	}

	if (local_requested < len) {
	manager.sendTransmit(info, b, off, local_requested);
	off += local_requested;
	len -= local_requested;
	synchronized (lock) {
	requested -= local_requested;
	}
	}
	else {
	manager.sendTransmit(info, b, off, len);
	synchronized (lock) {
	requested -= len;
	}
	// len = 0;
	break;
	}
	}
	}

	/**
	* Guarantee that all data written to this stream has been pushed
	* over and made available to the remote endpoint.
	*/
	public synchronized void flush() throws IOException {
	while (pos > 0)
	push();
	}

	/**
	* Close this connection.
	*/
	public void close() throws IOException
	{
	manager.sendClose(info);
	}

	/**
	* Take note of more bytes requested by connection at remote endpoint.
	* @param num number of additional bytes requested
	*/
	void request(int num)
	{
	synchronized (lock) {
	requested += num;
	lock.notifyAll();
	}
	}

	/**
	* Disconnect this stream from all connection activity.
	*/
	void disconnect()
	{
	synchronized (lock) {
	disconnected = true;
	lock.notifyAll();
	}
	}

	/**
	* Push bytes in output buffer to connection at remote endpoint.
	* This method blocks until at least one byte has been pushed across.
	*/
	private void push() throws IOException
	{
	int local_requested;
	synchronized (lock) {
	while ((local_requested = requested) < 1 && !disconnected) {
	try {
	lock.wait();
	} catch (InterruptedException e) {
	}
	}
	if (disconnected)
	throw new IOException("Connection closed");
	}

	if (local_requested < pos) {
	manager.sendTransmit(info, buffer, 0, local_requested);
	System.arraycopy(buffer, local_requested,
	buffer, 0, pos - local_requested);
	pos -= local_requested;
	synchronized (lock) {
	requested -= local_requested;
	}
	}
	else {
	manager.sendTransmit(info, buffer, 0, pos);
	synchronized (lock) {
	requested -= pos;
	}
	pos = 0;
	}
	}
	}

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