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/*
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* Copyright (c) 1996, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.rmi.transport.tcp;
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import java.io.*;
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/**
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* MultiplexOutputStream manages sending data over a conection managed
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* by a ConnectionMultiplexer object. Data written is buffered until the
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* internal buffer is full or the flush() method is called, at which
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* point it attempts to push a packet of bytes through to the remote
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* endpoint. This will never push more bytes than the amount already
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* requested by the remote endpoint (to prevent receive buffer from
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* overflowing), so if the write() and flush() methods will block
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* until their operation can complete if enough bytes cannot be
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* pushed immediately.
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*
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* @author Peter Jones
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*/
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final class MultiplexOutputStream extends OutputStream {
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/** object managing multiplexed connection */
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private ConnectionMultiplexer manager;
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/** information about the connection this is the output stream for */
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private MultiplexConnectionInfo info;
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/** output buffer */
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private byte buffer[];
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/** current position to write to in output buffer */
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private int pos = 0;
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/** pending number of bytes requested by remote endpoint */
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private int requested = 0;
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/** true if this connection has been disconnected */
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private boolean disconnected = false;
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/**
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* lock acquired to access shared variables:
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* requested & disconnected
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* WARNING: Any of the methods manager.send*() should not be
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* invoked while this lock is held, since they could potentially
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* block if the underlying connection's transport buffers are
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* full, and the manager may need to acquire this lock to process
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* and consume data coming over the underlying connection.
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*/
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private Object lock = new Object();
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/**
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* Create a new MultiplexOutputStream for the given manager.
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* @param manager object that manages this connection
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* @param info structure for connection this stream writes to
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* @param bufferLength length of output buffer
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*/
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MultiplexOutputStream(
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ConnectionMultiplexer manager,
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MultiplexConnectionInfo info,
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int bufferLength)
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{
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this.manager = manager;
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this.info = info;
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buffer = new byte[bufferLength];
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pos = 0;
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}
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/**
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* Write a byte over connection.
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* @param b byte of data to write
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*/
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public synchronized void write(int b) throws IOException
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{
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while (pos >= buffer.length)
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push();
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buffer[pos ++] = (byte) b;
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}
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/**
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* Write a subarray of bytes over connection.
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* @param b array containing bytes to write
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* @param off offset of beginning of bytes to write
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* @param len number of bytes to write
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*/
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public synchronized void write(byte b[], int off, int len)
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throws IOException
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{
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if (len <= 0)
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return;
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// if enough free space in output buffer, just copy into there
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int freeSpace = buffer.length - pos;
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if (len <= freeSpace) {
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System.arraycopy(b, off, buffer, pos, len);
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pos += len;
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return;
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}
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// else, flush buffer and send rest directly to avoid array copy
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flush();
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int local_requested;
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while (true) {
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synchronized (lock) {
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while ((local_requested = requested) < 1 && !disconnected) {
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try {
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lock.wait();
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} catch (InterruptedException e) {
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}
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}
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if (disconnected)
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throw new IOException("Connection closed");
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}
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if (local_requested < len) {
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manager.sendTransmit(info, b, off, local_requested);
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off += local_requested;
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len -= local_requested;
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synchronized (lock) {
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requested -= local_requested;
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}
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}
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else {
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manager.sendTransmit(info, b, off, len);
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synchronized (lock) {
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requested -= len;
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}
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// len = 0;
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break;
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}
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}
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}
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/**
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* Guarantee that all data written to this stream has been pushed
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* over and made available to the remote endpoint.
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*/
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public synchronized void flush() throws IOException {
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while (pos > 0)
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push();
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}
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/**
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* Close this connection.
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*/
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public void close() throws IOException
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{
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manager.sendClose(info);
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}
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/**
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* Take note of more bytes requested by conection at remote endpoint.
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* @param num number of additional bytes requested
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*/
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void request(int num)
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{
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synchronized (lock) {
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requested += num;
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lock.notifyAll();
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}
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}
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/**
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* Disconnect this stream from all connection activity.
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*/
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void disconnect()
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{
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synchronized (lock) {
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disconnected = true;
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lock.notifyAll();
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}
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}
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/**
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* Push bytes in output buffer to connection at remote endpoint.
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* This method blocks until at least one byte has been pushed across.
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*/
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private void push() throws IOException
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{
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int local_requested;
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synchronized (lock) {
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while ((local_requested = requested) < 1 && !disconnected) {
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try {
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lock.wait();
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} catch (InterruptedException e) {
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}
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}
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if (disconnected)
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throw new IOException("Connection closed");
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}
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if (local_requested < pos) {
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manager.sendTransmit(info, buffer, 0, local_requested);
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System.arraycopy(buffer, local_requested,
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buffer, 0, pos - local_requested);
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pos -= local_requested;
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synchronized (lock) {
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requested -= local_requested;
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}
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}
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else {
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manager.sendTransmit(info, buffer, 0, pos);
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synchronized (lock) {
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requested -= pos;
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}
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pos = 0;
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}
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}
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}
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