FlowControlledOutputStream.java

/*
 * Copyright 2011 Ytai Ben-Tsvi. All rights reserved.
 *  
 * 
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 * 
 *    1. Redistributions of source code must retain the above copyright notice, this list of
 *       conditions and the following disclaimer.
 * 
 *    2. Redistributions in binary form must reproduce the above copyright notice, this list
 *       of conditions and the following disclaimer in the documentation and/or other materials
 *       provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ARSHAN POURSOHI OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * The views and conclusions contained in the software and documentation are those of the
 * authors and should not be interpreted as representing official policies, either expressed
 * or implied.
 */
package ioio.lib.impl;

import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;

class FlowControlledOutputStream extends OutputStream {
	interface Sender {
		void send(byte[] data, int size);
	}

	private final Sender sender_;
	private final BlockingQueue<Byte> queue_ = new ArrayBlockingQueue<Byte>(
			Constants.BUFFER_SIZE);
	private final FlushThread thread_ = new FlushThread();
	private final int maxPacket_;
	private final byte[] packet_;

	private int readyToSend_ = 0;
	private boolean closed_ = false;

	public FlowControlledOutputStream(Sender sender, int maxPacket) {
		sender_ = sender;
		maxPacket_ = maxPacket;
		packet_ = new byte[maxPacket];
		thread_.start();
	}

	@Override
	synchronized public void flush() throws IOException {
		try {
			while (!closed_ && !queue_.isEmpty()) {
				wait();
			}
		} catch (InterruptedException e) {
			throw new IOException("Interrupted");
		}
		if (closed_) {
			throw new IOException("Stream has been closed");
		}
	}

	@Override
	synchronized public void write(int oneByte) throws IOException {
		try {
			while (!closed_ && !queue_.offer((byte) oneByte)) {
				wait();
			}
		} catch (InterruptedException e) {
			throw new IOException("Interrupted");
		}
		if (closed_) {
			throw new IOException("Stream has been closed");
		}
		notifyAll();
	}

	synchronized public void readyToSend(int numBytes) {
		readyToSend_ += numBytes;
		notifyAll();
	}

	@Override
	synchronized public void close() {
		if (closed_) {
			return;
		}
		closed_ = true;
		notifyAll();
		thread_.interrupt();
	}

	class FlushThread extends Thread {
		@Override
		public void run() {
			super.run();
			try {
				while (true) {
					int toSend;
					synchronized (FlowControlledOutputStream.this) {
						while (readyToSend_ == 0 || queue_.isEmpty()) {
							FlowControlledOutputStream.this.wait();
						}
						toSend = Math.min(maxPacket_,
								Math.min(readyToSend_, queue_.size()));
						for (int i = 0; i < toSend; ++i) {
							packet_[i] = queue_.remove();
						}
						readyToSend_ -= toSend;
						FlowControlledOutputStream.this.notifyAll();
					}
					sender_.send(packet_, toSend);
				}
			} catch (InterruptedException e) {
			}
		}
	}
}