org.apache.activemq.transport.nio.NIOOutputStream Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of activemq-core Show documentation
Show all versions of activemq-core Show documentation
The ActiveMQ Message Broker and Client implementations
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.transport.nio;
import java.io.EOFException;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.channels.WritableByteChannel;
/**
* An optimized buffered outputstream for Tcp
*
* @version $Revision: 1.1.1.1 $
*/
public class NIOOutputStream extends OutputStream {
private static final int BUFFER_SIZE = 8192;
private final WritableByteChannel out;
private final byte[] buffer;
private final ByteBuffer byteBuffer;
private int count;
private boolean closed;
/**
* Constructor
*
* @param out
*/
public NIOOutputStream(WritableByteChannel out) {
this(out, BUFFER_SIZE);
}
/**
* Creates a new buffered output stream to write data to the specified
* underlying output stream with the specified buffer size.
*
* @param out the underlying output stream.
* @param size the buffer size.
* @throws IllegalArgumentException if size <= 0.
*/
public NIOOutputStream(WritableByteChannel out, int size) {
this.out = out;
if (size <= 0) {
throw new IllegalArgumentException("Buffer size <= 0");
}
buffer = new byte[size];
byteBuffer = ByteBuffer.wrap(buffer);
}
/**
* write a byte on to the stream
*
* @param b - byte to write
* @throws IOException
*/
public void write(int b) throws IOException {
checkClosed();
if (availableBufferToWrite() < 1) {
flush();
}
buffer[count++] = (byte)b;
}
/**
* write a byte array to the stream
*
* @param b the byte buffer
* @param off the offset into the buffer
* @param len the length of data to write
* @throws IOException
*/
public void write(byte b[], int off, int len) throws IOException {
checkClosed();
if (availableBufferToWrite() < len) {
flush();
}
if (buffer.length >= len) {
System.arraycopy(b, off, buffer, count, len);
count += len;
} else {
write(ByteBuffer.wrap(b, off, len));
}
}
/**
* flush the data to the output stream This doesn't call flush on the
* underlying outputstream, because Tcp is particularly efficent at doing
* this itself ....
*
* @throws IOException
*/
public void flush() throws IOException {
if (count > 0 && out != null) {
byteBuffer.position(0);
byteBuffer.limit(count);
write(byteBuffer);
count = 0;
}
}
/**
* close this stream
*
* @throws IOException
*/
public void close() throws IOException {
super.close();
closed = true;
}
/**
* Checks that the stream has not been closed
*
* @throws IOException
*/
protected void checkClosed() throws IOException {
if (closed) {
throw new EOFException("Cannot write to the stream any more it has already been closed");
}
}
/**
* @return the amount free space in the buffer
*/
private int availableBufferToWrite() {
return buffer.length - count;
}
protected void write(ByteBuffer data) throws IOException {
int remaining = data.remaining();
int lastRemaining = remaining - 1;
long delay = 1;
while (remaining > 0) {
// We may need to do a little bit of sleeping to avoid a busy loop.
// Slow down if no data was written out..
if (remaining == lastRemaining) {
try {
// Use exponential rollback to increase sleep time.
Thread.sleep(delay);
delay *= 2;
if (delay > 1000) {
delay = 1000;
}
} catch (InterruptedException e) {
throw new InterruptedIOException();
}
} else {
delay = 1;
}
lastRemaining = remaining;
// Since the write is non-blocking, all the data may not have been
// written.
out.write(data);
remaining = data.remaining();
}
}
}