SocketOutputStream.java
/**
* 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.hadoop.net;
import java.io.EOFException;
import java.io.IOException;
import java.io.OutputStream;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.channels.SelectableChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.WritableByteChannel;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.LongWritable;
/**
* This implements an output stream that can have a timeout while writing.
* This sets non-blocking flag on the socket channel.
* So after creating this object , read() on
* {@link Socket#getInputStream()} and write() on
* {@link Socket#getOutputStream()} on the associated socket will throw
* llegalBlockingModeException.
* Please use {@link SocketInputStream} for reading.
*/
@InterfaceAudience.LimitedPrivate({"HDFS", "MapReduce"})
@InterfaceStability.Unstable
public class SocketOutputStream extends OutputStream
implements WritableByteChannel {
private Writer writer;
private static class Writer extends SocketIOWithTimeout {
WritableByteChannel channel;
Writer(WritableByteChannel channel, long timeout) throws IOException {
super((SelectableChannel)channel, timeout);
this.channel = channel;
}
@Override
int performIO(ByteBuffer buf) throws IOException {
return channel.write(buf);
}
}
/**
* Create a new ouput stream with the given timeout. If the timeout
* is zero, it will be treated as infinite timeout. The socket's
* channel will be configured to be non-blocking.
*
* @param channel
* Channel for writing, should also be a {@link SelectableChannel}.
* The channel will be configured to be non-blocking.
* @param timeout timeout in milliseconds. must not be negative.
* @throws IOException raised on errors performing I/O.
*/
public SocketOutputStream(WritableByteChannel channel, long timeout)
throws IOException {
SocketIOWithTimeout.checkChannelValidity(channel);
writer = new Writer(channel, timeout);
}
/**
* Same as SocketOutputStream(socket.getChannel(), timeout):<br><br>
*
* Create a new ouput stream with the given timeout. If the timeout
* is zero, it will be treated as infinite timeout. The socket's
* channel will be configured to be non-blocking.
*
* @see SocketOutputStream#SocketOutputStream(WritableByteChannel, long)
*
* @param socket should have a channel associated with it.
* @param timeout timeout timeout in milliseconds. must not be negative.
* @throws IOException raised on errors performing I/O.
*/
public SocketOutputStream(Socket socket, long timeout)
throws IOException {
this(socket.getChannel(), timeout);
}
@Override
public void write(int b) throws IOException {
/* If we need to, we can optimize this allocation.
* probably no need to optimize or encourage single byte writes.
*/
byte[] buf = new byte[1];
buf[0] = (byte)b;
write(buf, 0, 1);
}
@Override
public void write(byte[] b, int off, int len) throws IOException {
ByteBuffer buf = ByteBuffer.wrap(b, off, len);
while (buf.hasRemaining()) {
try {
if (write(buf) < 0) {
throw new IOException("The stream is closed");
}
} catch (IOException e) {
/* Unlike read, write can not inform user of partial writes.
* So will close this if there was a partial write.
*/
if (buf.capacity() > buf.remaining()) {
writer.close();
}
throw e;
}
}
}
@Override
public synchronized void close() throws IOException {
/* close the channel since Socket.getOuputStream().close()
* closes the socket.
*/
writer.channel.close();
writer.close();
}
/**
* @return Returns underlying channel used by this stream.
* This is useful in certain cases like channel for
* {@link FileChannel#transferTo(long, long, WritableByteChannel)}
*/
public WritableByteChannel getChannel() {
return writer.channel;
}
//WritableByteChannle interface
@Override
public boolean isOpen() {
return writer.isOpen();
}
@Override
public int write(ByteBuffer src) throws IOException {
return writer.doIO(src, SelectionKey.OP_WRITE);
}
/**
* waits for the underlying channel to be ready for writing.
* The timeout specified for this stream applies to this wait.
*
* @throws SocketTimeoutException
* if select on the channel times out.
* @throws IOException
* if any other I/O error occurs.
*/
public void waitForWritable() throws IOException {
writer.waitForIO(SelectionKey.OP_WRITE);
}
/**
* Transfers data from FileChannel using
* {@link FileChannel#transferTo(long, long, WritableByteChannel)}.
* Updates <code>waitForWritableTime</code> and <code>transferToTime</code>
* with the time spent blocked on the network and the time spent transferring
* data from disk to network respectively.
*
* Similar to readFully(), this waits till requested amount of
* data is transfered.
*
* @param fileCh FileChannel to transfer data from.
* @param position position within the channel where the transfer begins
* @param count number of bytes to transfer.
* @param waitForWritableTime nanoseconds spent waiting for the socket
* to become writable
* @param transferToTime nanoseconds spent transferring data
*
* @throws EOFException
* If end of input file is reached before requested number of
* bytes are transfered.
*
* @throws SocketTimeoutException
* If this channel blocks transfer longer than timeout for
* this stream.
*
* @throws IOException Includes any exception thrown by
* {@link FileChannel#transferTo(long, long, WritableByteChannel)}.
*/
public void transferToFully(FileChannel fileCh, long position, int count,
LongWritable waitForWritableTime,
LongWritable transferToTime) throws IOException {
long waitTime = 0;
long transferTime = 0;
while (count > 0) {
/*
* Ideally we should wait after transferTo returns 0. But because of
* a bug in JRE on Linux (http://bugs.sun.com/view_bug.do?bug_id=5103988),
* which throws an exception instead of returning 0, we wait for the
* channel to be writable before writing to it. If you ever see
* IOException with message "Resource temporarily unavailable"
* thrown here, please let us know.
*
* Once we move to JAVA SE 7, wait should be moved to correct place.
*/
long start = System.nanoTime();
waitForWritable();
long wait = System.nanoTime();
int nTransfered = (int) fileCh.transferTo(position, count, getChannel());
if (nTransfered == 0) {
//check if end of file is reached.
if (position >= fileCh.size()) {
throw new EOFException("EOF Reached. file size is " + fileCh.size() +
" and " + count + " more bytes left to be " +
"transfered.");
}
//otherwise assume the socket is full.
//waitForWritable(); // see comment above.
} else if (nTransfered < 0) {
throw new IOException("Unexpected return of " + nTransfered +
" from transferTo()");
} else {
position += nTransfered;
count -= nTransfered;
}
long transfer = System.nanoTime();
waitTime += wait - start;
transferTime += transfer - wait;
}
if (waitForWritableTime != null) {
waitForWritableTime.set(waitTime);
}
if (transferToTime != null) {
transferToTime.set(transferTime);
}
}
/**
* Call
* {@link #transferToFully(FileChannel, long, int, LongWritable, LongWritable)
* }
* with null <code>waitForWritableTime</code> and <code>transferToTime</code>.
*
* @param fileCh input fileCh.
* @param position input position.
* @param count input count.
* @throws IOException raised on errors performing I/O.
*/
public void transferToFully(FileChannel fileCh, long position, int count)
throws IOException {
transferToFully(fileCh, position, count, null, null);
}
public void setTimeout(int timeoutMs) {
writer.setTimeout(timeoutMs);
}
}