org.jppf.io.ChannelInputSource Maven / Gradle / Ivy
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/*
* JPPF.
* Copyright (C) 2005-2015 JPPF Team.
* http://www.jppf.org
*
* Licensed 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.jppf.io;
import java.io.*;
import java.nio.ByteBuffer;
import java.nio.channels.ReadableByteChannel;
import org.jppf.serialization.SerializationUtils;
import org.jppf.utils.pooling.DirectBufferPool;
/**
* Input source backed by a {@link java.nio.channels.ReadableByteChannel ReadableByteChannel}.
* @author Laurent Cohen
*/
public class ChannelInputSource implements InputSource {
/**
* The backing ReadableByteChannel.
*/
protected ReadableByteChannel channel = null;
/**
* Initialize this input source with the specified SocketWrapper.
* @param channel the backing SocketWrapper.
*/
public ChannelInputSource(final ReadableByteChannel channel) {
this.channel = channel;
}
/**
* Read data from this input source into an array of bytes.
* @param data the buffer into which to write.
* @param offset the position in the buffer where to start storing the data.
* @param len the size in bytes of the data to read.
* @return the number of bytes actually read, or -1 if end of stream was reached.
* @throws Exception if an IO error occurs.
*/
@Override
public int read(final byte[] data, final int offset, final int len) throws Exception {
ByteBuffer buffer = ByteBuffer.wrap(data, offset, len);
return read(buffer);
}
/**
* Read data from this input source into a byte buffer.
*
* Implementation details:
* We read the data by small chunks of max {@link IO#TEMP_BUFFER_SIZE} bytes wrapped in a direct ByteBuffer, to work around the fact that Sun NIO implementation of SocketChannelImpl.read() attempts
* to allocate a direct buffer of the requested data size (i.e. data.remaining() in our case), if the destination ByteBuffer is not direct.
* This implementation can result in a "OutOfMemoryError: Direct buffer space" when the size of the data to read is too large.
* See Sun Bug ID: 4879883 for details.
* @param data the buffer into which to write.
* @return the number of bytes actually read, or -1 if end of stream was reached.
* @throws Exception if an IO error occurs.
*/
@Override
public int read(final ByteBuffer data) throws Exception {
ByteBuffer tmpBuffer = null;
try {
tmpBuffer = DirectBufferPool.provideBuffer();
int remaining = data.remaining();
int count = 0;
while (count < remaining) {
if (data.remaining() < tmpBuffer.remaining()) tmpBuffer.limit(data.remaining());
int n = channel.read(tmpBuffer);
if (n < 0) throw new EOFException();
else if (n == 0) break;
else {
count += n;
tmpBuffer.flip();
data.put(tmpBuffer);
tmpBuffer.clear();
}
}
return count;
} finally {
if (tmpBuffer != null) {
DirectBufferPool.releaseBuffer(tmpBuffer);
tmpBuffer = null;
}
}
}
/**
* Read an int value from this input source.
* @return the value read, or -1 if an end of file condition was reached.
* @throws Exception if an IO error occurs.
*/
@Override
public int readInt() throws Exception {
return SerializationUtils.readInt(channel);
}
/**
* Skip n bytes of data form this input source.
* @param n the number of bytes to skip.
* @return the number of bytes actually skipped.
* @throws Exception if an IO error occurs.
*/
@Override
public int skip(final int n) throws Exception {
ByteBuffer buf = ByteBuffer.allocate(n);
read(buf);
return buf.position();
}
/**
* This method does nothing.
* @throws IOException if an IO error occurs.
*/
@Override
public void close() throws IOException {
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("ChannelInputSource[channel=").append(channel).append("]");
return sb.toString();
}
}