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The API JAR of the XNIO project
/*
* JBoss, Home of Professional Open Source.
* Copyright 2012 Red Hat, Inc., and individual contributors
* as indicated by the @author tags.
*
* 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.xnio.channels;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import org.xnio.ChannelListener;
import org.xnio.ChannelListeners;
import org.xnio.Option;
import org.xnio.XnioExecutor;
import org.xnio.XnioIoThread;
import org.xnio.XnioWorker;
import static org.xnio.Bits.*;
/**
* A bit-bucket stream sink channel. This channel type is always writable.
*
* @author David M. Lloyd
*/
public final class NullStreamSinkChannel implements StreamSinkChannel, WriteListenerSettable, CloseListenerSettable {
private final XnioIoThread thread;
@SuppressWarnings("unused")
private volatile int state;
private ChannelListener writeListener;
private ChannelListener closeListener;
private static final AtomicIntegerFieldUpdater stateUpdater = AtomicIntegerFieldUpdater.newUpdater(NullStreamSinkChannel.class, "state");
private static final int FLAG_ENTERED = 1 << 0;
private static final int FLAG_CLOSED = 1 << 1;
private static final int FLAG_RESUMED = 1 << 2;
/**
* Construct a new instance.
*
* @param thread the write thread for this channel
*/
public NullStreamSinkChannel(final XnioIoThread thread) {
this.thread = thread;
}
public XnioWorker getWorker() {
return thread.getWorker();
}
public XnioIoThread getIoThread() {
return thread;
}
@Deprecated
public XnioExecutor getWriteThread() {
return thread;
}
public long transferFrom(final FileChannel src, final long position, final long count) throws IOException {
int val = enterWrite();
try {
return Math.min(src.size() - position, count);
} finally {
exitWrite(val);
}
}
public long transferFrom(final StreamSourceChannel source, final long count, final ByteBuffer throughBuffer) throws IOException {
int val = enterWrite();
try {
return Channels.drain(source, count);
} finally {
throughBuffer.limit(0);
exitWrite(val);
}
}
public void setWriteListener(final ChannelListener writeListener) {
this.writeListener = writeListener;
}
public ChannelListener getWriteListener() {
return writeListener;
}
public void setCloseListener(final ChannelListener closeListener) {
this.closeListener = closeListener;
}
public ChannelListener getCloseListener() {
return closeListener;
}
public ChannelListener.Setter getWriteSetter() {
return new WriteListenerSettable.Setter(this);
}
public ChannelListener.Setter getCloseSetter() {
return new CloseListenerSettable.Setter(this) ;
}
@Override
public int writeFinal(ByteBuffer src) throws IOException {
return Channels.writeFinalBasic(this, src);
}
@Override
public long writeFinal(ByteBuffer[] srcs, int offset, int length) throws IOException {
return Channels.writeFinalBasic(this, srcs, offset, length);
}
@Override
public long writeFinal(ByteBuffer[] srcs) throws IOException {
return Channels.writeFinalBasic(this, srcs, 0, srcs.length);
}
public int write(final ByteBuffer src) throws IOException {
int val = enterWrite();
try {
return src.remaining();
} finally {
src.position(src.limit());
exitWrite(val);
}
}
public long write(final ByteBuffer[] srcs) throws IOException {
return write(srcs, 0, srcs.length);
}
public long write(final ByteBuffer[] srcs, final int offset, final int length) throws IOException {
if (length == 0) {
return 0L;
}
int val = enterWrite();
try {
long t = 0L;
ByteBuffer src;
for (int i = 0; i < length; i ++) {
src = srcs[i];
t += src.remaining();
src.position(src.limit());
}
return t;
} finally {
exitWrite(val);
}
}
public void suspendWrites() {
int oldVal, newVal;
do {
oldVal = state;
if (allAreClear(oldVal, FLAG_RESUMED) || allAreSet(oldVal, FLAG_CLOSED)) {
return;
}
newVal = oldVal & ~FLAG_RESUMED;
} while (! stateUpdater.compareAndSet(this, oldVal, newVal));
}
public void resumeWrites() {
int oldVal, newVal;
do {
oldVal = state;
if (anyAreSet(oldVal, FLAG_RESUMED | FLAG_CLOSED)) {
return;
}
newVal = oldVal | FLAG_RESUMED;
} while (! stateUpdater.compareAndSet(this, oldVal, newVal));
thread.execute(ChannelListeners.getChannelListenerTask(this, writeListener));
}
public void wakeupWrites() {
resumeWrites();
}
public boolean isWriteResumed() {
final int state = this.state;
return allAreSet(state, FLAG_RESUMED) && allAreClear(state, FLAG_CLOSED);
}
public void shutdownWrites() throws IOException {
int oldVal, newVal;
do {
oldVal = state;
if (allAreSet(oldVal, FLAG_CLOSED)) {
return;
}
newVal = oldVal | FLAG_CLOSED;
} while (! stateUpdater.compareAndSet(this, oldVal, newVal));
writeListener = null;
ChannelListeners.invokeChannelListener(this, closeListener);
}
public void awaitWritable() throws IOException {
// always writable
}
public void awaitWritable(final long time, final TimeUnit timeUnit) throws IOException {
// always writable
}
public boolean flush() throws IOException {
return true;
}
public boolean isOpen() {
return allAreClear(state, FLAG_CLOSED);
}
public void close() throws IOException {
shutdownWrites();
}
public boolean supportsOption(final Option option) {
return false;
}
public T getOption(final Option option) throws IOException {
return null;
}
public T setOption(final Option option, final T value) throws IllegalArgumentException, IOException {
return null;
}
private int enterWrite() throws ClosedChannelException {
int oldVal, newVal;
do {
oldVal = state;
if (allAreSet(oldVal, FLAG_ENTERED)) {
throw new ConcurrentStreamChannelAccessException();
}
if (allAreSet(oldVal, FLAG_CLOSED)) {
throw new ClosedChannelException();
}
newVal = oldVal | FLAG_ENTERED;
} while (! stateUpdater.compareAndSet(this, oldVal, newVal));
return newVal;
}
private void exitWrite(int oldVal) {
int newVal = oldVal & ~FLAG_ENTERED;
while (! stateUpdater.compareAndSet(this, oldVal, newVal)) {
oldVal = state;
newVal = oldVal & ~FLAG_ENTERED;
}
}
}