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* JBoss, Home of Professional Open Source.
* Copyright 2014 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 io.undertow.channels;
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 org.xnio.channels.StreamSinkChannel;
import org.xnio.channels.StreamSourceChannel;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.util.concurrent.TimeUnit;
import static org.xnio.Bits.allAreClear;
import static org.xnio.Bits.allAreSet;
import static org.xnio.Bits.anyAreClear;
import static org.xnio.Bits.anyAreSet;
/**
* A 'gated' stream sink channel.
*
* This channel has a gate which starts of closed. When the gate is closed writes will return 0. When the gate is opened
* writes will resume as normal.
*
* @author David M. Lloyd
*/
public final class GatedStreamSinkChannel implements StreamSinkChannel {
private final StreamSinkChannel delegate;
private final ChannelListener.SimpleSetter writeSetter = new ChannelListener.SimpleSetter<>();
private final ChannelListener.SimpleSetter closeSetter = new ChannelListener.SimpleSetter<>();
/**
* Construct a new instance.
*
* @param delegate the channel to wrap
*/
public GatedStreamSinkChannel(final StreamSinkChannel delegate) {
this.delegate = delegate;
}
@SuppressWarnings("unused")
private int state;
private static final int FLAG_GATE_OPEN = 1 << 0;
private static final int FLAG_WRITES_RESUMED = 1 << 1;
private static final int FLAG_CLOSE_REQUESTED = 1 << 2;
private static final int FLAG_CLOSED = 1 << 3;
/**
* Open the gate and allow data to flow. Once opened, the gate cannot be closed other than closing the channel.
*
* If the shutdownWrites() or close() method has already been called this will result it in being invoked on the
* delegate.
*/
public void openGate() throws IOException {
int val = state;
if (allAreSet(val, FLAG_GATE_OPEN)) {
return;
}
state |= FLAG_GATE_OPEN;
if (allAreSet(val, FLAG_CLOSED)) {
delegate.close();
} else {
if (allAreSet(val, FLAG_CLOSE_REQUESTED)) {
delegate.shutdownWrites();
}
if (allAreSet(val, FLAG_WRITES_RESUMED)) {
delegate.wakeupWrites();
}
}
}
public boolean isGateOpen() {
return allAreSet(state, FLAG_GATE_OPEN);
}
public XnioWorker getWorker() {
return delegate.getWorker();
}
@Override
public XnioIoThread getIoThread() {
return delegate.getIoThread();
}
public XnioExecutor getWriteThread() {
return delegate.getWriteThread();
}
public ChannelListener.Setter getWriteSetter() {
return writeSetter;
}
public ChannelListener.Setter getCloseSetter() {
return closeSetter;
}
@Override
public int writeFinal(ByteBuffer src) throws IOException {
if (handleGate()) {
return 0;
}
return delegate.writeFinal(src);
}
@Override
public long writeFinal(ByteBuffer[] srcs, int offset, int length) throws IOException {
if (handleGate()) {
return 0;
}
return delegate.writeFinal(srcs, offset, length);
}
@Override
public long writeFinal(ByteBuffer[] srcs) throws IOException {
if (handleGate()) {
return 0;
}
return delegate.writeFinal(srcs);
}
public int write(final ByteBuffer src) throws IOException {
if (handleGate()) {
return 0;
}
return delegate.write(src);
}
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 (handleGate()) {
return 0;
}
return delegate.write(srcs, offset, length);
}
private boolean handleGate() throws ClosedChannelException {
int val = state;
if (anyAreSet(val, FLAG_CLOSE_REQUESTED)) {
throw new ClosedChannelException();
}
if (anyAreClear(val, FLAG_GATE_OPEN)) {
return true;
}
return false;
}
public long transferFrom(final FileChannel src, final long position, final long count) throws IOException {
if (handleGate()) {
return 0;
}
return delegate.transferFrom(src, position, count);
}
public long transferFrom(final StreamSourceChannel source, final long count, final ByteBuffer throughBuffer) throws IOException {
if (handleGate()) {
return 0;
}
return delegate.transferFrom(source, count, throughBuffer);
}
public boolean flush() throws IOException {
if (anyAreClear(state, FLAG_GATE_OPEN)) {
return false;
}
if (anyAreSet(state, FLAG_CLOSED)) {
throw new ClosedChannelException();
}
if (anyAreSet(state, FLAG_CLOSE_REQUESTED)) {
boolean result = delegate.flush();
if (result) {
state |= FLAG_CLOSED;
}
return result;
}
return delegate.flush();
}
public void suspendWrites() {
if (anyAreSet(state, FLAG_GATE_OPEN)) {
delegate.suspendWrites();
} else {
state &= ~FLAG_WRITES_RESUMED;
}
}
public void resumeWrites() {
if (anyAreSet(state, FLAG_GATE_OPEN)) {
delegate.resumeWrites();
} else {
state |= FLAG_WRITES_RESUMED;
}
}
public boolean isWriteResumed() {
if (anyAreSet(state, FLAG_GATE_OPEN)) {
return delegate.isWriteResumed();
} else {
return anyAreSet(state, FLAG_WRITES_RESUMED);
}
}
public void wakeupWrites() {
if (anyAreSet(state, FLAG_GATE_OPEN)) {
delegate.wakeupWrites();
} else {
state |= FLAG_WRITES_RESUMED;
getIoThread().execute(new Runnable() {
@Override
public void run() {
ChannelListeners.invokeChannelListener(GatedStreamSinkChannel.this, writeSetter.get());
}
});
}
}
public void shutdownWrites() throws IOException {
state |= FLAG_CLOSE_REQUESTED;
if (anyAreSet(state, FLAG_GATE_OPEN)) {
delegate.shutdownWrites();
}
}
public void close() throws IOException {
if (allAreSet(state, FLAG_CLOSED)) {
return;
}
state |= FLAG_CLOSED;
if (anyAreSet(state, FLAG_GATE_OPEN)) {
delegate.close();
}
}
public void awaitWritable() throws IOException {
if (allAreClear(state, FLAG_GATE_OPEN)) {
throw new IllegalStateException();//we don't allow this, as it results in thread safety issues
}
delegate.awaitWritable();
}
public void awaitWritable(final long time, final TimeUnit timeUnit) throws IOException {
if (allAreClear(state, FLAG_GATE_OPEN)) {
throw new IllegalStateException();//we don't allow this, as it results in thread safety issues
}
delegate.awaitWritable(time, timeUnit);
}
public boolean isOpen() {
return allAreClear(state, FLAG_CLOSED);
}
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;
}
/**
* Get the underlying channel if the gate is open, else return this channel.
*
* @return the underlying channel, or this channel if the gate is not open
*/
public StreamSinkChannel getChannel() {
return allAreSet(state, FLAG_GATE_OPEN) ? delegate : this;
}
}