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The RabbitMQ Java client library allows Java applications to interface with RabbitMQ.
// Copyright (c) 2007-2020 VMware, Inc. or its affiliates. All rights reserved.
//
// This software, the RabbitMQ Java client library, is triple-licensed under the
// Mozilla Public License 2.0 ("MPL"), the GNU General Public License version 2
// ("GPL") and the Apache License version 2 ("ASL"). For the MPL, please see
// LICENSE-MPL-RabbitMQ. For the GPL, please see LICENSE-GPL2. For the ASL,
// please see LICENSE-APACHE2.
//
// This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND,
// either express or implied. See the LICENSE file for specific language governing
// rights and limitations of this software.
//
// If you have any questions regarding licensing, please contact us at
// [email protected].
package com.rabbitmq.client.impl;
import com.rabbitmq.client.ConnectionFactory;
import com.rabbitmq.client.MetricsCollector;
import com.rabbitmq.client.NoOpMetricsCollector;
import com.rabbitmq.client.ShutdownSignalException;
import com.rabbitmq.utility.IntAllocator;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.*;
/**
* Manages a set of channels, indexed by channel number (1.._channelMax).
*/
public class ChannelManager {
private static final Logger LOGGER = LoggerFactory.getLogger(ChannelManager.class);
/** Monitor for _channelMap and channelNumberAllocator */
private final Object monitor = new Object();
/** Mapping from 1.._channelMax to {@link ChannelN} instance */
private final Map _channelMap = new HashMap();
private final IntAllocator channelNumberAllocator;
private final ConsumerWorkService workService;
private final Set shutdownSet = new HashSet();
/** Maximum channel number available on this connection. */
private final int _channelMax;
private ExecutorService shutdownExecutor;
private final ThreadFactory threadFactory;
private int channelShutdownTimeout = (int) ((ConnectionFactory.DEFAULT_HEARTBEAT * AMQConnection.CHANNEL_SHUTDOWN_TIMEOUT_MULTIPLIER) * 1000);
protected final MetricsCollector metricsCollector;
public int getChannelMax(){
return _channelMax;
}
public ChannelManager(ConsumerWorkService workService, int channelMax) {
this(workService, channelMax, Executors.defaultThreadFactory());
}
public ChannelManager(ConsumerWorkService workService, int channelMax, ThreadFactory threadFactory) {
this(workService, channelMax, threadFactory, new NoOpMetricsCollector());
}
public ChannelManager(ConsumerWorkService workService, int channelMax, ThreadFactory threadFactory, MetricsCollector metricsCollector) {
if (channelMax < 0)
throw new IllegalArgumentException("create ChannelManager: 'channelMax' must be greater or equal to 0.");
if (channelMax == 0) {
// The framing encoding only allows for unsigned 16-bit integers
// for the channel number
channelMax = (1 << 16) - 1;
}
_channelMax = channelMax;
channelNumberAllocator = new IntAllocator(1, channelMax);
this.workService = workService;
this.threadFactory = threadFactory;
this.metricsCollector = metricsCollector;
}
/**
* Looks up a channel on this connection.
* @param channelNumber the number of the required channel
* @return the channel on this connection with number channelNumber
* @throws UnknownChannelException if there is no channel with number channelNumber on this connection
*/
public ChannelN getChannel(int channelNumber) {
synchronized (this.monitor) {
ChannelN ch = _channelMap.get(channelNumber);
if(ch == null) throw new UnknownChannelException(channelNumber);
return ch;
}
}
/**
* Handle shutdown. All the managed {@link com.rabbitmq.client.Channel Channel}s are shutdown.
* @param signal reason for shutdown
*/
public void handleSignal(final ShutdownSignalException signal) {
Set channels;
synchronized(this.monitor) {
channels = new HashSet(_channelMap.values());
}
for (final ChannelN channel : channels) {
releaseChannelNumber(channel);
// async shutdown if possible
// see https://github.com/rabbitmq/rabbitmq-java-client/issues/194
Runnable channelShutdownRunnable = new Runnable() {
@Override
public void run() {
channel.processShutdownSignal(signal, true, true);
}
};
if(this.shutdownExecutor == null) {
channelShutdownRunnable.run();
} else {
Future channelShutdownTask = this.shutdownExecutor.submit(channelShutdownRunnable);
try {
channelShutdownTask.get(channelShutdownTimeout, TimeUnit.MILLISECONDS);
} catch (Exception e) {
LOGGER.warn("Couldn't properly close channel {} on shutdown after waiting for {} ms", channel.getChannelNumber(), channelShutdownTimeout);
channelShutdownTask.cancel(true);
}
}
shutdownSet.add(channel.getShutdownLatch());
channel.notifyListeners();
}
scheduleShutdownProcessing();
}
private void scheduleShutdownProcessing() {
final Set sdSet = new HashSet(shutdownSet);
final ConsumerWorkService ssWorkService = workService;
Runnable target = new Runnable() {
@Override
public void run() {
for (CountDownLatch latch : sdSet) {
try {
int shutdownTimeout = ssWorkService.getShutdownTimeout();
if (shutdownTimeout == 0) {
latch.await();
} else {
boolean completed = latch.await(shutdownTimeout, TimeUnit.MILLISECONDS);
if (!completed) {
LOGGER.warn("Consumer dispatcher for channel didn't shutdown after waiting for {} ms", shutdownTimeout);
}
}
} catch (Throwable e) {
/*ignored*/
}
}
ssWorkService.shutdown();
}
};
if(this.shutdownExecutor != null) {
shutdownExecutor.execute(target);
} else {
Thread shutdownThread = Environment.newThread(threadFactory,
target,
"ConsumerWorkService shutdown monitor",
true);
shutdownThread.start();
}
}
public ChannelN createChannel(AMQConnection connection) throws IOException {
ChannelN ch;
synchronized (this.monitor) {
int channelNumber = channelNumberAllocator.allocate();
if (channelNumber == -1) {
return null;
} else {
ch = addNewChannel(connection, channelNumber);
}
}
ch.open(); // now that it's been safely added
return ch;
}
public ChannelN createChannel(AMQConnection connection, int channelNumber) throws IOException {
ChannelN ch;
synchronized (this.monitor) {
if (channelNumberAllocator.reserve(channelNumber)) {
ch = addNewChannel(connection, channelNumber);
} else {
return null;
}
}
ch.open(); // now that it's been safely added
return ch;
}
private ChannelN addNewChannel(AMQConnection connection, int channelNumber) {
if (_channelMap.containsKey(channelNumber)) {
// That number's already allocated! Can't do it
// This should never happen unless something has gone
// badly wrong with our implementation.
throw new IllegalStateException("We have attempted to "
+ "create a channel with a number that is already in "
+ "use. This should never happen. "
+ "Please report this as a bug.");
}
ChannelN ch = instantiateChannel(connection, channelNumber, this.workService);
_channelMap.put(ch.getChannelNumber(), ch);
return ch;
}
protected ChannelN instantiateChannel(AMQConnection connection, int channelNumber, ConsumerWorkService workService) {
return new ChannelN(connection, channelNumber, workService, this.metricsCollector);
}
/**
* Remove the channel from the channel map and free the number for re-use.
* This method must be safe to call multiple times on the same channel. If
* it is not then things go badly wrong.
*/
public void releaseChannelNumber(ChannelN channel) {
// Warning, here be dragons. Not great big ones, but little baby ones
// which will nibble on your toes and occasionally trip you up when
// you least expect it. (Pixies? HP2)
// Basically, there's a race that can end us up here. It almost never
// happens, but it's easier to repair it when it does than prevent it
// from happening in the first place.
// If we end up doing a Channel.close in one thread and a Channel.open
// with the same channel number in another, the two can overlap in such
// a way as to cause disconnectChannel on the old channel to try to
// remove the new one. Ideally we would fix this race at the source,
// but it's much easier to just catch it here.
synchronized (this.monitor) {
int channelNumber = channel.getChannelNumber();
ChannelN existing = _channelMap.remove(channelNumber);
// Nothing to do here. Move along.
if (existing == null)
return;
// Oops, we've gone and stomped on someone else's channel. Put it
// back and pretend we didn't touch it.
else if (existing != channel) {
_channelMap.put(channelNumber, existing);
return;
}
channelNumberAllocator.free(channelNumber);
}
}
public ExecutorService getShutdownExecutor() {
return shutdownExecutor;
}
public void setShutdownExecutor(ExecutorService shutdownExecutor) {
this.shutdownExecutor = shutdownExecutor;
}
/**
* Set the shutdown timeout for channels.
* This is the amount of time the manager waits for a channel to
* shutdown before giving up.
* Works only when the {@code shutdownExecutor} property is set.
* Default to {@link com.rabbitmq.client.ConnectionFactory#DEFAULT_HEARTBEAT} + 5 % seconds
* @param channelShutdownTimeout shutdown timeout in milliseconds
*/
public void setChannelShutdownTimeout(int channelShutdownTimeout) {
this.channelShutdownTimeout = channelShutdownTimeout;
}
}