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Code Issues Releases Wiki Activity

Inroduce AsyncButOrdered

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This commit is contained in:
Florian Schmaus 2018-04-08 21:21:50 +02:00
parent 1acfd872a7
commit 476fdf99a1
11 changed files with 414 additions and 272 deletions
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38
smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java
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@ -29,13 +29,12 @@ import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.locks.Lock;
@ -86,7 +85,6 @@ import org.jivesoftware.smack.util.DNSUtil;
import org.jivesoftware.smack.util.Objects;
import org.jivesoftware.smack.util.PacketParserUtils;
import org.jivesoftware.smack.util.ParserUtils;
import org.jivesoftware.smack.util.SmackExecutorThreadFactory;
import org.jivesoftware.smack.util.StringUtils;
import org.jivesoftware.smack.util.dns.HostAddress;
@ -266,14 +264,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
}
});
/**
* A executor service used to invoke the callbacks of synchronous stanza listeners. We use a executor service to
* decouple incoming stanza processing from callback invocation. It is important that order of callback invocation
* is the same as the order of the incoming stanzas. Therefore we use a <i>single</i> threaded executor service.
*/
private final ExecutorService singleThreadedExecutorService = new ThreadPoolExecutor(0, 1, 30L,
TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(),
new SmackExecutorThreadFactory(this, "Single Threaded Executor"));
private static final AsyncButOrdered<AbstractXMPPConnection> ASYNC_BUT_ORDERED = new AsyncButOrdered<>();
/**
* The used host to establish the connection to
@ -1112,10 +1103,10 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
LOGGER.log(Level.WARNING, "Exception while sending error IQ to unkown IQ request", e);
}
} else {
ExecutorService executorService = null;
Executor executorService = null;
switch (iqRequestHandler.getMode()) {
case sync:
executorService = singleThreadedExecutorService;
executorService = ASYNC_BUT_ORDERED.asExecutorFor(this);
break;
case async:
executorService = CACHED_EXECUTOR_SERVICE;
@ -1192,7 +1183,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
// Decouple incoming stanza processing from listener invocation. Unlike async listeners, this uses a single
// threaded executor service and therefore keeps the order.
singleThreadedExecutorService.execute(new Runnable() {
ASYNC_BUT_ORDERED.performAsyncButOrdered(this, new Runnable() {
@Override
public void run() {
for (StanzaListener listener : listenersToNotify) {
@ -1207,7 +1198,6 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
}
}
});
}
/**
@ -1350,24 +1340,6 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
return this.fromMode;
}
@Override
protected void finalize() throws Throwable {
LOGGER.fine("finalizing " + this + ": Shutting down executor services");
try {
// It's usually not a good idea to rely on finalize. But this is the easiest way to
// avoid the "Smack Listener Processor" leaking. The thread(s) of the executor have a
// reference to their ExecutorService which prevents the ExecutorService from being
// gc'ed. It is possible that the XMPPConnection instance is gc'ed while the
// listenerExecutor ExecutorService call not be gc'ed until it got shut down.
singleThreadedExecutorService.shutdownNow();
} catch (Throwable t) {
LOGGER.log(Level.WARNING, "finalize() threw throwable", t);
}
finally {
super.finalize();
}
}
protected final void parseFeatures(XmlPullParser parser) throws Exception {
streamFeatures.clear();
final int initialDepth = parser.getDepth();

142
smack-core/src/main/java/org/jivesoftware/smack/AsyncButOrdered.java Normal file
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@ -0,0 +1,142 @@
/**
*
* Copyright 2018 Florian Schmaus
*
* 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.jivesoftware.smack;
import java.util.Map;
import java.util.Queue;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executor;
/**
* Helper class to perform an operation asynchronous but keeping the order in respect to a given key.
* <p>
* A typical use pattern for this helper class consists of callbacks for an abstract entity where the order of callbacks
* matters, which eventually call user code in form of listeners. Since the order the callbacks matters, you need to use
* synchronous connection listeners. But if those listeners would invoke the user provided listeners, and if those user
* provided listeners would take a long time to complete, or even worse, block, then Smack's total progress is stalled,
* since synchronous connection listeners are invoked from the main event loop.
* </p>
* <p>
* It is common for those situations that the order of callbacks is not globally important, but only important in
* respect to an particular entity. Take chat state notifications (CSN) for example: Assume there are two contacts which
* send you CSNs. If a contact sends you first 'active' and then 'inactive, it is crucial that first the listener is
* called with 'active' and afterwards with 'inactive'. But if there is another contact is sending 'composing' followed
* by 'paused', then it is also important that the listeners are invoked in the correct order, but the order in which
* the listeners for those two contacts are invoked does not matter.
* </p>
* <p>
* Using this helper class, one would call {@link #performAsyncButOrdered(Object, Runnable)} which the remote contacts
* JID as first argument and a {@link Runnable} invoking the user listeners as second. This class guarantees that
* runnables of subsequent invocations are always executed after the runnables of previous invocations using the same
* key.
* </p>
*
* @param <K> the type of the key
* @since 4.3
*/
public class AsyncButOrdered<K> {
private final Map<K, Queue<Runnable>> pendingRunnables = new WeakHashMap<>();
private final Map<K, Boolean> threadActiveMap = new WeakHashMap<>();
/**
* Invoke the given {@link Runnable} asynchronous but ordered in respect to the given key.
*
* @param key the key deriving the order
* @param runnable the {@link Runnable} to run
* @return true if a new thread was created
*/
public boolean performAsyncButOrdered(K key, Runnable runnable) {
Queue<Runnable> keyQueue;
synchronized (pendingRunnables) {
keyQueue = pendingRunnables.get(key);
if (keyQueue == null) {
keyQueue = new ConcurrentLinkedQueue<>();
pendingRunnables.put(key, keyQueue);
}
}
keyQueue.add(runnable);
boolean newHandler;
synchronized (threadActiveMap) {
Boolean threadActive = threadActiveMap.get(key);
if (threadActive == null) {
threadActive = false;
threadActiveMap.put(key, threadActive);
}
newHandler = !threadActive;
if (newHandler) {
Handler handler = new Handler(keyQueue, key);
threadActiveMap.put(key, true);
AbstractXMPPConnection.asyncGo(handler);
}
}
return newHandler;
}
public Executor asExecutorFor(final K key) {
return new Executor() {
@Override
public void execute(Runnable runnable) {
performAsyncButOrdered(key, runnable);
}
};
}
private class Handler implements Runnable {
private final Queue<Runnable> keyQueue;
private final K key;
Handler(Queue<Runnable> keyQueue, K key) {
this.keyQueue = keyQueue;
this.key = key;
}
@Override
public void run() {
mainloop:
while (true) {
Runnable runnable = null;
while ((runnable = keyQueue.poll()) != null) {
try {
runnable.run();
} catch (Throwable t) {
// The run() method threw, this handler thread is going to terminate because of that. Ensure we note
// that in the map.
synchronized (threadActiveMap) {
threadActiveMap.put(key, false);
}
throw t;
}
}
synchronized (threadActiveMap) {
// If the queue is empty, stop this handler, otherwise continue looping.
if (keyQueue.isEmpty()) {
threadActiveMap.put(key, false);
break mainloop;
}
}
}
}
}
}

44
smack-core/src/main/java/org/jivesoftware/smack/util/SmackExecutorThreadFactory.java
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@ -1,44 +0,0 @@
/**
*
* Copyright 2014-2015 Florian Schmaus
*
* 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.jivesoftware.smack.util;
import java.util.concurrent.ThreadFactory;
import org.jivesoftware.smack.XMPPConnection;
/**
* SmackExecutorThreadFactory creates daemon threads with a particular name. Note that you should
* not use anonymous inner classes for thread factories in order to prevent threads from leaking.
*/
public final class SmackExecutorThreadFactory implements ThreadFactory {
private final int connectionCounterValue;
private final String name;
private int count = 0;
public SmackExecutorThreadFactory(XMPPConnection connection, String name) {
this.connectionCounterValue = connection.getConnectionCounter();
this.name = name;
}
@Override
public Thread newThread(Runnable runnable) {
Thread thread = new Thread(runnable);
thread.setName("Smack-" + name + ' ' + count++ + " (" + connectionCounterValue + ")");
thread.setDaemon(true);
return thread;
}
}