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/*
* Copyright 2014-2015 Open Networking Laboratory
*
* 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.onosproject.event.impl;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Service;
import org.onlab.util.SharedExecutors;
import org.onosproject.event.AbstractEvent;
import org.onosproject.event.DefaultEventSinkRegistry;
import org.onosproject.event.Event;
import org.onosproject.event.EventDeliveryService;
import org.onosproject.event.EventSink;
import org.slf4j.Logger;
import java.util.TimerTask;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import static com.google.common.base.Preconditions.checkArgument;
import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static org.onlab.util.Tools.groupedThreads;
import static org.slf4j.LoggerFactory.getLogger;
/**
* Simple implementation of an event dispatching service.
*/
@Component(immediate = true)
@Service
public class CoreEventDispatcher extends DefaultEventSinkRegistry
implements EventDeliveryService {
private final Logger log = getLogger(getClass());
// Default number of millis a sink can take to process an event.
private static final long DEFAULT_EXECUTE_MS = 5_000; // ms
private static final long WATCHDOG_MS = 250; // ms
private final BlockingQueue<Event> events = new LinkedBlockingQueue<>();
private final ExecutorService executor =
newSingleThreadExecutor(groupedThreads("onos/event", "dispatch-%d"));
@SuppressWarnings("unchecked")
private static final Event KILL_PILL = new AbstractEvent(null, 0) {
};
private DispatchLoop dispatchLoop;
private long maxProcessMillis = DEFAULT_EXECUTE_MS;
// Means to detect long-running sinks
private TimerTask watchdog;
private EventSink lastSink;
private long lastStart = 0;
private Future<?> dispatchFuture;
@Override
public void post(Event event) {
if (!events.add(event)) {
log.error("Unable to post event {}", event);
}
}
@Activate
public void activate() {
dispatchLoop = new DispatchLoop();
dispatchFuture = executor.submit(dispatchLoop);
watchdog = new Watchdog();
SharedExecutors.getTimer().schedule(watchdog, WATCHDOG_MS, WATCHDOG_MS);
log.info("Started");
}
@Deactivate
public void deactivate() {
dispatchLoop.stop();
watchdog.cancel();
post(KILL_PILL);
log.info("Stopped");
}
@Override
public void setDispatchTimeLimit(long millis) {
checkArgument(millis >= WATCHDOG_MS,
"Time limit must be greater than %s", WATCHDOG_MS);
maxProcessMillis = millis;
}
@Override
public long getDispatchTimeLimit() {
return maxProcessMillis;
}
// Auxiliary event dispatching loop that feeds off the events queue.
private class DispatchLoop implements Runnable {
private volatile boolean stopped;
@Override
public void run() {
stopped = false;
log.info("Dispatch loop initiated");
while (!stopped) {
try {
// Fetch the next event and if it is the kill-pill, bail
Event event = events.take();
if (event == KILL_PILL) {
break;
}
process(event);
} catch (InterruptedException e) {
log.warn("Dispatch loop interrupted");
} catch (Exception e) {
log.warn("Error encountered while dispatching event:", e);
}
}
log.info("Dispatch loop terminated");
}
// Locate the sink for the event class and use it to process the event
@SuppressWarnings("unchecked")
private void process(Event event) {
EventSink sink = getSink(event.getClass());
if (sink != null) {
lastSink = sink;
lastStart = System.currentTimeMillis();
sink.process(event);
lastStart = 0;
} else {
log.warn("No sink registered for event class {}",
event.getClass().getName());
}
}
void stop() {
stopped = true;
}
}
// Monitors event sinks to make sure none take too long to execute.
private class Watchdog extends TimerTask {
@Override
public void run() {
long delta = System.currentTimeMillis() - lastStart;
if (lastStart > 0 && delta > maxProcessMillis) {
lastStart = 0;
log.warn("Event sink {} exceeded execution time limit: {} ms; spawning new dispatch loop",
lastSink.getClass().getName(), delta);
// Notify the sink that it has exceeded its time limit.
lastSink.onProcessLimit();
// Cancel the old dispatch loop and submit a new one.
dispatchLoop.stop();
dispatchLoop = new DispatchLoop();
dispatchFuture.cancel(true);
dispatchFuture = executor.submit(dispatchLoop);
}
}
}
}
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