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/*
* Copyright 2014 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;
import org.slf4j.Logger;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
import static com.google.common.base.Preconditions.checkNotNull;
import static org.slf4j.LoggerFactory.getLogger;
/**
* Base implementation of an event sink and a registry capable of tracking
* listeners and dispatching events to them as part of event sink processing.
*/
public class ListenerRegistry<E extends Event, L extends EventListener<E>>
implements ListenerService<E, L>, EventSink<E> {
private static final long LIMIT = 1_800; // ms
private final Logger log = getLogger(getClass());
private long lastStart;
private L lastListener;
/**
* Set of listeners that have registered.
*/
protected final Set<L> listeners = new CopyOnWriteArraySet<>();
@Override
public void addListener(L listener) {
checkNotNull(listener, "Listener cannot be null");
listeners.add(listener);
}
@Override
public void removeListener(L listener) {
checkNotNull(listener, "Listener cannot be null");
if (!listeners.remove(listener)) {
log.warn("Listener {} not registered", listener);
}
}
@Override
public void process(E event) {
for (L listener : listeners) {
try {
lastListener = listener;
lastStart = System.currentTimeMillis();
if (listener.isRelevant(event)) {
listener.event(event);
}
lastStart = 0;
} catch (Exception error) {
reportProblem(event, error);
}
}
}
@Override
public void onProcessLimit() {
if (lastStart > 0) {
long duration = System.currentTimeMillis() - lastStart;
if (duration > LIMIT) {
log.error("Listener {} exceeded execution time limit: {} ms; ejected",
lastListener.getClass().getName(),
duration);
removeListener(lastListener);
}
lastStart = 0;
}
}
/**
* Reports a problem encountered while processing an event.
*
* @param event event being processed
* @param error error encountered while processing
*/
protected void reportProblem(E event, Throwable error) {
log.warn("Exception encountered while processing event " + event, error);
}
}
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