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/*-
* ============LICENSE_START=======================================================
* policy-endpoints
* ================================================================================
* Copyright (C) 2017 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* 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.
* ============LICENSE_END=========================================================
*/
package org.openecomp.policy.drools.event.comm.bus.internal;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.collections4.queue.CircularFifoQueue;
import org.openecomp.policy.drools.event.comm.Topic;
import org.openecomp.policy.drools.event.comm.TopicListener;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public abstract class TopicBase implements Topic {
/**
* logger
*/
private static Logger logger = LoggerFactory.getLogger(TopicBase.class);
/**
* list of servers
*/
protected List<String> servers;
/**
* Topic
*/
protected String topic;
/**
* event cache
*/
protected CircularFifoQueue<String> recentEvents = new CircularFifoQueue<String>(10);
/**
* Am I running?
* reflects invocation of start()/stop()
* !locked & start() => alive
* stop() => !alive
*/
protected volatile boolean alive = false;
/**
* Am I locked?
* reflects invocation of lock()/unlock() operations
* locked => !alive (but not in the other direction necessarily)
* locked => !offer, !run, !start, !stop (but this last one is obvious
* since locked => !alive)
*/
protected volatile boolean locked = false;
/**
* All my subscribers for new message notifications
*/
protected final ArrayList<TopicListener> topicListeners = new ArrayList<TopicListener>();
/**
* Instantiates a new Topic Base
*
* @param servers list of servers
* @param topic topic name
*
* @return a Topic Base
* @throws IllegalArgumentException if invalid parameters are present
*/
public TopicBase(List<String> servers, String topic) throws IllegalArgumentException {
if (servers == null || servers.isEmpty()) {
throw new IllegalArgumentException("Server(s) must be provided");
}
if (topic == null || topic.isEmpty()) {
throw new IllegalArgumentException("A Topic must be provided");
}
this.servers = servers;
this.topic = topic;
}
@Override
public void register(TopicListener topicListener)
throws IllegalArgumentException {
logger.info("{}: registering {}", this, topicListener);
synchronized(this) {
if (topicListener == null)
throw new IllegalArgumentException("TopicListener must be provided");
for (TopicListener listener: this.topicListeners) {
if (listener == topicListener) return;
}
this.topicListeners.add(topicListener);
}
}
@Override
public void unregister(TopicListener topicListener) {
logger.info("{}: unregistering {}", this, topicListener);
synchronized (this) {
if (topicListener == null)
throw new IllegalArgumentException("TopicListener must be provided");
this.topicListeners.remove(topicListener);
}
}
/**
* broadcast event to all listeners
*
* @param message the event
* @return true if all notifications are performed with no error, false otherwise
*/
protected boolean broadcast(String message) {
List<TopicListener> snapshotListeners = this.snapshotTopicListeners();
boolean success = true;
for (TopicListener topicListener: snapshotListeners) {
try {
topicListener.onTopicEvent(this.getTopicCommInfrastructure(), this.topic, message);
} catch (Exception e) {
logger.warn("{}: notification error @ {} because of {}",
this, topicListener, e.getMessage(), e);
success = false;
}
}
return success;
}
/**
* take a snapshot of current topic listeners
*
* @return the topic listeners
*/
protected synchronized List<TopicListener> snapshotTopicListeners() {
@SuppressWarnings("unchecked")
List<TopicListener> listeners = (List<TopicListener>) topicListeners.clone();
return listeners;
}
@Override
public boolean lock() {
logger.info("{}: locking", this);
synchronized (this) {
if (this.locked)
return true;
this.locked = true;
}
return this.stop();
}
@Override
public boolean unlock() {
logger.info("{}: unlocking", this);
synchronized(this) {
if (!this.locked)
return true;
this.locked = false;
}
try {
return this.start();
} catch (Exception e) {
logger.warn("{}: cannot after unlocking because of {}", this, e.getMessage(), e);
return false;
}
}
@Override
public boolean isLocked() {
return this.locked;
}
@Override
public String getTopic() {
return topic;
}
@Override
public boolean isAlive() {
return this.alive;
}
@Override
public List<String> getServers() {
return servers;
}
@Override
public synchronized String[] getRecentEvents() {
String[] events = new String[recentEvents.size()];
return recentEvents.toArray(events);
}
@Override
public String toString() {
return "TopicBase [servers=" + servers + ", topic=" + topic + ", #recentEvents=" + recentEvents.size() + ", locked="
+ locked + ", #topicListeners=" + topicListeners.size() + "]";
}
}
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