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/*-
* ============LICENSE_START=======================================================
* ECOMP Policy Engine
* ================================================================================
* 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.admin;
import java.io.Serializable;
import java.util.LinkedList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import org.openecomp.policy.common.logging.flexlogger.FlexLogger;
import org.openecomp.policy.common.logging.flexlogger.Logger;
/**
* Handle Notifications from the PAP that the PDP Groups have been changed.
* We need a Server Push Broadcaster because there may be multiple Vaadin instances (i.e. Users) that need to be told when a change occurs.
*
* Initially we only update the entire set of PDPGroups in one shot.
*
* (Code copied from Book of Vaadin chapter on Server Push
*
*/
public class PAPNotificationBroadcaster implements Serializable {
/**
*
*/
private static final long serialVersionUID = -2539940306348821754L;
private static Logger logger = FlexLogger.getLogger(PAPNotificationBroadcaster.class);
static ExecutorService executorService = Executors.newSingleThreadExecutor();
/**
* Interface used by all classes that need to be notified when PAP sends an update message.
*
*
*/
public interface PAPNotificationBroadcastListener {
void updateAllGroups();
}
/*
* list of registered listeners
*/
private static LinkedList<PAPNotificationBroadcastListener> listeners =
new LinkedList<PAPNotificationBroadcastListener>();
/**
* Listener registers to hear about updates.
* @param listener
*/
public static synchronized void register(
PAPNotificationBroadcastListener listener) {
listeners.add(listener);
}
/**
* Listener is going away.
*
* @param listener
*/
public static synchronized void unregister(
PAPNotificationBroadcastListener listener) {
listeners.remove(listener);
}
/**
* Tell all listeners about an update.
*
* @param message
*/
public static synchronized void updateAllGroups() {
for (final PAPNotificationBroadcastListener listener: listeners) {
// Original code copied from example:
// executorService.execute(new Runnable() {
// @Override
// public void run() {
// The problem with this is that the execute starts a new Thread, but the thing we are calling (the listener.updateAllGroups)
// happens in this case to ALSO create a new thread, and it locks up because the shared threadpool queue is already locked by this method.
// On application shutdown that left us with a blocked thread, so the process never goes away.
// Since the listener.updateAllGroups does ALL of its work inside a new Runnable thread, there should be no need for this method to also create a thread.
/*
* IMPORTANT:
* All listeners MUST either execute with no possibility of blocking
* OR must start their own threads to handle blocking and concurrent operations.
*/
if (logger.isDebugEnabled()) {
logger.debug("updateAllGroups");
}
listener.updateAllGroups();
}
}
}
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