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/*
* ============LICENSE_START=======================================================
* ONAP PAP
* ================================================================================
* Copyright (C) 2019 AT&T Intellectual Property. All rights reserved.
* Modifications Copyright (C) 2020 Bell Canada. 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.onap.policy.pap.main.comm;
import java.util.Collection;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import org.onap.policy.common.endpoints.event.comm.Topic.CommInfrastructure;
import org.onap.policy.common.endpoints.listeners.TypedMessageListener;
import org.onap.policy.models.pdp.concepts.PdpStatus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Listener for PDP Status messages expected to be received from multiple PDPs. The
* listener "completes" once a message has been seen from all of the PDPs.
*/
public abstract class MultiPdpStatusListener implements TypedMessageListener<PdpStatus> {
private static final Logger logger = LoggerFactory.getLogger(MultiPdpStatusListener.class);
/**
* This is decremented once a message has been received from every PDP.
*/
private final CountDownLatch allSeen = new CountDownLatch(1);
/**
* IDs for which no message has been received yet.
*/
private final Set<String> unseenIds = ConcurrentHashMap.newKeySet();
/**
* Constructs the object.
*
* @param id ID for which to wait
*/
protected MultiPdpStatusListener(String id) {
unseenIds.add(id);
}
/**
* Constructs the object.
*
* @param ids IDs for which to wait
*/
protected MultiPdpStatusListener(Collection<String> ids) {
if (ids.isEmpty()) {
allSeen.countDown();
} else {
unseenIds.addAll(ids);
}
}
/**
* Gets the set of IDs for which messages have not yet been received.
*
* @return the IDs that have not been seen yet
*/
public SortedSet<String> getUnseenIds() {
return new TreeSet<>(unseenIds);
}
/**
* Waits for messages to be received for all PDPs, or until a timeout is reached.
*
* @param timeout the maximum time to wait
* @param unit the time unit of the timeout argument
* @return {@code true} if messages were received for all PDPs, {@code false} if the
* timeout was reached first
* @throws InterruptedException if the current thread is interrupted while waiting
*/
public boolean await(long timeout, TimeUnit unit) throws InterruptedException {
return allSeen.await(timeout, unit);
}
/**
* After giving the event to the subclass via
* {@link #handleEvent(CommInfrastructure, String, PdpStatus)}, this triggers
* completion of {@link #await(long, TimeUnit)}, if all PDPs have received a message.
*/
@Override
public final void onTopicEvent(CommInfrastructure infra, String topic, PdpStatus message) {
String id = null;
try {
id = handleEvent(infra, topic, message);
} catch (RuntimeException e) {
logger.warn("handleEvent failed due to: {}", e.getMessage(), e);
}
if (id == null) {
return;
}
unseenIds.remove(id);
if (unseenIds.isEmpty()) {
allSeen.countDown();
}
}
/**
* Indicates that a message was received for a PDP.
*
* @param infra infrastructure with which the message was received
* @param topic topic on which the message was received
* @param message message that was received
* @return the ID extracted from the message, or {@code null} if it cannot be extracted
*/
protected abstract String handleEvent(CommInfrastructure infra, String topic, PdpStatus message);
}
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