001/*
002 * (C) Copyright 2017 Nuxeo (http://nuxeo.com/) and others.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 *
016 * Contributors:
017 *     Florent Guillaume
018 */
019package org.nuxeo.runtime.pubsub;
020
021import org.apache.commons.logging.Log;
022import org.apache.commons.logging.LogFactory;
023
024/**
025 * Encapsulates invalidations management through the {@link PubSubService}.
026 *
027 * @since 9.3
028 */
029public abstract class AbstractPubSubInvalidationsAccumulator<T extends SerializableAccumulableInvalidations>
030        extends AbstractPubSubBroker<T> {
031
032    private static final Log log = LogFactory.getLog(AbstractPubSubInvalidationsAccumulator.class);
033
034    protected volatile T bufferedInvalidations;
035
036    /** Constructs new empty invalidations, of type {@link T}. */
037    public abstract T newInvalidations();
038
039    @Override
040    public void initialize(String topic, String discriminator) {
041        bufferedInvalidations = newInvalidations();
042        super.initialize(topic, discriminator);
043    }
044
045    @Override
046    public void close() {
047        super.close();
048        // not null to avoid crashing subscriber thread still in flight
049        bufferedInvalidations = newInvalidations();
050    }
051
052    /**
053     * Sends invalidations to other nodes.
054     */
055    public void sendInvalidations(T invalidations) {
056        sendMessage(invalidations);
057    }
058
059    @Override
060    public void receivedMessage(T invalidations) {
061        if (log.isTraceEnabled()) {
062            log.trace("Received invalidations: " + invalidations);
063        }
064        synchronized (this) {
065            bufferedInvalidations.add(invalidations);
066        }
067    }
068
069    /**
070     * Receives invalidations from other nodes.
071     */
072    public T receiveInvalidations() {
073        T newInvalidations = newInvalidations();
074        T invalidations;
075        synchronized (this) {
076            invalidations = bufferedInvalidations;
077            bufferedInvalidations = newInvalidations;
078        }
079        if (log.isTraceEnabled()) {
080            log.trace("Received invalidations: " + invalidations);
081        }
082        return invalidations;
083    }
084
085}