001/**
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.impl.cluster;
018
019import java.util.ArrayList;
020import java.util.List;
021import java.util.Optional;
022import java.util.concurrent.locks.StampedLock;
023import java.util.function.Consumer;
024
025import org.apache.camel.CamelContext;
026import org.apache.camel.cluster.CamelClusterEventListener;
027import org.apache.camel.cluster.CamelClusterMember;
028import org.apache.camel.cluster.CamelClusterService;
029import org.apache.camel.cluster.CamelClusterView;
030import org.apache.camel.support.ServiceSupport;
031import org.apache.camel.util.concurrent.LockHelper;
032
033public abstract class AbstractCamelClusterView extends ServiceSupport implements CamelClusterView {
034    private final CamelClusterService clusterService;
035    private final String namespace;
036    private final List<CamelClusterEventListener> listeners;
037    private final StampedLock lock;
038    private CamelContext camelContext;
039
040    protected AbstractCamelClusterView(CamelClusterService cluster, String namespace) {
041        this.clusterService = cluster;
042        this.namespace = namespace;
043        this.listeners = new ArrayList<>();
044        this.lock = new StampedLock();
045    }
046
047    @Override
048    public void setCamelContext(CamelContext camelContext) {
049        this.camelContext = camelContext;
050    }
051
052    @Override
053    public CamelContext getCamelContext() {
054        return camelContext;
055    }
056
057    @Override
058    public CamelClusterService getClusterService() {
059        return this.clusterService;
060    }
061
062    @Override
063    public String getNamespace() {
064        return this.namespace;
065    }
066
067    @Override
068    public void addEventListener(CamelClusterEventListener listener) {
069        if (listener == null) {
070            return;
071        }
072
073        LockHelper.doWithWriteLock(
074            lock,
075            () -> {
076                listeners.add(listener);
077
078                if (isRunAllowed()) {
079                    // if the view has already been started, fire known events so
080                    // the consumer can catch up.
081
082                    if (CamelClusterEventListener.Leadership.class.isInstance(listener)) {
083                        CamelClusterEventListener.Leadership.class.cast(listener).leadershipChanged(this, getLeader());
084                    }
085
086                    if (CamelClusterEventListener.Membership.class.isInstance(listener)) {
087                        CamelClusterEventListener.Membership ml = CamelClusterEventListener.Membership.class.cast(listener);
088
089                        for (CamelClusterMember member: getMembers()) {
090                            ml.memberAdded(this, member);
091                        }
092                    }
093                }
094            }
095        );
096    }
097
098    @Override
099    public void removeEventListener(CamelClusterEventListener listener) {
100        if (listener == null) {
101            return;
102        }
103
104        LockHelper.doWithWriteLock(lock, () -> listeners.removeIf(l -> l == listener));
105    }
106
107    // **************************************
108    // Events
109    // **************************************
110
111    private <T extends CamelClusterEventListener> void doWithListener(Class<T> type, Consumer<T> consumer) {
112        LockHelper.doWithReadLock(
113            lock,
114            () -> {
115                for (int i = 0; i < listeners.size(); i++) {
116                    CamelClusterEventListener listener = listeners.get(i);
117
118                    if (type.isInstance(listener)) {
119                        consumer.accept(type.cast(listener));
120                    }
121                }
122            }
123        );
124    }
125
126    protected void fireLeadershipChangedEvent(Optional<CamelClusterMember> leader) {
127        doWithListener(
128            CamelClusterEventListener.Leadership.class,
129            listener -> listener.leadershipChanged(this, leader)
130        );
131    }
132
133    protected void fireMemberAddedEvent(CamelClusterMember member) {
134        doWithListener(
135            CamelClusterEventListener.Membership.class,
136            listener -> listener.memberAdded(this, member)
137        );
138    }
139
140    protected void fireMemberRemovedEvent(CamelClusterMember member) {
141        doWithListener(
142            CamelClusterEventListener.Membership.class,
143            listener -> listener.memberRemoved(this, member)
144        );
145    }
146}