ZookeeperGroupListenerSupport.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
package org.apache.camel.component.zookeepermaster;

import org.apache.camel.Endpoint;
import org.apache.camel.component.zookeepermaster.group.Group;
import org.apache.camel.component.zookeepermaster.group.GroupListener;
import org.apache.camel.util.IOHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ZookeeperGroupListenerSupport extends ZookeeperGroupSupport implements GroupListener {

    private static final transient Logger LOG = LoggerFactory.getLogger(ZookeeperGroupListenerSupport.class);
    private Group<CamelNodeState> singleton;
    private final String clusterPath;
    private final Endpoint endpoint;
    private final Runnable onLockAcquired;
    private final Runnable onDisconnected;

    public ZookeeperGroupListenerSupport(String clusterPath, Endpoint endpoint, Runnable onLockAcquired, Runnable onDisconnected) {
        this.clusterPath = clusterPath;
        this.endpoint = endpoint;
        this.onLockAcquired = onLockAcquired;
        this.onDisconnected = onDisconnected;
    }

    public void updateState(CamelNodeState state) {
        singleton.update(state);
    }

    @Override
    protected void doStart() throws Exception {
        super.doStart();

        this.singleton = createGroup(clusterPath);
        this.singleton.add(this);
        singleton.start();
    }

    @Override
    protected void doStop() throws Exception {
        IOHelper.close(singleton);
        super.doStop();
    }

    public String getClusterPath() {
        return clusterPath;
    }

    public Group<CamelNodeState> getGroup() {
        return singleton;
    }

    @Override
    public void groupEvent(Group group, GroupEvent event) {
        switch (event) {
        case CONNECTED:
            break;
        case CHANGED:
            if (singleton.isConnected()) {
                if (singleton.isMaster()) {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Master/Standby endpoint is Master for:  " + endpoint + " in " + endpoint.getCamelContext());
                    }
                    onLockOwned();
                } else {
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Master/Standby endpoint is Standby for: " + endpoint + " in " + endpoint.getCamelContext());
                    }
                }
            }
            break;
        case DISCONNECTED:
            try {
                LOG.info("Disconnecting as master. Stopping consumer: {}", endpoint);
                onDisconnected();
            } catch (Exception e) {
                LOG.warn("Failed to stop master consumer for: " + endpoint + ". This exception is ignored.", e);
            }
            break;
        default:
            // noop
        }
    }

    protected void onDisconnected() {
        onDisconnected.run();
    }

    protected void onLockOwned() {
        onLockAcquired.run();
    }

}