/**
* 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.zookeeper;
import java.util.concurrent.CountDownLatch;
import org.apache.camel.RuntimeCamelException;
import org.apache.camel.util.ObjectHelper;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.Watcher.Event.KeeperState;
import org.apache.zookeeper.ZooKeeper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* <code>ConnectionHolder</code> watches for Connection based events from
* {@link ZooKeeper} and can be used to block until a connection has been
* established.
*/
public class ConnectionHolder implements Watcher {
private static final Logger LOG = LoggerFactory.getLogger(ConnectionHolder.class);
private CountDownLatch connectionLatch = new CountDownLatch(1);
private ZooKeeperConfiguration configuration;
private ZooKeeper zookeeper;
public ConnectionHolder(ZooKeeperConfiguration configuration) {
this.configuration = configuration;
}
public ZooKeeper getZooKeeper() {
if (zookeeper != null) {
return zookeeper;
}
if (configuration.getConnectString() == null) {
throw new RuntimeCamelException("Cannot create ZooKeeper connection as connection string is null. Have servers been configured?");
}
try {
zookeeper = new ZooKeeper(configuration.getConnectString(), configuration.getTimeout(), this);
} catch (Exception e) {
throw ObjectHelper.wrapRuntimeCamelException(e);
}
awaitConnection();
return zookeeper;
}
public boolean isConnected() {
return connectionLatch.getCount() == 0;
}
public void awaitConnection() {
if (LOG.isDebugEnabled()) {
LOG.debug("Awaiting Connection event from Zookeeper cluster {}", configuration.getConnectString());
}
try {
connectionLatch.await();
} catch (InterruptedException e) {
throw ObjectHelper.wrapRuntimeCamelException(e);
}
}
public void process(WatchedEvent event) {
if (event.getState() == KeeperState.SyncConnected) {
connectionLatch.countDown();
}
connectionLatch.countDown();
}
public void closeConnection() {
try {
zookeeper.close();
if (LOG.isDebugEnabled()) {
LOG.debug("Shutting down connection to Zookeeper cluster {}", configuration.getConnectString());
}
} catch (InterruptedException e) {
LOG.warn("Error closing zookeeper connection " + configuration.getConnectString() + ". This exception will be ignored.", e);
}
}
}