com.jkoolcloud.tnt4j.streams.configure.zookeeper.ZKConnection.java Source code

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Here is the source code for com.jkoolcloud.tnt4j.streams.configure.zookeeper.ZKConnection.java

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/*
 * Copyright 2014-2017 JKOOL, LLC.
 *
 * 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.
 */

package com.jkoolcloud.tnt4j.streams.configure.zookeeper;

import java.io.Closeable;
import java.io.IOException;
import java.util.concurrent.CountDownLatch;

import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooKeeper;

/**
 * ZooKeeper connection wrapper-helper class.
 * 
 * @version $Revision: 1 $
 */
public class ZKConnection implements Closeable {

    // ZooKeeper instance to access ZooKeeper ensemble
    private ZooKeeper zk;

    /**
     * Connects to ZooKeeper ensemble. Waits until connection establishment is confirmed over watcher.
     *
     * @param connStr
     *            ZooKeeper ensemble connection definition string
     * @return zookeeper instance
     *
     * @throws IOException
     *             if I/O exception occurs while initializing ZooKeeper connection
     * @throws InterruptedException
     *             if the current thread is interrupted while waiting
     *
     * @see #connect(String, int)
     */
    public ZooKeeper connect(String connStr) throws IOException, InterruptedException {
        return connect(connStr, ZKConfigConstants.DEFAULT_CONN_TIMEOUT);
    }

    /**
     * Connects to ZooKeeper ensemble. Waits until connection establishment is confirmed over watcher.
     *
     * @param connStr
     *            ZooKeeper ensemble connection definition string
     * @param timeout
     *            connection timeout
     * @return zookeeper instance
     * 
     * @throws IOException
     *             if I/O exception occurs while initializing ZooKeeper connection
     * @throws InterruptedException
     *             if the current thread is interrupted while waiting
     */
    public ZooKeeper connect(String connStr, int timeout) throws IOException, InterruptedException {
        final CountDownLatch connectedSignal = new CountDownLatch(1);
        zk = new ZooKeeper(connStr, timeout, new Watcher() {
            @Override
            public void process(WatchedEvent we) {
                if (we.getState() == Event.KeeperState.SyncConnected) {
                    connectedSignal.countDown();
                }
            }
        });

        connectedSignal.await();
        return zk;
    }

    /**
     * Checks if connection to {@link org.apache.zookeeper.ZooKeeper} ensemble was performed.
     *
     * @return {@code true} if {@link org.apache.zookeeper.ZooKeeper} instance is not {@code null}, {@code false} -
     *         otherwise
     */
    public boolean isConnected() {
        return zk != null;
    }

    /**
     * Returns {@link org.apache.zookeeper.ZooKeeper} instance connection was established to.
     *
     * @return zookeeper instance
     */
    public ZooKeeper zk() {
        return zk;
    }

    /**
     * Disconnects from ZooKeeper ensemble.
     */
    @Override
    public void close() {
        if (isConnected()) {
            try {
                zk.close();
            } catch (InterruptedException exc) {
            }
        }
    }
}