org.kiji.maven.plugins.hbase.PluginMiniHBaseClusterSingleton.java Source code

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Here is the source code for org.kiji.maven.plugins.hbase.PluginMiniHBaseClusterSingleton.java

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/**
 * Licensed to WibiData, Inc. under one or more contributor license
 * agreements.  See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.  WibiData, Inc.
 * 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.kiji.maven.plugins.hbase;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.maven.plugin.logging.Log;

/**
 * A singleton instance of a mini HBase cluster.
 */
public enum PluginMiniHBaseClusterSingleton {
    /**
     * The singleton instance.
     */
    INSTANCE;

    /**
     * The thread that runs the mini HBase cluster.
     */
    private PluginMiniHBaseClusterThread _miniHBaseClusterThread;
    /**
     * The HBase cluster being run.
     */
    private PluginMiniHBaseCluster _miniCluster;

    /**
     * Starts the HBase cluster and blocks until it is ready.
     *
     * @param log                The maven log.
     * @param alsoStartMapReduce Whether to also start a mini MapReduce cluster.
     * @param conf               Hadoop configuration for the cluster.
     * @throws IOException If there is an error.
     */
    public void startAndWaitUntilReady(final Log log, final boolean alsoStartMapReduce, final Configuration conf)
            throws IOException {
        _miniCluster = new PluginMiniHBaseCluster(log, alsoStartMapReduce, conf);
        _miniHBaseClusterThread = new PluginMiniHBaseClusterThread(log, _miniCluster);

        log.info("Starting new thread...");
        _miniHBaseClusterThread.start();

        // Wait for the cluster to be ready.
        log.info("Waiting for cluster to be ready...");
        while (!_miniHBaseClusterThread.isClusterReady()) {
            try {
                Thread.sleep(1000);
            } catch (final InterruptedException e) {
                log.info("Still waiting...");
            }
        }
        log.info("Finished waiting for HBase cluster thread.");
    }

    /**
     * Provides access to the cluster configuration after it has started.
     *
     * @return The configuration.
     */
    public Configuration getClusterConfiguration() {
        if (null == _miniCluster) {
            throw new IllegalStateException("The cluster has not started yet.");
        }
        return _miniCluster.getConfiguration();
    }

    /**
     * Stops the HBase cluster and blocks until is has been shutdown completely.
     *
     * @param log The maven log.
     */
    public void stop(final Log log) {
        if (null == _miniCluster) {
            log.error("Attempted to stop a cluster, but no cluster was ever started in this process.");
            return;
        }

        log.info("Stopping the HBase cluster thread...");
        _miniHBaseClusterThread.stopClusterGracefully();
        while (_miniHBaseClusterThread.isAlive()) {
            try {
                _miniHBaseClusterThread.join();
            } catch (final InterruptedException e) {
                log.debug("HBase cluster thread interrupted.");
            }
        }
        log.info("HBase cluster thread stopped.");
    }
}