org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.java Source code

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Here is the source code for org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.java

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/**
 * 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.hadoop.metrics2.lib;

import java.util.concurrent.atomic.AtomicReference;
import javax.management.ObjectName;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.metrics2.MetricsException;
import org.apache.hadoop.metrics2.MetricsSystem;
import org.apache.hadoop.metrics2.impl.MetricsSystemImpl;

import com.google.common.annotations.VisibleForTesting;

/**
 * The default metrics system singleton. This class is used by all the daemon
 * processes(such as NameNode, DataNode, JobTracker etc.). During daemon process
 * initialization the processes call {@link DefaultMetricsSystem#init(String)}
 * to initialize the {@link MetricsSystem}.
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public enum DefaultMetricsSystem {
    INSTANCE; // the singleton

    private AtomicReference<MetricsSystem> impl = new AtomicReference<MetricsSystem>(new MetricsSystemImpl());

    @VisibleForTesting
    volatile boolean miniClusterMode = false;

    transient final UniqueNames mBeanNames = new UniqueNames();
    transient final UniqueNames sourceNames = new UniqueNames();

    /**
     * Convenience method to initialize the metrics system
     * @param prefix  for the metrics system configuration
     * @return the metrics system instance
     */
    public static MetricsSystem initialize(String prefix) {
        return INSTANCE.init(prefix);
    }

    MetricsSystem init(String prefix) {
        return impl.get().init(prefix);
    }

    /**
     * @return the metrics system object
     */
    public static MetricsSystem instance() {
        return INSTANCE.getImpl();
    }

    /**
     * Shutdown the metrics system
     */
    public static void shutdown() {
        INSTANCE.shutdownInstance();
    }

    void shutdownInstance() {
        boolean last = impl.get().shutdown();
        if (last)
            synchronized (this) {
                mBeanNames.map.clear();
                sourceNames.map.clear();
            }
    }

    @InterfaceAudience.Private
    public static MetricsSystem setInstance(MetricsSystem ms) {
        return INSTANCE.setImpl(ms);
    }

    MetricsSystem setImpl(MetricsSystem ms) {
        return impl.getAndSet(ms);
    }

    MetricsSystem getImpl() {
        return impl.get();
    }

    @VisibleForTesting
    public static void setMiniClusterMode(boolean choice) {
        INSTANCE.miniClusterMode = choice;
    }

    @VisibleForTesting
    public static boolean inMiniClusterMode() {
        return INSTANCE.miniClusterMode;
    }

    @InterfaceAudience.Private
    public static ObjectName newMBeanName(String name) {
        return INSTANCE.newObjectName(name);
    }

    @InterfaceAudience.Private
    public static void removeMBeanName(ObjectName name) {
        INSTANCE.removeObjectName(name.toString());
    }

    @InterfaceAudience.Private
    public static void removeSourceName(String name) {
        INSTANCE.removeSource(name);
    }

    @InterfaceAudience.Private
    public static String sourceName(String name, boolean dupOK) {
        return INSTANCE.newSourceName(name, dupOK);
    }

    synchronized ObjectName newObjectName(String name) {
        try {
            if (mBeanNames.map.containsKey(name) && !miniClusterMode) {
                throw new MetricsException(name + " already exists!");
            }
            return new ObjectName(mBeanNames.uniqueName(name));
        } catch (Exception e) {
            throw new MetricsException(e);
        }
    }

    synchronized void removeObjectName(String name) {
        mBeanNames.map.remove(name);
    }

    synchronized void removeSource(String name) {
        sourceNames.map.remove(name);
    }

    synchronized String newSourceName(String name, boolean dupOK) {
        if (sourceNames.map.containsKey(name)) {
            if (dupOK) {
                return name;
            } else if (!miniClusterMode) {
                throw new MetricsException("Metrics source " + name + " already exists!");
            }
        }
        return sourceNames.uniqueName(name);
    }
}