001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one
003     * or more contributor license agreements.  See the NOTICE file
004     * distributed with this work for additional information
005     * regarding copyright ownership.  The ASF licenses this file
006     * to you under the Apache License, Version 2.0 (the
007     * "License"); you may not use this file except in compliance
008     * with the License.  You may obtain a copy of the License at
009     *
010     *     http://www.apache.org/licenses/LICENSE-2.0
011     *
012     * Unless required by applicable law or agreed to in writing, software
013     * distributed under the License is distributed on an "AS IS" BASIS,
014     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package org.apache.hadoop.metrics2.lib;
020    
021    import java.util.concurrent.atomic.AtomicReference;
022    import javax.management.ObjectName;
023    
024    import org.apache.hadoop.classification.InterfaceAudience;
025    import org.apache.hadoop.classification.InterfaceStability;
026    import org.apache.hadoop.metrics2.MetricsException;
027    import org.apache.hadoop.metrics2.MetricsSystem;
028    import org.apache.hadoop.metrics2.impl.MetricsSystemImpl;
029    
030    /**
031     * The default metrics system singleton
032     */
033    @InterfaceAudience.Public
034    @InterfaceStability.Evolving
035    public enum DefaultMetricsSystem {
036      INSTANCE; // the singleton
037    
038      private AtomicReference<MetricsSystem> impl =
039          new AtomicReference<MetricsSystem>(new MetricsSystemImpl());
040      volatile boolean miniClusterMode = false;
041      transient final UniqueNames mBeanNames = new UniqueNames();
042      transient final UniqueNames sourceNames = new UniqueNames();
043    
044      /**
045       * Convenience method to initialize the metrics system
046       * @param prefix  for the metrics system configuration
047       * @return the metrics system instance
048       */
049      public static MetricsSystem initialize(String prefix) {
050        return INSTANCE.init(prefix);
051      }
052    
053      MetricsSystem init(String prefix) {
054        return impl.get().init(prefix);
055      }
056    
057      /**
058       * @return the metrics system object
059       */
060      public static MetricsSystem instance() {
061        return INSTANCE.getImpl();
062      }
063    
064      /**
065       * Shutdown the metrics system
066       */
067      public static void shutdown() {
068        INSTANCE.shutdownInstance();
069      }
070    
071      void shutdownInstance() {
072        boolean last = impl.get().shutdown();
073        if (last) synchronized(this) {
074          mBeanNames.map.clear();
075          sourceNames.map.clear();
076        }
077      }
078    
079      @InterfaceAudience.Private
080      public static MetricsSystem setInstance(MetricsSystem ms) {
081        return INSTANCE.setImpl(ms);
082      }
083    
084      MetricsSystem setImpl(MetricsSystem ms) {
085        return impl.getAndSet(ms);
086      }
087    
088      MetricsSystem getImpl() { return impl.get(); }
089    
090      @InterfaceAudience.Private
091      public static void setMiniClusterMode(boolean choice) {
092        INSTANCE.miniClusterMode = choice;
093      }
094    
095      @InterfaceAudience.Private
096      public static boolean inMiniClusterMode() {
097        return INSTANCE.miniClusterMode;
098      }
099    
100      @InterfaceAudience.Private
101      public static ObjectName newMBeanName(String name) {
102        return INSTANCE.newObjectName(name);
103      }
104    
105      @InterfaceAudience.Private
106      public static void removeMBeanName(ObjectName name) {
107        INSTANCE.removeObjectName(name.toString());
108      }
109    
110      @InterfaceAudience.Private
111      public static String sourceName(String name, boolean dupOK) {
112        return INSTANCE.newSourceName(name, dupOK);
113      }
114    
115      synchronized ObjectName newObjectName(String name) {
116        try {
117          if (mBeanNames.map.containsKey(name) && !miniClusterMode) {
118            throw new MetricsException(name +" already exists!");
119          }
120          return new ObjectName(mBeanNames.uniqueName(name));
121        } catch (Exception e) {
122          throw new MetricsException(e);
123        }
124      }
125    
126      synchronized void removeObjectName(String name) {
127        mBeanNames.map.remove(name);
128      }
129    
130      synchronized String newSourceName(String name, boolean dupOK) {
131        if (sourceNames.map.containsKey(name)) {
132          if (dupOK) {
133            return name;
134          } else if (!miniClusterMode) {
135            throw new MetricsException("Metrics source "+ name +" already exists!");
136          }
137        }
138        return sourceNames.uniqueName(name);
139      }
140    }