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 org.apache.hadoop.classification.InterfaceAudience;
022    import org.apache.hadoop.classification.InterfaceStability;
023    import org.apache.hadoop.metrics2.MetricsInfo;
024    import org.apache.hadoop.metrics2.MetricsRecordBuilder;
025    
026    /**
027     * A mutable long counter
028     */
029    @InterfaceAudience.Public
030    @InterfaceStability.Evolving
031    public class MutableCounterLong extends MutableCounter {
032    
033      private volatile long value;
034    
035      MutableCounterLong(MetricsInfo info, long initValue) {
036        super(info);
037        this.value = initValue;
038      }
039    
040      @Override
041      public synchronized void incr() {
042        ++value;
043        setChanged();
044      }
045    
046      /**
047       * Increment the value by a delta
048       * @param delta of the increment
049       */
050      public synchronized void incr(long delta) {
051        value += delta;
052        setChanged();
053      }
054    
055      public long value() {
056        return value;
057      }
058    
059      @Override
060      public void snapshot(MetricsRecordBuilder builder, boolean all) {
061        if (all || changed()) {
062          builder.addCounter(info(), value);
063          clearChanged();
064        }
065      }
066    
067    }