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 019package org.apache.hadoop.mapreduce; 020 021import org.apache.hadoop.classification.InterfaceAudience; 022import org.apache.hadoop.classification.InterfaceStability; 023import org.apache.hadoop.classification.InterfaceAudience.Private; 024import org.apache.hadoop.io.Writable; 025 026/** 027 * A named counter that tracks the progress of a map/reduce job. 028 * 029 * <p><code>Counters</code> represent global counters, defined either by the 030 * Map-Reduce framework or applications. Each <code>Counter</code> is named by 031 * an {@link Enum} and has a long for the value.</p> 032 * 033 * <p><code>Counters</code> are bunched into Groups, each comprising of 034 * counters from a particular <code>Enum</code> class. 035 */ 036@InterfaceAudience.Public 037@InterfaceStability.Stable 038public interface Counter extends Writable { 039 040 /** 041 * Set the display name of the counter 042 * @param displayName of the counter 043 * @deprecated (and no-op by default) 044 */ 045 @Deprecated 046 void setDisplayName(String displayName); 047 048 /** 049 * @return the name of the counter 050 */ 051 String getName(); 052 053 /** 054 * Get the display name of the counter. 055 * @return the user facing name of the counter 056 */ 057 String getDisplayName(); 058 059 /** 060 * What is the current value of this counter? 061 * @return the current value 062 */ 063 long getValue(); 064 065 /** 066 * Set this counter by the given value 067 * @param value the value to set 068 */ 069 void setValue(long value); 070 071 /** 072 * Increment this counter by the given value 073 * @param incr the value to increase this counter by 074 */ 075 void increment(long incr); 076 077 @Private 078 /** 079 * Return the underlying object if this is a facade. 080 * @return the undelying object. 081 */ 082 Counter getUnderlyingCounter(); 083}