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.metrics2.lib; 020 021import org.apache.hadoop.classification.InterfaceAudience; 022import org.apache.hadoop.classification.InterfaceStability; 023import org.apache.hadoop.metrics2.MetricsRecordBuilder; 024 025/** 026 * The mutable metric interface 027 */ 028@InterfaceAudience.Public 029@InterfaceStability.Evolving 030public abstract class MutableMetric { 031 private volatile boolean changed = true; 032 033 /** 034 * Get a snapshot of the metric 035 * @param builder the metrics record builder 036 * @param all if true, snapshot unchanged metrics as well 037 */ 038 public abstract void snapshot(MetricsRecordBuilder builder, boolean all); 039 040 /** 041 * Get a snapshot of metric if changed 042 * @param builder the metrics record builder 043 */ 044 public void snapshot(MetricsRecordBuilder builder) { 045 snapshot(builder, false); 046 } 047 048 /** 049 * Set the changed flag in mutable operations 050 */ 051 protected void setChanged() { changed = true; } 052 053 /** 054 * Clear the changed flag in the snapshot operations 055 */ 056 protected void clearChanged() { changed = false; } 057 058 /** 059 * @return true if metric is changed since last snapshot/snapshot 060 */ 061 public boolean changed() { return changed; } 062}