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 */ 018package org.apache.hadoop.hbase.metrics; 019 020import org.apache.hadoop.hbase.HBaseInterfaceAudience; 021import org.apache.yetus.audience.InterfaceAudience; 022import org.apache.yetus.audience.InterfaceStability; 023 024/** 025 * A mutable number optimized for high concurrency counting. 026 */ 027@InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.COPROC) 028@InterfaceStability.Evolving 029public interface Counter extends Metric { 030 031 /** 032 * Increment {@code this} by 1. 033 */ 034 void increment(); 035 036 /** 037 * Increment {@code this} by {@code n}. 038 * @param n The amount to increment. 039 */ 040 void increment(long n); 041 042 /** 043 * Decrement {@code this} by 1. 044 */ 045 void decrement(); 046 047 /** 048 * Decrement {@code this} by {@code n}. 049 * @param n The amount to decrement. 050 */ 051 void decrement(long n); 052 053 /** 054 * Returns the current value. 055 * @return the current value. 056 */ 057 long getCount(); 058}