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.lib.service;
020
021import org.apache.hadoop.classification.InterfaceAudience;
022
023import java.util.Map;
024
025@InterfaceAudience.Private
026public interface Instrumentation {
027
028  public interface Cron {
029
030    public Cron start();
031
032    public Cron stop();
033  }
034
035  public interface Variable<T> {
036
037    T getValue();
038  }
039
040  public Cron createCron();
041
042  public void incr(String group, String name, long count);
043
044  public void addCron(String group, String name, Cron cron);
045
046  public void addVariable(String group, String name, Variable<?> variable);
047
048  //sampling happens once a second
049  public void addSampler(String group, String name, int samplingSize, Variable<Long> variable);
050
051  public Map<String, Map<String, ?>> getSnapshot();
052
053}