hadoop-hdfs-project/hadoop-hdfs-httpfs/src/main/java/org/apache/hadoop/lib/service/Instrumentation.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.lib.service;

import org.apache.hadoop.classification.InterfaceAudience;

import java.util.Map;

@InterfaceAudience.Private
public interface Instrumentation {

  public interface Cron {

    public Cron start();

    public Cron stop();
  }

  public interface Variable<T> {

    T getValue();
  }

  public Cron createCron();

  public void incr(String group, String name, long count);

  public void addCron(String group, String name, Cron cron);

  public void addVariable(String group, String name, Variable<?> variable);

  //sampling happens once a second
  public void addSampler(String group, String name, int samplingSize, Variable<Long> variable);

  public Map<String, Map<String, ?>> getSnapshot();

}