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;
020
021import java.util.Collection;
022
023import org.apache.hadoop.classification.InterfaceAudience;
024import org.apache.hadoop.classification.InterfaceStability;
025
026/**
027 * An immutable snapshot of metrics with a timestamp
028 */
029@InterfaceAudience.Public
030@InterfaceStability.Evolving
031public interface MetricsRecord {
032  /**
033   * Get the timestamp of the metrics
034   * @return  the timestamp
035   */
036  long timestamp();
037
038  /**
039   * @return the metrics record name
040   */
041  String name();
042
043  /**
044   * @return the description of the metrics record
045   */
046  String description();
047
048  /**
049   * @return the context name of the metrics record
050   */
051  String context();
052
053  /**
054   * Get the tags of the record
055   * Note: returning a collection instead of iterable as we
056   * need to use tags as keys (hence Collection#hashCode etc.) in maps
057   * @return an unmodifiable collection of tags
058   */
059  Collection<MetricsTag> tags();
060
061  /**
062   * Get the metrics of the record
063   * @return an immutable iterable interface for metrics
064   */
065  Iterable<AbstractMetric> metrics();
066}