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    
019    package org.apache.hadoop.metrics2;
020    
021    import java.util.Collection;
022    
023    import org.apache.hadoop.classification.InterfaceAudience;
024    import org.apache.hadoop.classification.InterfaceStability;
025    
026    /**
027     * An immutable snapshot of metrics with a timestamp
028     */
029    @InterfaceAudience.Public
030    @InterfaceStability.Evolving
031    public interface MetricsRecord {
032      /**
033       * Get the timestamp of the metrics
034       * @return  the timestamp
035       */
036      long timestamp();
037    
038      /**
039       * @return the record name
040       */
041      String name();
042    
043      /**
044       * @return the description of the record
045       */
046      String description();
047    
048      /**
049       * @return the context name of the 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    }