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.annotation;
020    
021    import java.lang.annotation.*;
022    
023    import org.apache.hadoop.classification.InterfaceAudience;
024    import org.apache.hadoop.classification.InterfaceStability;
025    
026    /**
027     * Annotation interface for a group of metrics
028     */
029    @InterfaceAudience.Public
030    @InterfaceStability.Evolving
031    @Documented
032    @Target({ElementType.TYPE})
033    @Retention(RetentionPolicy.RUNTIME)
034    public @interface Metrics {
035    
036      /**
037       * @return the (record) name of the metrics
038       */
039      String name() default "";
040    
041      /**
042       * @return the optional description of metrics
043       */
044      String about() default "";
045    
046      /**
047       * @return the context name for a group of metrics
048       */
049      String context();
050    }