content: /*
   * 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 com.alibaba.metrics;
  
  
  /**
   * <pre>
   * A gauge metric is an instantaneous reading of a particular value. To instrument a queue's depth,
   * for example:
   *
   * final Queue&lt;String&gt; queue = new ConcurrentLinkedQueue&lt;String&gt;();
   * final Gauge&lt;Integer&gt; queueDepth = new Gauge&lt;Integer&gt;() {
   *     public Integer getValue() {
   *         return queue.size();
   *     }
   * };
   *
   * 一种实时数据的度量，反映的是瞬态的数据，不具有累加性。
   * 具体的实现由具体定义，例如，获取当前jvm的活跃线程数
   * </pre>
   *
   * @param <T> the type of the metric's value
   */
  public interface Gauge<T> extends Metric {
      /**
       * Returns the metric's current value.
       *
       * @return the metric's current value
       */
      T getValue();
  }
  