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.jstorm.common.metric.old;
  
  import java.io.Closeable;
  import java.util.concurrent.Callable;
  import java.util.concurrent.TimeUnit;
  
  /**
   * Use com.codahale.metrics's interface
   * 
   * @author zhongyan.feng
   * 
   */
  public class Timer extends Histogram {
      private static final long serialVersionUID = 5915881891513771108L;
  
      /**
       * A timing context.
       * 
       * @see Timer#time()
       */
      public static class Context implements Closeable {
          private final Timer timer;
          private final long startTime;
  
          private Context(Timer timer) {
              this.timer = timer;
              this.startTime = System.currentTimeMillis();
          }
  
          /**
           * Stops recording the elapsed time, updates the timer and returns the elapsed time in nanoseconds.
           */
          public long stop() {
              final long elapsed = System.currentTimeMillis() - startTime;
              timer.update(elapsed, TimeUnit.MILLISECONDS);
              return elapsed;
          }
  
          @Override
          public void close() {
              stop();
          }
      }
  
      public Timer() {
          init();
      }
  
      /**
       * Adds a recorded duration.
       * 
       * @param duration the length of the duration
       * @param unit the scale unit of {@code duration}
       */
      public void update(long duration, TimeUnit unit) {
          update(unit.toMillis(duration));
      }
  
      /**
       * Times and records the duration of event.
       * 
       * @param event a {@link Callable} whose {@link Callable#call()} method implements a process whose duration should be timed
       * @param <T> the type of the value returned by {@code event}
       * @return the value returned by {@code event}
       * @throws Exception if {@code event} throws an {@link Exception}
       */
      public <T> T time(Callable<T> event) throws Exception {
          final long startTime = System.currentTimeMillis();
          try {
              return event.call();
          } finally {
              update(System.currentTimeMillis() - startTime);
          }
      }
  
      /**
       * Returns a new {@link Context}.
       * 
       * @return a new {@link Context}
       * @see Context
       */
      public Context time() {
          return new Context(this);
      }
  
      public long getCount() {
          return allWindow.getSnapshot().getTimes();
      }
  }
  