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.metric;
  
  import java.util.concurrent.TimeUnit;
  
  /**
   * a simple util class to calculate run time
   *
   * @author Cody (weiyue.wy@alibaba-inc.com)
   * @since 2.0.5
   */
  public class TimeTicker {
      private TimeUnit unit;
      private long start;
      private long end;
  
      public TimeTicker(TimeUnit unit) {
          if (unit != TimeUnit.NANOSECONDS && unit != TimeUnit.MILLISECONDS) {
              throw new IllegalArgumentException("invalid unit!");
          }
          this.unit = unit;
      }
  
      public TimeTicker(TimeUnit unit, boolean start) {
          this(unit);
          if (start) {
              start();
          }
      }
  
      public void start() {
          if (unit == TimeUnit.MILLISECONDS) {
              this.start = System.currentTimeMillis();
          } else if (unit == TimeUnit.NANOSECONDS) {
              this.start = System.nanoTime();
          }
      }
  
      public long stop() {
          if (unit == TimeUnit.MILLISECONDS) {
              this.end = System.currentTimeMillis();
          } else if (unit == TimeUnit.NANOSECONDS) {
              this.end = System.nanoTime();
          }
          return end - start;
      }
  
      public long stopAndRestart() {
          long elapsed = stop();
          start();
          return elapsed;
      }
  }
  