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 org.apache.activemq.util;
  
  /**
   * A very simple stop watch.
   * <p/>
   * This implementation is not thread safe and can only time one task at any given time.
   */
  public final class StopWatch {
  
      private long start;
      private long stop;
  
      /**
       * Starts the stop watch
       */
      public StopWatch() {
          this(true);
      }
  
      /**
       * Creates the stop watch
       *
       * @param started whether it should start immediately
       */
      public StopWatch(boolean started) {
          if (started) {
              restart();
          }
      }
  
      /**
       * Starts or restarts the stop watch
       */
      public void restart() {
          start = System.currentTimeMillis();
          stop = 0;
      }
  
      /**
       * Stops the stop watch
       *
       * @return the time taken in milliseconds.
       */
      public long stop() {
          stop = System.currentTimeMillis();
          return taken();
      }
  
      /**
       * Returns the time taken in milliseconds.
       *
       * @return time in milliseconds
       */
      public long taken() {
          if (start > 0 && stop > 0) {
              return stop - start;
          } else if (start > 0) {
              return System.currentTimeMillis() - start;
          } else {
              return 0;
          }
      }
  }
  