it.tidalwave.stopwatch.StopWatch Maven / Gradle / Ivy

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/*
 * #%L
 * *********************************************************************************************************************
 * 
 * These Foolish Things - Miscellaneous utilities
 * http://thesefoolishthings.java.net - hg clone https://bitbucket.org/tidalwave/thesefoolishthings-src
 * %%
 * Copyright (C) 2009 - 2013 Tidalwave s.a.s. (http://tidalwave.it)
 * %%
 * *********************************************************************************************************************
 * 
 * Licensed 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.
 * 
 * *********************************************************************************************************************
 * 
 * $Id: StopWatch.java,v e7e97a14be7c 2013/02/16 19:44:07 fabrizio $
 * 
 * *********************************************************************************************************************
 * #L%
 */
package it.tidalwave.stopwatch;

import java.util.Stack;

/***********************************************************************************************************************
 *
 * @author  Fabrizio Giudici
 * @version $Id: StopWatch.java,v e7e97a14be7c 2013/02/16 19:44:07 fabrizio $
 * @experimental
 *
 **********************************************************************************************************************/
public class StopWatch
  {
    private StopWatchStats stats;
    private long startTime;
    private long partialStartTime;
    private long accumulated;

    private final static ThreadLocal> stack = new ThreadLocal>()
      {
        @Override
        protected Stack initialValue()
          {
            return new Stack();
          }
      };

    public static final StopWatch DUMMY_STOPWATCH = new StopWatch()
      {
        @Override
        public void cancel()
          {
          }

        @Override
        public void stop()
          {
          }
      };

    public static StopWatch create (final Class clazz, final String name)
      {
        return new StopWatch(clazz, name);
      }

    protected StopWatch()
      {
        partialStartTime = 0;
      }

    protected StopWatch (final Class clazz, final String name)
      {
        final String baseName = clazz.getName().replace('.', '/') + "/" + name;
        // Create here the reference to stats, in order to avoid overhead in stop()
        stats = StopWatchStats.find(baseName);
        final Stack currentStack = stack.get();

        if (!currentStack.isEmpty())
          {
            currentStack.peek().suspend();
          }

        currentStack.push(this);
        startTime = partialStartTime = System.nanoTime();
      }

    public void stop()
      {
        final long now = System.nanoTime();
        stats.addTimeSample(now - partialStartTime + accumulated, now - startTime);
        cancel();
      }

    public void cancel()
      {
        stats = null;
        final Stack currentStack = stack.get();
        currentStack.pop();

        if (!currentStack.isEmpty())
          {
            currentStack.peek().resume();
          }
      }

    protected void suspend()
      {
        accumulated += System.nanoTime() - partialStartTime;
      }

    protected void resume()
      {
        partialStartTime = System.nanoTime();
      }
  }