StopWatchSet.java

package arkref.ext.fig.basic;

import java.util.*;
import java.lang.ThreadLocal;

/**
 * 4/2/09: StopWatchSet should be re-entrant (can call begin("foo") twice) and thread-safe.
 */
public class StopWatchSet {
  // For measuring time of certain types of events.
  // Shared across all threads.
  private static Map<String, StopWatch> stopWatches = new LinkedHashMap<String, StopWatch>();

  // A stack of stop-watches (one per thread)
  private static ThreadLocal<LinkedList<Pair<String,StopWatch>>> lastStopWatches = new ThreadLocal() {
    protected LinkedList<Pair<String,StopWatch>> initialValue() { return new LinkedList(); }
  };

  public synchronized static StopWatch getWatch(String s) {
    return MapUtils.getMut(stopWatches, s, new StopWatch());
  }

  public static void begin(String s) {
    // Create a new stop watch for reentrance and thread safety
    lastStopWatches.get().addLast(new Pair(s, new StopWatch().start()));
  }
  public static void end() {
    Pair<String,StopWatch> pair = lastStopWatches.get().removeLast();
    pair.getSecond().stop();
    // Add it
    synchronized(stopWatches) {
      getWatch(pair.getFirst()).add(pair.getSecond());
    }
  }

  public synchronized static OrderedStringMap getStats() {
    OrderedStringMap map = new OrderedStringMap();
    for(String key : stopWatches.keySet()) {
      StopWatch watch = getWatch(key);
      map.put(key, watch + " (" + new StopWatch(watch.n == 0 ? 0 : watch.ms/watch.n) + " x " + watch.n + ")");
    }
    return map;
  }
}