NestedMonitor.java

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package etm.core.monitor;

import etm.core.aggregation.Aggregator;
import etm.core.timer.ExecutionTimer;

/**
 * <p/>
 * The NestedMonitor records nested EtmPoints as a tree using ThreadLocals
 * to maintain the thread depend caller tree.
 * </p>
 * <p/>
 * Be aware that leaking EtmPoints will lead to unexpected results - so
 * always ensure you call EtmPoint.collect() in a finally clause.
 * </p>
 *
 * @author Jens Schumann
 * @version $Revision$
 */
public class NestedMonitor extends EtmMonitorSupport {

  private static final String DESCRIPTION = "A monitor recording nested executions as a tree.";
  private ThreadLocal currentParent = new ThreadLocal();

  public NestedMonitor() {
    this(null, null);
  }

  public NestedMonitor(ExecutionTimer aTimer) {
    this(aTimer, null);
  }

  public NestedMonitor(Aggregator aAggregator) {
    this(null, aAggregator);
  }

  public NestedMonitor(ExecutionTimer aTimer, Aggregator aAggregator) {
    super(DESCRIPTION, aTimer, aAggregator);
  }

  protected void doVisitPreMeasurement(MeasurementPoint measurementPoint) {
    MeasurementPoint point = (MeasurementPoint) currentParent.get();
    currentParent.set(measurementPoint);
    measurementPoint.setParent(point);
  }

  protected void doVisitPostCollect(MeasurementPoint aPoint) {
    EtmPoint point = (EtmPoint) currentParent.get();
    if (point != null) {
      currentParent.set(point.getParent());
    }
  }

  public String toString() {
    return "etm.core.monitor.NestedMonitor{ timer=<" + timer + ">, aggregator=<" + aggregator + "> }";
  }

}