private boolean canPurge(MonitoredTask stat) {
    long cts = stat.getCompletionTimestamp();
    return (cts > 0 && EnvironmentEdgeManager.currentTime() - cts > expirationTime);
  }
Create a task filter according to a given filter type.
@param filter type of monitored task
@return a task filter
hbase-server/src/main/java/org/apache/hadoop/hbase/monitoring/TaskMonitor.java