code: public void completed(TaskAttemptID taskid) {
      //
      // Record that this taskid is complete
      //
      completedTask(taskid, TaskStatus.State.SUCCEEDED);
          
      // Note the successful taskid
      setSuccessfulTaskid(taskid);
      
      //
      // Now that the TIP is complete, the other speculative 
      // subtasks will be closed when the owning tasktracker 
      // reports in and calls shouldClose() on this object.
      //
  
      this.completes++;
      this.execFinishTime = JobTracker.getClock().getTime();
      recomputeProgress();
      
    }
docs: Indicate that one of the taskids in this TaskInProgress
  has successfully completed!