/****************************************************************************/
/* Copyright (c) 2000 MBARI                                                 */
/* MBARI Proprietary Information. All rights reserved.                      */
/****************************************************************************/
/* Summary  :                                                               */
/* Filename : PeriodicTask.h                                                */
/* Author   :                                                               */
/* Project  :                                                               */
/* Version  : 1.0                                                           */
/* Created  : 02/07/2000                                                    */
/* Modified :                                                               */
/* Archived :                                                               */
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/* Modification History:                                                    */
/****************************************************************************/
#ifndef _PERIODICTASK_H
#define _PERIODICTASK_H

#include <time.h>
#include <signal.h>
#include "Task.h"
#include "DynamicArray.h"
#include "EventService.h"

/*
CLASS 
PeriodicTask

DESCRIPTION
PeriodicTask invokes callback method(s) at specified period(s)
Also contains an EventService object, allowing application to 
subscribe to events.

AUTHOR
Tom O'Reilly
*/

class PeriodicTask : public Task {

public:

  ///////////////////////////////////////////////////////////////////
  // Constructor
  // [input] name: Task name
  PeriodicTask(const char *name);

  virtual ~PeriodicTask();

  ///////////////////////////////////////////////////////////////////
  // Main process function
  virtual void run();

  ///////////////////////////////////////////////////////////////////
  // Log data at specified period
  virtual void log(int millisec);


protected:

  ///////////////////////////////////////////////////////////////////
  // Prototype for callback methods
  typedef void (PeriodicTask::*CallbackMethod)();

  ///////////////////////////////////////////////////////////////////
  // Register a callback function for given sampling period
  // [input] millisec: Period at which to invoke callback
  // [input] callback: callback function
  void addPeriodicCallback(unsigned int millisec, CallbackMethod callback);

  ///////////////////////////////////////////////////////////////////
  // Called just before start of sampling loop
  virtual void startSampling();

  ///////////////////////////////////////////////////////////////////
  // Set timer
  void setTimer();

  ///////////////////////////////////////////////////////////////////
  // EventService object
  EventService *_eventService;


private:

  // Invoke registered callbacks 
  int invokePeriodicCallbacks();

  // Compute sample loop frequency
  void computeSampleInterval();

  // Fill in _delay timeval struct
  void computeDelay();

  // Period of timing loop
  int _sampleInterval;

  // Greatest period requested
  int _maxInterval;

  // Interval accumulated so far before start of next cycle
  int _accumulatedInterval;


  struct CallbackObj
  {
    CallbackObj(CallbackMethod callback) {
      _callback = callback;
    }

    CallbackMethod _callback;
  };


  struct CallbackList
  {
    int sampleInterval;

    // Callbacks to be called at this rate
    DynamicArray<CallbackObj *> callbacks;
  };

  DynamicArray<CallbackList *> _callbackLists;

  struct timespec _delay;


  ///////////////////////////////////////////////////////////////////
  // Called when timer expires; sets _timerExpired to True
  static void alarmSignalHandler(int signalNo);

  // Use this to decide when to invoke periodic callback(s)
  static Boolean _timerExpired;

  timer_t _timer;
};


#endif