CDP Studio Documentation

Framework - CDP Core
OSAPIPeriodicTimer
4.12.9

OSAPIPeriodicTimer Class

The OSAPIPeriodicTimer is a high-resolution timer for periodic thread scheduling. More...

Header:	#include <OSAPI/Timer/Timer.h>
Inherited By:	OSAPIOneShotTimer

List of all members, including inherited members

Public Functions

	OSAPIPeriodicTimer()
virtual	~OSAPIPeriodicTimer()
void	Destroy()
int	SetEvent()
virtual int	Start(int periodInMs)
virtual void	Stop()
int	WaitForEvent()

Detailed Description

The OSAPIPeriodicTimer is a high-resolution timer for periodic thread scheduling.

The WaitForEvent() method will wait for either a timer event or an event caused by a call to SetEvent().

Note that the timer will not catch up on missed events. This means that if we start the timer with a period set to 100ms, waiting 550 ms before executing WaitForEvent will make the function return immedeatly the first time and then continue its periods.

time      ----|---|---|---|---|---|---|---|---|---|---|---
event     ----*---*---*---*-----*-*---*---------*-*---*---

Usage

// In some thread's Main()
threadTimer.Start(PeriodInMS);
// ...

while(!Stopped())
{
  // Wait for timer tick or message event, set timerevent if timer event
  int event = threadTimer.WaitForEvent()
  if (event==0)
  {
    // Handle timer event
  }
  else if (event==1)
  {
    // Handle event caused by SetEvent()
  }
  else
  {
    // New events may be added in the future..
  }
}
threadTimer.Stop(); //

Member Function Documentation

OSAPIPeriodicTimer::OSAPIPeriodicTimer()

Constructs an OSAPIPeriodicTimer.

`[virtual]` OSAPIPeriodicTimer::~OSAPIPeriodicTimer()

Destructs the timer.

void OSAPIPeriodicTimer::Destroy()

Stops the timer and releases allocated resources.

int OSAPIPeriodicTimer::SetEvent()

Releases WaitForEvent() by signaling the event object.

Returns 0 on failure.

`[virtual]` int OSAPIPeriodicTimer::Start(int periodInMs)

Starts the timer.

periodInMs - Timer period in ms.

Returns: Event handle != 0 on success.

`[virtual]` void OSAPIPeriodicTimer::Stop()

Stops the timer.

int OSAPIPeriodicTimer::WaitForEvent()

Waits for timer event or event set by SetEvent().

Blocks calling thread until timer event or semaphore event occurs.

Returns 1 if event occured, 0 if timer tick occured. Supposed to return 0 if both event and timer tick occured.

Dependent implementation

WINDOWS: Uses timer functions SetWaitableTimer() / WaitForMultipleObjects();
Linux: Uses Mutex and timed condition variable (OSAPIEvent)

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