Thread: POSIX timers in c++

hello all,

I'm using POSIX timers in C++ application, using timer_create() this timer will raise a signal when timer expires and to Handle this I want to use signal handler function (which is in my class method).

To achieve this I need to make this class method as static method, now if I wanna use any attribute in class that should be static variable!!! Is there any alternative method to achieve this ????


Thanks in advance

You can store a pointer to your class in the sigevent structure, then access that pointer in the signal handler.

Code:

struct sigevent e;
e.sigev_value.sival_ptr = myClassPointer;
// ...

Then in your signal handler:

Code:

void MyClass::StaticHandler(int sig, siginfo_t *si, void *uc)
{
    MyClass* c = reinterpret_cast<MyClass*>(si−>si_value.sival_ptr);
    c->foo();
}

thanks to bithub for your answer.

I tried to solve the problem this way but I got some problems to set up the right signal handler function.

If I tried to set the extended handler function - all I got was this error:

Code:

void Scheduler::tic(int sigNumb, siginfo_t *si, void *uc) {
	perror("i was called");
}

this->SignalAction.sa_handler = Scheduler::tic;

error: invalid conversion from 'void (*)(int, siginfo_t*, void*)' to 'void (*)(int)'

Am I right in setting the handler to sa_handler ?

By the way... am I allowed to pass references to class members for setting up the timer, as follows:

Code:

timer_create(CLOCK_REALTIME, &this->signalEvent, &this->timerID)

thanks for your help

To use a signalhandler function with the signature

Code:

void func(int signo, siginfo_t *info, void *context)

The flag SA_SIGINFO has to be set in sigaction.sa_flags and the callback-function pointer has to be added to sigaction.sa_sigaction.

Code:

       struct sigevent signalEvent;
	
	struct sigaction SignalAction;

       // Define sigaction method
	this->SignalAction.sa_sigaction = Scheduler::tic;
	// set mask empty -> react on all signals
	sigemptyset(&this->SignalAction.sa_mask);
	this->SignalAction.sa_flags = SA_SIGINFO;

	// Define sigEvent
	this->signalEvent.sigev_value.sival_ptr = this;

This solved the problem mentioned in my previous post.