ChronoTrigger

ChronoTrigger is a simple, restartable timer. It is written in C++11 and depends only on its STL headers. Total LoC is 80 lines:

-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
C++                              1             25             27             51
C/C++ Header                     1             13              9             29
-------------------------------------------------------------------------------
SUM:                             2             38             36             80
-------------------------------------------------------------------------------

API

void setCallback(std::function<void(int)> cb, uint32_t data);
bool start(uint32_t interval, bool single = false);
void restart();
void finish();
void stop();

Building

ChronoTrigger can be used as plain source in a project after including the chronotrigger.h header file and adding the chronotrigger.cpp source file to the project. Alternatively a library can be built using the provided Makefile in the src folder:

make lib

This will build the .a library in the src/lib folder.

Only dependency is C++11.

Test application

A test application is found in the src/cpp-test folder, which can be built using the same Makefile in the src folder with the following command:

make test

The source for this test application looks as follows:

#include "../cpp/chronotrigger.h"

#include <iostream>
#include <atomic>


// Globals:
std::mutex mutex;
std::condition_variable cv;
std::atomic_uint8_t countdown;


void lavos(int value) {
	std::cout << "Lavos called with value: " << value << ". Countdown: " << (int) countdown.load() << std::endl;
	--countdown;
	if (countdown == 0) {
		cv.notify_all();
	}
}


int main() {
	// Have the timer class call the callback 10 times in 1 second intervals before the callback
	// ends the application.

	ChronoTrigger ct;
	countdown = 10;

	int keepAlive = 1; // In seconds.
	ct.setCallback(lavos, 42);
	ct.start((keepAlive) * 1000);

	// Wait until signalled.
	std::unique_lock<std::mutex> lk(mutex);
	cv.wait(lk);

	ct.stop();

	std::cout << "All done here." << std::endl;
	
	return 0;
}

Status

ChronoTrigger has been tested and so far found to be stable. More testing is however required for different usage scenarios.

This code is used in the NymphMQTT MQTT library, which is a component of the MQTTCute MQTT desktop client.