C++ timer example

C++ timer example · GitHub

#include <iostream> #include <set>

extern "C" { #include "unistd.h" #include <sys/timerfd.h> }

int main() { std::set<int> timerFds;

fd_set readfds; FD_ZERO(&readfds);

size_t n = 10; int maxFd = 0; for (size_t i = 1; i <= n; ++i) { int fd = timerfd_create(CLOCK_REALTIME, 0); maxFd = std::max(fd, maxFd);

itimerspec spec; spec.it_value = { (long)i, 0 }; spec.it_interval = { 0, 0 }; timerfd_settime(fd, 0, &spec, nullptr);

timerFds.emplace(fd); }

timespec timeout = { 2, 0 };

while (!timerFds.empty()) { for (const int& fd : timerFds) { FD_SET(fd, &readfds); }

int availableFds = pselect(maxFd + 1, &readfds, nullptr, nullptr, &timeout, nullptr); std::cout << "Available file descriptors: " << availableFds << std::endl;

if (availableFds > 0) { for (const int& fd : timerFds) { if (FD_ISSET(fd, &readfds)) { std::cout << "Found file descriptor: " << fd << std::endl;

int val; read(fd, &val, sizeof(val)); std::cout << "Read from file descriptor " << fd << ", value: " << val << std::endl;

itimerspec spec = { {0, 0}, {0, 0} }; timerfd_settime(fd, 0, &spec, nullptr); } } } else { break; } }

return 0; }