#include <signal.h>
#include <errno.h>
#include <pthread.h>
#include <unistd.h>
#include <sys/types.h>
void sig_handler(int signum)
{
static int j = 0;
static int k = 0;
pthread_t sig_ppid = pthread_self();
// used to show which thread the signal is handled in.
if (signum == SIGUSR1) {
printf("thread %d, receive SIGUSR1 No. %d\n", sig_ppid, j);
j++;
//SIGRTMIN should not be considered constants from userland,
//there is compile error when use switch case
} else if (signum == SIGRTMIN) {
printf("thread %d, receive SIGRTMIN No. %d\n", sig_ppid, k);
k++;
}
}
void* worker_thread()
{
pthread_t ppid = pthread_self();
pthread_detach(ppid);
while (1) {
printf("I'm thread %d, I'm alive\n", ppid);
sleep(10);
}
}
void* sigmgr_thread()
{
sigset_t waitset, oset;
siginfo_t info;
int rc;
pthread_t ppid = pthread_self();
pthread_detach(ppid);
sigemptyset(&waitset);
sigaddset(&waitset, SIGRTMIN);
sigaddset(&waitset, SIGUSR1);
while (1) {
rc = sigwaitinfo(&waitset, &info);
if (rc != -1) {
printf("sigwaitinfo() fetch the signal - %d\n", rc);
sig_handler(info.si_signo);
} else {
printf("sigwaitinfo() returned err: %d; %s\n", errno, strerror(errno));
}
}
}
int main()
{
sigset_t bset, oset;
int i;
pid_t pid = getpid();
pthread_t ppid;
// Block SIGRTMIN and SIGUSR1 which will be handled in
//dedicated thread sigmgr_thread()
// Newly created threads will inherit the pthread mask from its creator
sigemptyset(&bset);
sigaddset(&bset, SIGRTMIN);
sigaddset(&bset, SIGUSR1);
if (pthread_sigmask(SIG_BLOCK, &bset, &oset) != 0)
printf("!! Set pthread mask failed\n");
// Create the dedicated thread sigmgr_thread() which will handle
// SIGUSR1 and SIGRTMIN synchronously
pthread_create(&ppid, NULL, sigmgr_thread, NULL);
// Create 5 worker threads, which will inherit the thread mask of
// the creator main thread
for (i = 0; i < 5; i++) {
pthread_create(&ppid, NULL, worker_thread, NULL);
}
// send out 50 SIGUSR1 and SIGRTMIN signals
for (i = 0; i < 50; i++) {
kill(pid, SIGUSR1);
printf("main thread, send SIGUSR1 No. %d\n", i);
kill(pid, SIGRTMIN);
printf("main thread, send SIGRTMIN No. %d\n", i);
sleep(10);
}
exit (0);
}