The Linux Programming Interface

506 Chapter 23

Listing 23-7: POSIX timer notification using a thread function

–––––––––––––––––––––––––––––––––––––––––––––––––timers/ptmr_sigev_thread.c

#include <signal.h>

#include <time.h>

#include <pthread.h>

#include "curr_time.h" /* Declaration of currTime() */

#include "tlpi_hdr.h"

#include "itimerspec_from_str.h" /* Declares itimerspecFromStr() */

static pthread_mutex_t mtx = PTHREAD_MUTEX_INITIALIZER;

static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;

static int expireCnt = 0; /* Number of expirations of all timers */

static void /* Thread notification function */

qthreadFunc(union sigval sv)

{

timer_t *tidptr;

int s;

tidptr = sv.sival_ptr;

printf("[%s] Thread notify\n", currTime("%T"));

printf(" timer ID=%ld\n", (long) *tidptr);

printf(" timer_getoverrun()=%d\n", timer_getoverrun(*tidptr));

/* Increment counter variable shared with main thread and signal

condition variable to notify main thread of the change. */

s = pthread_mutex_lock(&mtx);

if (s != 0)

errExitEN(s, "pthread_mutex_lock");

expireCnt += 1 + timer_getoverrun(*tidptr);

s = pthread_mutex_unlock(&mtx);

if (s != 0)

errExitEN(s, "pthread_mutex_unlock");

w s = pthread_cond_signal(&cond);

if (s != 0)

errExitEN(s, "pthread_cond_signal");

}

int

main(int argc, char *argv[])

{

struct sigevent sev;

struct itimerspec ts;

timer_t *tidlist;

int s, j;