Professional Multicore Programming: Design and Implementation for C++ Developers

Name

NAME

pthread_cond_broadcast, pthread_cond_signal — broadcast or signal a condition

SYNOPSIS

THR #include <pthread.h>

    int pthread_cond_broadcast(pthread_cond_t *cond);
    int pthread_cond_signal(pthread_cond_t *cond);

DESCRIPTION

These functions shall unblock threads blocked on a condition variable.

The pthread_cond_broadcast() function shall unblock all threads currently blocked on the specified condition variable cond.

The pthread_cond_signal() function shall unblock at least one of the threads that are blocked on the specified condition variable cond (if any threads are blocked on cond).

If more than one thread is blocked on a condition variable, the scheduling policy shall determine the order in which threads are unblocked. When each thread unblocked as a result of a pthread_cond_broadcast() or pthread_cond_signal() returns from its call to pthread_cond_wait() or pthread_cond_timedwait(), the thread shall own the mutex with which it called pthread_cond_wait() or pthread_cond_timedwait(). The thread(s) that are unblocked shall contend for the mutex according to the scheduling policy (if applicable), and as if each had called pthread_mutex_lock().

The pthread_cond_broadcast() or pthread_cond_signal() functions may be called by a thread whether or not it currently owns the mutex that threads calling pthread_cond_wait() or pthread_cond_timedwait() have associated with the condition variable during their waits; however, if predictable scheduling behavior is required, then that mutex shall ...