pthread_cond_signal

Wakes one thread that is waiting on a condition variable.

Syntax

pthread_cond_signal( cond );

Argument Data Type Access

cond opaque pthread_cond_t read

C Binding

int
pthread_cond_signal (
pthread_cond_t *cond);

Arguments

cond: Condition variable signaled.

Description

This routine wakes one thread waiting on a condition variable. Calling this routine implies that data guarded by the associated mutex has changed so that it might be possible for a single waiting thread to proceed. Call this routine when any thread waiting on the specified condition variable might find its predicate true, but only one thread should proceed.

The scheduling policy determines which thread is awakened. For policies SCHED_FIFO and SCHED_RR, a blocked thread is chosen in priority order, using first-in/first-out (FIFO) within priorities.

You can call this routine regardless if the associated mutex is locked.

Return Values

If an error condition occurs, this routine returns -1 and sets errno to the corresponding error value. Possible return values are as follows:

Return Error Description

0 Successful completion. -1 [EINVAL] The value specified by cond is invalid.