Signals on the condition variable.
#include <pthread.h>
int pthread_cond_signal (
pthread_cond_t *cond);
(IN) Points to the condition variable to signal.
If successful, returns zero; otherwise, returns a nonzero error code:
The pthread_cond_signal function wakes up one of the threads blocked on the condition variable. If more than one thread is blocked on the condition variable, no assumptions can be made on which of those threads might be awakened. The pthread_cond_signal function has no effect on threads that are not awakened.
NOTE:Condition variables are stateless. If no threads are blocked on the condition variable, the call to pthread_cond_signal has no effect and is not remembered. A subsequent call to pthread_cond_wait or pthread_cond_timedwait blocks the calling thread.