cnd_signal
From cppreference.com
                    
                                        
                    
                    
                                                            
                    | Defined in header  <threads.h> | ||
| int cnd_signal( cnd_t *cond ); | (since C11) | |
Unblocks one thread that currently waits on condition variable pointed to by cond. If no threads are blocked, does nothing and returns thrd_success.
[edit] Parameters
| cond | - | pointer to a condition variable | 
[edit] Return value
thrd_success if successful, thrd_error otherwise.
[edit] See also
| (C11) | unblocks all threads blocked on a condition variable (function) |