Multithreaded Programming Guide


#include <synch.h>  (or #include <thread.h>)

int rw_tryrdlock(rwlock_t *rwlp);

Use rw_tryrdlock(3THR) to attempt to acquire a read lock on the read-write lock pointed to by rwlp. When the read-write lock is already locked for writing, it returns an error. Otherwise, the read lock is acquired. (For POSIX threads, see "pthread_rwlock_tryrdlock(3THR)".)

Return Values

rw_tryrdlock() returns zero after completing successfully. Any other returned value indicates that an error occurred. When any of the following conditions occurs, the function fails and returns the corresponding value.


Invalid argument.


rwlp points to an illegal address.


The read-write lock pointed to by rwlp was already locked.