Try to Acquire a Read Lock

rw_tryrdlock(3T)

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

int rw_tryrdlock(rwlock_t *rwlp);

Use rw_tryrdlock() to attempt to acquire a read lock on the readers/writer lock pointed to by rwlp. When the readers/writer lock is already locked for writing, it returns an error. Otherwise, the read lock is acquired.

Return Values

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

EINVAL

Invalid argument.

EFAULT

rwlp points to an illegal address.

EBUSY

The readers/writer lock pointed to by rwlp was already locked.