59   int errorcode = pthread_rwlock_init(rwlock, nullptr);  in RWMutexImpl()  local
60   (void)errorcode;  in RWMutexImpl()
61   assert(errorcode == 0);  in RWMutexImpl()
82   int errorcode = pthread_rwlock_rdlock(rwlock);  in reader_acquire()  local
83   return errorcode == 0;  in reader_acquire()
92   int errorcode = pthread_rwlock_unlock(rwlock);  in reader_release()  local
93   return errorcode == 0;  in reader_release()
102   int errorcode = pthread_rwlock_wrlock(rwlock);  in writer_acquire()  local
103   return errorcode == 0;  in writer_acquire()
112   int errorcode = pthread_rwlock_unlock(rwlock);  in writer_release()  local
113   return errorcode == 0;  in writer_release()