Attempt to lock this reader-writer mutex for reading. Immediately return 0 on success, and a non-zero value if there are active or pending writers. If successful, unlockRead or unlock must be used to release the lock on this mutex. The behavior is undefined if this method is called from a thread that already has a lock on this mutex.
Declared in <bslmt_readerwritermutex.h>
int
tryLockRead();