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pthread_mutex_trylock(3) Library Functions Manual pthread_mutex_trylock(3) NAME pthread_mutex_trylock - Attempts to lock the specified mutex, without waiting if already locked. LIBRARY DECthreads POSIX 1003.1c Library (libpthread.so) SYNOPSIS #include <pthread.h> int pthread_mutex_trylock( pthread_mutex_t *mutex); STANDARDS Interfaces documented on this reference page conform to industry stan- dards as follows: IEEE Std 1003.1c-1995, POSIX System Application Program Interface PARAMETERS Mutex to be locked. DESCRIPTION This routine attempts to lock the mutex specified in the mutex argu- ment. When a thread calls this routine, an attempt is made to immedi- ately lock the mutex. If the mutex is successfully locked, this routine returns zero (0) and the calling thread becomes the mutex's current owner. If the specified mutex is locked when a thread calls this rou- tine, the calling thread does not wait for the mutex to become avail- able. The behavior of this routine is as follows: For a normal, default, or errorcheck mutex: if the mutex is locked by any thread (including the calling thread) when this routine is called, this routine returns [EBUSY] and the calling thread does not wait to acquire the lock. For a normal or errorcheck mutex: if the mutex is not owned, this routine returns zero (0) and the mutex becomes locked. For a recursive mutex: if the mutex is owned by the calling thread, this routine returns zero (0) and the mutex lock count is incremented. (To unlock a recursive mutex, each call to pthread_mutex_trylock(3) must be matched by a call to pthread_mutex_unlock(3).) Use the pthread_mutexattr_settype(3) routine to set the mutex type at- tribute (normal, default, recursive, or errorcheck). RETURN VALUES If an error condition occurs, this routine returns an integer value in- dicating the type of error. Possible return values are as follows: Successful completion. The mutex is already locked; therefore, it was not acquired. The value specified by mutex is invalid, or The mutex was created with the protocol attribute set to PTHREAD_PRIO_PROTECT and the calling thread's priority set higher than the mutex's current pri- ority ceiling. ERRORS None RELATED INFORMATION Functions: pthread_mutexattr_settype(3), pthread_mutex_destroy(3), pthread_mutex_init(3), pthread_mutex_lock(3), pthread_mutex_unlock(3) Manuals: Guide to DECthreads and Programmer's Guide delim off pthread_mutex_trylock(3)