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 standards 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 argument.  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 routine, 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 by  the  calling  thread.
       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 attribute (normal, default, recursive, or errorcheck).

RETURN VALUES

       If an error condition occurs, this routine returns an integer value indicating 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 not a valid mutex.

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

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															  pthread_mutex_trylock(3)