pthread_mutex_lock(3)					     Library Functions Manual					     pthread_mutex_lock(3)

NAME

       pthread_mutex_lock - Locks an unlocked mutex.

LIBRARY

       DECthreads POSIX 1003.1c Library (libpthread.so)

SYNOPSIS

       #include <pthread.h>

       int   pthread_mutex_lock(
			      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  locks  a	mutex  with behavior that depends upon the type of mutex, as follows: If a normal or default mutex is specified, a
       deadlock can result if the current owner of the mutex calls this routine in an attempt to lock the mutex a second time.	(The  deadlock	is
       not  detected  or reported.)  If a recursive mutex is specified, the current owner of the mutex can relock the same mutex without blocking.
       The lock count is incremented for each recursive lock within the thread.  If an errorcheck mutex is specified and the current  owner  tries
       to  lock  the  mutex a second time, this routine reports the [EDEADLK] error.  If the mutex is locked by another thread, the calling thread
       waits for the mutex to become available.

       Use the pthread_mutexattr_settype(3) routine to set the type of the mutex to normal, default, recursive, or errorcheck. For  more  informa-
       tion about types of mutexes, see the desciption of pthread_mutexattr_settype(3).

       The  thread  that  has  locked a mutex becomes its current owner and remains its owner until the same thread has unlocked it.  This routine
       returns with the mutex in the locked state and with the current thread as the mutex's current owner.

       A recursive or errorcheck mutex records the identity of the thread that locks it, allowing debuggers to display this information.  In  most
       cases, normal and default mutexes do not record the owning thread's identity.

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.  A deadlock condition is detected.  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_trylock(3), pthread_mutex_unlock(3)

       Manuals: Guide to DECthreads and Programmer's Guide

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															     pthread_mutex_lock(3)