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pthread_mutex_trylock(3)
NAME
  pthread_mutex_trylock - Attempts to lock the specified mutex, without
  waiting if already locked

SYNOPSIS
  #include <pthread.h>

  int pthread_mutex_trylock(
	  pthread_mutex_t *mutex );

LIBRARY
  DECthreads POSIX 1003.1c Library (libpthread.so)

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
      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 immediately 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 available.

  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:

  0   Successful completion.

  [EBUSY]
      The mutex is already locked; therefore, it was not acquired.

  [EINVAL]
      The value specified by mutex is not a valid mutex.

ERRORS
  None

SEE ALSO
  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

Index for Section 3

Alphabetical listing for P

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