NAME

       pthread_spin_destroy,  pthread_spin_init  -  destroy  or initialize a spin lock object (ADVANCED REALTIME
       THREADS)

SYNOPSIS

       #include <pthread.h>

       int pthread_spin_destroy(pthread_spinlock_t *lock);
       int pthread_spin_init(pthread_spinlock_t *lock, int pshared);

DESCRIPTION

       The pthread_spin_destroy() function shall destroy the spin  lock  referenced  by  lock  and  release  any
       resources  used  by  the  lock.  The  effect of subsequent use of the lock is undefined until the lock is
       reinitialized by another call to pthread_spin_init(). The results are undefined if pthread_spin_destroy()
       is called when a thread holds the lock, or if this function is called with an uninitialized  thread  spin
       lock.

       The pthread_spin_init() function shall allocate any resources required to use the spin lock referenced by
       lock and initialize the lock to an unlocked state.

       If  the  Thread  Process-Shared  Synchronization  option  is  supported  and  the  value  of  pshared  is
       PTHREAD_PROCESS_SHARED, the implementation shall permit the spin lock to be operated upon by  any  thread
       that has access to the memory where the spin lock is allocated, even if it is allocated in memory that is
       shared by multiple processes.

       If  the  Thread  Process-Shared  Synchronization  option  is  supported  and  the  value  of  pshared  is
       PTHREAD_PROCESS_PRIVATE, or if the option is not supported, the spin lock shall only be operated upon  by
       threads  created  within  the  same  process  as the thread that initialized the spin lock. If threads of
       differing processes attempt to operate on such a spin lock, the behavior is undefined.

       The results are undefined if pthread_spin_init() is called specifying an already initialized  spin  lock.
       The results are undefined if a spin lock is used without first being initialized.

       If  the  pthread_spin_init()  function  fails,  the  lock is not initialized and the contents of lock are
       undefined.

       Only the object referenced by lock may be used for performing synchronization.

       The result of referring to copies of that object in calls to pthread_spin_destroy(), pthread_spin_lock(),
       pthread_spin_trylock(), or pthread_spin_unlock() is undefined.

RETURN VALUE

       Upon successful completion, these functions shall return  zero;  otherwise,  an  error  number  shall  be
       returned to indicate the error.

ERRORS

       These functions may fail if:

       EBUSY  The implementation has detected an attempt to initialize or destroy a spin lock while it is in use
              (for example, while being used in a pthread_spin_lock() call) by another thread.

       EINVAL The value specified by lock is invalid.

       The pthread_spin_init() function shall fail if:

       EAGAIN The system lacks the necessary resources to initialize another spin lock.

       ENOMEM Insufficient memory exists to initialize the lock.

       These functions shall not return an error code of [EINTR].

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       The  pthread_spin_destroy()  and pthread_spin_init() functions are part of the Spin Locks option and need
       not be provided on all implementations.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       pthread_spin_lock() , pthread_spin_unlock()  ,  the  Base  Definitions  volume  of  IEEE Std 1003.1-2001,
       <pthread.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard  for  Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc and The Open Group. In the event of any discrepancy between this version and the  original  IEEE  and
       The  Open  Group  Standard,  the  original  IEEE and The Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group                                   2003                               PTHREAD_SPIN_DESTROY(P)