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 .