PTHREAD_SPIN_DESTROY(P)

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 .