NAME
pthread_barrier_destroy, pthread_barrier_init - destroy and initialize
a barrier object (ADVANCED REALTIME THREADS)
SYNOPSIS
#include <pthread.h>
int pthread_barrier_destroy(pthread_barrier_t *barrier);
int pthread_barrier_init(pthread_barrier_t *restrict barrier,
const pthread_barrierattr_t *restrict attr, unsigned count);
DESCRIPTION
The pthread_barrier_destroy() function shall destroy the barrier
referenced by barrier and release any resources used by the barrier.
The effect of subsequent use of the barrier is undefined until the
barrier is reinitialized by another call to pthread_barrier_init(). An
implementation may use this function to set barrier to an invalid
value. The results are undefined if pthread_barrier_destroy() is called
when any thread is blocked on the barrier, or if this function is
called with an uninitialized barrier.
The pthread_barrier_init() function shall allocate any resources
required to use the barrier referenced by barrier and shall initialize
the barrier with attributes referenced by attr. If attr is NULL, the
default barrier attributes shall be used; the effect is the same as
passing the address of a default barrier attributes object. The results
are undefined if pthread_barrier_init() is called when any thread is
blocked on the barrier (that is, has not returned from the
pthread_barrier_wait() call). The results are undefined if a barrier is
used without first being initialized. The results are undefined if
pthread_barrier_init() is called specifying an already initialized
barrier.
The count argument specifies the number of threads that must call
pthread_barrier_wait() before any of them successfully return from the
call. The value specified by count must be greater than zero.
If the pthread_barrier_init() function fails, the barrier shall not be
initialized and the contents of barrier are undefined.
Only the object referenced by barrier may be used for performing
synchronization. The result of referring to copies of that object in
calls to pthread_barrier_destroy() or pthread_barrier_wait() is
undefined.
RETURN VALUE
Upon successful completion, these functions shall return zero;
otherwise, an error number shall be returned to indicate the error.
ERRORS
The pthread_barrier_destroy() function may fail if:
EBUSY The implementation has detected an attempt to destroy a barrier
while it is in use (for example, while being used in a
pthread_barrier_wait() call) by another thread.
EINVAL The value specified by barrier is invalid.
The pthread_barrier_init() function shall fail if:
EAGAIN The system lacks the necessary resources to initialize another
barrier.
EINVAL The value specified by count is equal to zero.
ENOMEM Insufficient memory exists to initialize the barrier.
The pthread_barrier_init() function may fail if:
EBUSY The implementation has detected an attempt to reinitialize a
barrier while it is in use (for example, while being used in a
pthread_barrier_wait() call) by another thread.
EINVAL The value specified by attr is invalid.
These functions shall not return an error code of [EINTR].
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
The pthread_barrier_destroy() and pthread_barrier_init() functions are
part of the Barriers option and need not be provided on all
implementations.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
pthread_barrier_wait() , 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 .