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 refer-
enced 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 imple-
mentation 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_bar-
rier_wait() call). The results are undefined if a barrier is used with-
out first being initialized. The results are undefined if pthread_bar-
rier_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 syn-
chronization. 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; other-
wise, 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 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 implementa-
tions.
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 .
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