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.TH PTHREAD_BARRIER_DESTROY 3C "Jan 30, 2004"
.SH NAME
pthread_barrier_destroy, pthread_barrier_init \- destroy and initialize a
barrier object
.SH SYNOPSIS
.LP
.nf
cc \fB-mt\fR [ \fIflag\fR... ] \fIfile\fR... [ \fIlibrary\fR... ]
#include <pthread.h>

\fBint\fR \fBpthread_barrier_destroy\fR(\fBpthread_barrier_t *\fR\fIbarrier\fR);
.fi

.LP
.nf
\fBint\fR \fBpthread_barrier_init\fR(\fBpthread_barrier_t *\fR\fIbarrier\fR,
     \fBconst pthread_barrierattr_t *restrict\fR \fIattr\fR, \fBunsigned\fR \fIcount\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBpthread_barrier_destroy()\fR function destroys the barrier referenced by
\fIbarrier\fR and releases 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 \fBpthread_barrier_init()\fR. An implementation can use this
function to set barrier to an invalid value. The results are undefined if
\fBpthread_barrier_destroy()\fR is called when any thread is blocked on the
barrier, or if this function is called with an uninitialized barrier.
.sp
.LP
The \fBpthread_barrier_init()\fR function allocates any resources required to
use the barrier referenced by barrier and initializes the barrier with
attributes referenced by \fIattr\fR. If attr is \fINULL\fR, the default barrier
attributes are used; the effect is the same as passing the address of a default
barrier attributes object. The results are undefined if
\fBpthread_barrier_init()\fR is called when any thread is blocked on the
barrier (that is, has not returned from the \fBpthread_barrier_wait\fR(3C)
call). The results are undefined if a barrier is used without first being
initialized. The results are undefined if \fBpthread_barrier_init()\fR is
called specifying an already initialized barrier.
.sp
.LP
The \fIcount\fR argument specifies the number of threads that must call
\fBpthread_barrier_wait()\fR before any of them successfully return from the
call. The value specified by \fIcount\fR must be greater than 0.
.sp
.LP
If the \fBpthread_barrier_init()\fR function fails, the barrier is not
initialized and the contents of \fIbarrier\fR are undefined.
.sp
.LP
Only the object referenced by barrier can be used for performing
synchronization. The result of referring to copies of that object in calls to
\fBpthread_barrier_destroy()\fR or \fBpthread_barrier_wait()\fR is undefined.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, these functions returns 0. Otherwise, an error
number is returned to indicate the error.
.SH ERRORS
.sp
.LP
The \fBpthread_barrier_init()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEAGAIN\fR\fR
.ad
.RS 10n
The system lacks the necessary resources to initialize another barrier.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fIcount\fR is equal to 0.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 10n
Insufficient memory exists to initialize the barrier.
.RE

.sp
.LP
The \fBpthread_barrier_init()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBEBUSY\fR\fR
.ad
.RS 10n
The implementation has detected an attempt to destroy a barrier while it is in
use (for example, while being used in a \fBpthread_barrier_wait()\fR call) by
another thread.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fIattr\fR is invalid.
.RE

.sp
.LP
The \fBpthread_barrier_destroy()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBEBUSY\fR\fR
.ad
.RS 10n
The implementation has detected an attempt to destroy a barrier while it is in
use (for example, while being used in a \fBpthread_barrier_wait()\fR call) by
another thread.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fIbarrier\fR is invalid.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBpthread_barrier_wait\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)