mirror of https://github.com/mkerrisk/man-pages
105 lines
3.8 KiB
Plaintext
105 lines
3.8 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "PTHREAD_BARRIER_WAIT" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" pthread_barrier_wait
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.SH NAME
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pthread_barrier_wait \- synchronize at a barrier (\fBADVANCED REALTIME
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THREADS\fP)
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.SH SYNOPSIS
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.LP
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\fB#include <pthread.h>
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.br
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.sp
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int pthread_barrier_wait(pthread_barrier_t *\fP\fIbarrier\fP\fB);
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\fP
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\fB
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.br
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\fP
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.SH DESCRIPTION
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.LP
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The \fIpthread_barrier_wait\fP() function shall synchronize participating
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threads at the barrier referenced by \fIbarrier\fP.
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The calling thread shall block until the required number of threads
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have called \fIpthread_barrier_wait\fP() specifying the
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barrier.
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.LP
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When the required number of threads have called \fIpthread_barrier_wait\fP()
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specifying the barrier, the constant
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PTHREAD_BARRIER_SERIAL_THREAD shall be returned to one unspecified
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thread and zero shall be returned to each of the remaining
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threads. At this point, the barrier shall be reset to the state it
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had as a result of the most recent \fIpthread_barrier_init\fP() function
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that referenced it.
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.LP
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The constant PTHREAD_BARRIER_SERIAL_THREAD is defined in \fI<pthread.h>\fP
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and
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its value shall be distinct from any other value returned by \fIpthread_barrier_wait\fP().
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.LP
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The results are undefined if this function is called with an uninitialized
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barrier.
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.LP
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If a signal is delivered to a thread blocked on a barrier, upon return
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from the signal handler the thread shall resume waiting
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at the barrier if the barrier wait has not completed (that is, if
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the required number of threads have not arrived at the barrier
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during the execution of the signal handler); otherwise, the thread
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shall continue as normal from the completed barrier wait. Until
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the thread in the signal handler returns from it, it is unspecified
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whether other threads may proceed past the barrier once they
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have all reached it.
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.LP
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A thread that has blocked on a barrier shall not prevent any unblocked
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thread that is eligible to use the same processing
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resources from eventually making forward progress in its execution.
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Eligibility for processing resources shall be determined by the
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scheduling policy.
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.SH RETURN VALUE
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.LP
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Upon successful completion, the \fIpthread_barrier_wait\fP() function
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shall return PTHREAD_BARRIER_SERIAL_THREAD for a single
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(arbitrary) thread synchronized at the barrier and zero for each of
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the other threads. Otherwise, an error number shall be returned
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to indicate the error.
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.SH ERRORS
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.LP
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The \fIpthread_barrier_wait\fP() function may fail if:
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.TP 7
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.B EINVAL
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The value specified by \fIbarrier\fP does not refer to an initialized
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barrier object.
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.sp
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.LP
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This function shall not return an error code of [EINTR].
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.LP
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\fIThe following sections are informative.\fP
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.SH EXAMPLES
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.LP
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None.
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.SH APPLICATION USAGE
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.LP
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Applications using this function may be subject to priority inversion,
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as discussed in the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, Section 3.285, Priority Inversion.
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.LP
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The \fIpthread_barrier_wait\fP() function is part of the Barriers
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option and need not be provided on all implementations.
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.SH RATIONALE
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.LP
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None.
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.SH FUTURE DIRECTIONS
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.LP
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None.
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.SH SEE ALSO
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.LP
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\fIpthread_barrier_destroy\fP() , the Base Definitions volume of
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IEEE\ Std\ 1003.1-2001, \fI<pthread.h>\fP
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.SH COPYRIGHT
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Portions of this text are reprinted and reproduced in electronic form
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from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
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-- Portable Operating System Interface (POSIX), The Open Group Base
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Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
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Electrical and Electronics Engineers, Inc and The Open Group. In the
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event of any discrepancy between this version and the original IEEE and
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The Open Group Standard, the original IEEE and The Open Group Standard
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is the referee document. The original Standard can be obtained online at
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http://www.opengroup.org/unix/online.html .
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