mirror of https://github.com/mkerrisk/man-pages
182 lines
4.4 KiB
Groff
182 lines
4.4 KiB
Groff
.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
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.\" <mtk.manpages@gmail.com>
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.TH PTHREAD_TRYJOIN_NP 3 2021-08-27 "Linux" "Linux Programmer's Manual"
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.SH NAME
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pthread_tryjoin_np, pthread_timedjoin_np \- try to join with a
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terminated thread
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.SH SYNOPSIS
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.nf
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.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
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.B #include <pthread.h>
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.PP
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.BI "int pthread_tryjoin_np(pthread_t " thread ", void **" retval );
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.BI "int pthread_timedjoin_np(pthread_t " thread ", void **" retval ,
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.BI " const struct timespec *" abstime );
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.fi
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.PP
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Compile and link with \fI\-pthread\fP.
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.SH DESCRIPTION
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These functions operate in the same way as
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.BR pthread_join (3),
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except for the differences described on this page.
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.PP
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The
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.BR pthread_tryjoin_np ()
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function performs a nonblocking join with the thread
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.IR thread ,
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returning the exit status of the thread in
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.IR *retval .
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If
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.I thread
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has not yet terminated, then instead of blocking, as is done by
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.BR pthread_join (3),
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the call returns an error.
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.PP
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The
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.BR pthread_timedjoin_np ()
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function performs a join-with-timeout.
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If
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.I thread
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has not yet terminated,
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then the call blocks until a maximum time, specified in
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.IR abstime ,
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measured against the
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.BR CLOCK_REALTIME
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clock.
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If the timeout expires before
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.I thread
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terminates,
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the call returns an error.
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The
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.I abstime
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argument is a structure of the following form,
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specifying an absolute time measured since the Epoch (see
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.BR time (2)):
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.PP
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.in +4n
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.EX
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struct timespec {
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time_t tv_sec; /* seconds */
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long tv_nsec; /* nanoseconds */
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};
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.EE
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.in
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.SH RETURN VALUE
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On success,
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these functions return 0;
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on error, they return an error number.
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.SH ERRORS
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These functions can fail with the same errors as
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.BR pthread_join (3).
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.BR pthread_tryjoin_np ()
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can in addition fail with the following error:
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.TP
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.B EBUSY
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.I thread
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had not yet terminated at the time of the call.
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.PP
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.BR pthread_timedjoin_np ()
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can in addition fail with the following errors:
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.TP
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.BR EINVAL
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.I abstime
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value is invalid
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.RI ( tv_sec
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is less than 0 or
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.IR tv_nsec
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is greater than 1e9).
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.TP
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.BR ETIMEDOUT
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The call timed out before
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.I thread
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terminated.
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.PP
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.BR pthread_timedjoin_np ()
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never returns the error
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.BR EINTR .
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.SH VERSIONS
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These functions first appeared in glibc in version 2.3.3.
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.ad l
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.nh
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.TS
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allbox;
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lbx lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR pthread_tryjoin_np (),
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.BR pthread_timedjoin_np ()
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T} Thread safety MT-Safe
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.TE
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.hy
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.ad
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.sp 1
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.SH CONFORMING TO
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These functions are nonstandard GNU extensions;
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hence the suffix "_np" (nonportable) in the names.
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.SH BUGS
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The
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.BR pthread_timedjoin_np ()
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function measures time by internally calculating a relative sleep interval
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that is then measured against the
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.BR CLOCK_MONOTONIC
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clock instead of the
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.BR CLOCK_REALTIME
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clock.
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Consequently, the timeout is unaffected by discontinuous changes to the
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.BR CLOCK_REALTIME
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clock.
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.SH EXAMPLES
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The following code waits to join for up to 5 seconds:
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.PP
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.in +4n
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.EX
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struct timespec ts;
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int s;
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\&...
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if (clock_gettime(CLOCK_REALTIME, &ts) == \-1) {
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/* Handle error */
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}
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ts.tv_sec += 5;
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s = pthread_timedjoin_np(thread, NULL, &ts);
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if (s != 0) {
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/* Handle error */
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}
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.EE
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.in
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.SH SEE ALSO
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.BR clock_gettime (2),
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.BR pthread_exit (3),
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.BR pthread_join (3),
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.BR pthreads (7)
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