115 lines
3.3 KiB
Groff
115 lines
3.3 KiB
Groff
.\" Copyright (c) 2016 The FreeBSD Foundation, Inc.
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.\"
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.\" This documentation was written by
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.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship
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.\" from the FreeBSD Foundation.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd May 5, 2020
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.Dt THR_WAKE 2
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.Os
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.Sh NAME
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.Nm thr_wake
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.Nd wake up the suspended thread
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/thr.h
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.Ft int
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.Fn thr_wake "long id"
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.Sh DESCRIPTION
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.Bf -symbolic
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This function is intended for implementing threading.
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Normal applications should use
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.Xr pthread_cond_timedwait 3
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together with
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.Xr pthread_cond_broadcast 3
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for typical safe suspension with cooperation of the thread
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being suspended, or
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.Xr pthread_suspend_np 3
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and
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.Xr pthread_resume_np 3
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in some specific situations, instead.
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.Ef
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.Pp
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Passing the thread identifier of the calling thread
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.Po
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see
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.Xr thr_self 2
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.Pc
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to
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.Fn thr_wake
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sets a thread's flag to cause the next signal-interruptible sleep
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of that thread in the kernel to fail immediately with the
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.Er EINTR
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error.
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The flag is cleared by an interruptible sleep attempt or by a call to
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.Xr thr_suspend 2 .
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This is used by the system threading library to implement cancellation.
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.Pp
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If
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.Fa id
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is not equal to the current thread identifier, the specified thread is
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woken up if suspended by the
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.Xr thr_suspend 2
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system call.
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If the thread is not suspended at the time of the
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.Nm
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call, the wake is remembered and the next attempt of the thread to
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suspend itself with the
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.Xr thr_suspend 2
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results in immediate return with success.
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Only one wake is remembered.
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.Sh RETURN VALUES
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.Rv -std thr_wake
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.Sh ERRORS
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The
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.Fn thr_wake
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operation returns these errors:
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.Bl -tag -width Er
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.It Bq Er ESRCH
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The specified thread was not found or does not belong to the process
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of the calling thread.
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.El
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.Sh SEE ALSO
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.Xr ps 1 ,
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.Xr thr_self 2 ,
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.Xr thr_suspend 2 ,
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.Xr pthread_cancel 3 ,
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.Xr pthread_resume_np 3 ,
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.Xr pthread_suspend_np 3
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.Sh STANDARDS
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The
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.Fn thr_suspend
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system call is non-standard and is used by
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.Lb libthr
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to implement
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.St -p1003.1-2001
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.Xr pthread 3
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functionality.
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.Sh HISTORY
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The
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.Fn thr_suspend
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system call first appeared in
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.Fx 5.2 .
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