90 lines
2.7 KiB
Groff
90 lines
2.7 KiB
Groff
.\"
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.\" Copyright (c) 1996 Joerg Wunsch
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.\"
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.\" All rights reserved.
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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 DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $Id: timeout.9,v 1.3 1997/02/22 13:26:29 peter Exp $
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.\" "
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.Dd April 13, 1996
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.Os
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.Dt TIMEOUT 9
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.Sh NAME
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.Nm timeout ,
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.Nm untimeout
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.Nd schedule timer events
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.Sh SYNOPSIS
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.Fd #include <sys/param.h>
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.Fd #include <sys/systm.h>
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.Ft typedef void timeout_t \*(lpvoid *\*(rp;
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.Ft void
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.Fn timeout "timeout_t *func" "void *arg" "int ticks"
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.Ft void
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.Fn untimeout "timeout_t *func" "void *arg"
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.Sh DESCRIPTION
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The
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.Nm timeout
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facility allows the execution of a function after a specified amount
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of time. The function
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.Ar func
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is being called with the opaque argument
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.Ar arg
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after
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.Ar ticks
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timer ticks have been elapsed. It's often convenient to use the
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external variable
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.Dv hz
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to compute the amount of
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.Ar ticks
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to wait.
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.Pp
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If the timeout event should be removed before the timer expires,
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.Nm untimeout
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must be called with the exact
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.Ar func
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and
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.Ar arg
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arguments as the corresponding call to
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.Fn timeout .
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.Pp
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Unlike the functions of
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.Xr sleep 9 ,
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.Fn timeout
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and
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.Fn untimeout
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can be called from within an interrupt context.
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.Sh SEE ALSO
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.Xr sleep 9
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.Sh HISTORY
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The
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.Nm timeout
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facility is very old.
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.Sh BUGS
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Since the timer queue is sorted and uses time differences rather than
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absolute times, inserting and removing timer events can be costly if
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it is done too frequently.
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.Sh AUTHORS
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This man page has been written by
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.ie t J\(:org Wunsch.
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.el Joerg Wunsch.
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