137 lines
5.3 KiB
Groff
137 lines
5.3 KiB
Groff
.\" $NetBSD: rt_timer.9,v 1.4 1999/03/16 00:40:47 garbled Exp $
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.\"
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.\" Copyright (c) 1998 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Kevin M. Lahey of the Numerical Aerospace Simulation Facility,
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.\" NASA Ames Research Center.
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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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgment:
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.\" This product includes software developed by the NetBSD
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.\" Foundation, Inc. and its contributors.
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.\" 4. Neither the name of The NetBSD Foundation nor the names of its
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.\" contributors may be used to endorse or promote products derived
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.\" from this software without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd April 23, 1998
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.Dt RT_TIMER 9
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.Os
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.Sh NAME
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.Nm rt_timer ,
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.Nm rt_timer_add ,
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.Nm rt_timer_queue_create ,
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.Nm rt_timer_queue_change ,
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.Nm rt_timer_queue_destroy ,
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.Nm rt_timer_remove_all
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.Nd route callout functions
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.Sh SYNOPSIS
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.Fd #include <net/route.h>
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.Ft "struct rttimer_queue *"
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.Fn rt_timer_queue_create "time_t timeout"
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.Ft void
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.Fn rt_timer_queue_change "struct rttimer_queue *q" "time_t timeout"
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.Ft void
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.Fn rt_timer_queue_destroy "struct rttimer_queue *q" "int destroy"
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.Ft int
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.Fn rt_timer_add "struct rtentry *rt" \
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"void(*f)(struct rtentry *, struct rttimer *)" "struct rttimer_queue *q"
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.Ft void
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.Fn rt_timer_remove_all "struct rtentry *rt"
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.Sh DESCRIPTION
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The
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.Nm
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functions provide a generic route callout functionality.
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They allow a function to be called for a route at any time.
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This was originally intended to be used to remove routes added
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by path MTU discovery code.
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.Pp
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For maximum efficiency, a separate queue should be defined for each
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timeout period. For example, one queue should be created for the
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10 minute path MTU discovery timeouts, another for 20 minute ARP
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timeouts after 20 minutes, and so on. This permits extremely fast
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queue manipulations so that the timeout functions remain scalable,
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even in the face of thousands of route manipulations per minute.
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.Pp
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It is possible to create only a single timeout queue for all possible
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timeout values, but doing so is not scalable as queue manipulations
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become quite expensive if the timeout deltas are not roughly constant.
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.Pp
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The
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.Nm
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interface provides the following functions:
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.Bl -tag -width compact
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.It Fn rt_timer_queue_create "time_t timeout"
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This function creates a new timer queue with the specified timeout period
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.Fa timeout ,
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expressed in seconds.
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.It Fn rt_timer_queue_change "rttimer_queue *q" "time_t timeout"
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This function modifies the timeout period for a timer queue.
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Any value, including 0, is valid. The next time the timer queue's
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timeout expires (based on the previous timeout value), all entries
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which are valid to execute based on the new timeout will be executed,
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and the new timeout period scheduled.
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.It Fn rt_timer_queue_destroy "rttimer_queue *q" "int destroy"
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This function destroys a timeout queue. All entries are removed,
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and if the
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.Fa destroy
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argument is non-zero, the timeout action is performed for each entry.
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.It Fn rt_timer_add "struct rtentry *rt" \
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"void(*f)(struct rtentry *, struct rttimer *)" "struct rttimer_queue *q"
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This function adds an entry to a timeout queue.
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The function
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.Fa f
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will be called after the timeout period for queue
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.Fa q
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has elapsed.
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If
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.Fa f
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is NULL
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the route will be deleted when the timeout expires.
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.It Fn rt_timer_remove_all "struct rtentry *rt"
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This function removes all references to the given route from the
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.Nm
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subsystem. This is used when a route is deleted to ensure that no
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dangling references remain.
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.El
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.Sh SEE ALSO
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.Xr arp 9 ,
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.Xr netstat 1
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.Sh AUTHORS
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This interface is roughly based on (but, alas, not compatable with) one
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designed by David Borman of BSDI. This implementation is by Kevin Lahey
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of the Numerical Aerospace Simulation Facility, NASA Ames Research Center.
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.Sh CODE REFERENCES
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The
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.Nm
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interface is implemented in
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.Pa sys/net/route.h
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and
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.Pa sys/net/route.c.
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.Sh HISTORY
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The
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.Nm
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interface appeared in
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.Nx 1.4 .
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