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NetBSD 6.1.5 - man page for rt_timer_queue_change (netbsd section 9)

RT_TIMER(9)			  BSD Kernel Developer's Manual 		      RT_TIMER(9)

     rt_timer, rt_timer_add, rt_timer_queue_create, rt_timer_queue_change,
     rt_timer_queue_destroy, rt_timer_remove_all -- route callout functions

     #include <net/route.h>

     struct rttimer_queue *
     rt_timer_queue_create(time_t timeout);

     rt_timer_queue_change(struct rttimer_queue *q, time_t timeout);

     rt_timer_queue_destroy(struct rttimer_queue *q, int destroy);

     rt_timer_add(struct rtentry *rt, void(*f)(struct rtentry *, struct rttimer *),
	 struct rttimer_queue *q);

     rt_timer_remove_all(struct rtentry *rt);

     The rt_timer functions provide a generic route callout functionality.  They allow a function
     to be called for a route at any time.  This was originally intended to be used to remove
     routes added by path MTU discovery code.

     For maximum efficiency, a separate queue should be defined for each timeout period.  For
     example, one queue should be created for the 10 minute path MTU discovery timeouts, another
     for 20 minute ARP timeouts after 20 minutes, and so on.  This permits extremely fast queue
     manipulations so that the timeout functions remain scalable, even in the face of thousands
     of route manipulations per minute.

     It is possible to create only a single timeout queue for all possible timeout values, but
     doing so is not scalable as queue manipulations become quite expensive if the timeout deltas
     are not roughly constant.

     The rt_timer interface provides the following functions:

     rt_timer_queue_create(time_t timeout)
	      This function creates a new timer queue with the specified timeout period timeout,
	      expressed in seconds.

     rt_timer_queue_change(rttimer_queue *q, time_t timeout)
	      This function modifies the timeout period for a timer queue.  Any value, including
	      0, is valid.  The next time the timer queue's timeout expires (based on the previ-
	      ous timeout value), all entries which are valid to execute based on the new timeout
	      will be executed, and the new timeout period scheduled.

     rt_timer_queue_destroy(rttimer_queue *q, int destroy)
	      This function destroys a timeout queue.  All entries are removed, and if the
	      destroy argument is non-zero, the timeout action is performed for each entry.

     rt_timer_add(struct rtentry *rt, void(*f)(struct rtentry *, struct rttimer *), struct
	      rttimer_queue *q)
	      This function adds an entry to a timeout queue.  The function f will be called
	      after the timeout period for queue q has elapsed.  If f is NULL the route will be
	      deleted when the timeout expires.

     rt_timer_remove_all(struct rtentry *rt)
	      This function removes all references to the given route from the rt_timer subsys-
	      tem.  This is used when a route is deleted to ensure that no dangling references

     netstat(1), arp(9)

     The rt_timer interface appeared in NetBSD 1.4.

     This interface is roughly based on (but, alas, not compatible with) one designed by David
     Borman of BSDI.  This implementation is by Kevin Lahey of the Numerical Aerospace Simulation
     Facility, NASA Ames Research Center.

     The rt_timer interface is implemented in sys/net/route.h and sys/net/route.c.

BSD					  April 23, 1998				      BSD

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