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#
# A simple timer class. You can derive a subclass of Timer
# to provide a simple mechanism for scheduling events:
#
# $self sched $delay -- causes "$self timeout" to be called
# $delay seconds in the future
# $self cancel -- cancels any pending scheduled callback
#
Class Timer
# sched is the same as resched; the previous setting is cancelled
# and another event is scheduled. No state is kept for the timers.
# This is different than the C++ timer API in timer-handler.cc,h; where a
# sched aborts if the timer is already set. C++ timers maintain state
# (e.g. IDLE, PENDING..etc) that is checked before the timer is scheduled.
Timer instproc sched delay {
global ns
$self instvar id_
$self cancel
set id_ [$ns at [expr [$ns now] + $delay] "$self timeout"]
}
Timer instproc destroy {} {
$self cancel
}
Timer instproc cancel {} {
global ns
$self instvar id_
if [info exists id_] {
$ns cancel $id_
unset id_
}
}
# resched and expire are added to have a similar API to C++ timers.
Timer instproc resched delay {
$self sched $delay
}
# the subclass must provide the timeout function
Timer instproc expire {} {
$self timeout
}
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