timer.tcl

可以在ns-2中进行仿真的SPIN路由协议的源码

#
# A simple NewTimer class.  You can derive a subclass of NewTimer
# 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 NewTimer

# sched is the same as resched; the previous setting is cancelled
# and another event is scheduled. No state is kept for the NewTimers.
# This is different than the C++ NewTimer API in NewTimer-handler.cc,h; where a 
# sched aborts if the NewTimer is already set. C++ NewTimers maintain state 
# (e.g. IDLE, PENDING..etc) that is checked before the NewTimer is scheduled.
NewTimer instproc sched delay {
    global ns_
    $self instvar id_
    $self cancel
    set now [$ns_ now]
    set id_ [$ns_ at [expr $now + $delay] "$self timeout"]
}

NewTimer instproc destroy {} {
	$self cancel
}

NewTimer 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++ NewTimers.
NewTimer instproc resched delay {
	$self sched $delay 
}

# the subclass must provide the timeout function
NewTimer instproc expire {} {
	$self timeout
}