#!/mod/bin/jimsh

proc _lock_to_port {id} {
	set len [string length $id]
	set hash $len

	for {set i 0} {$i < $len} {incr i} {
		scan [string index $id $i] "%c" asc
		set hash [expr (($hash<<5)^($hash>>27))^$asc];
	}

	return [expr (65535 - ($hash % 101))]
}

proc _lock_dummy {newsock addr port} { }

proc acquire_lock {id {timeout 0}} {
	global _locks

	set port [_lock_to_port $id]

	incr timeout [clock seconds]

	while {[catch {set socket [\
	    socket stream.server "127.0.0.1:$port"]} msg]} {
		if {[clock seconds] > $timeout} { return 0 }
		sleep 0.2
	}

	set _locks($id) $socket
	return 1
}

proc release_lock {id} {
	global _locks

	if {[catch {close $_locks($id)} msg]} {
		puts "Error releasing lock: $msg"
		return 0
	}
	unset _locks($id)
	return 1
}