#!/bin/sh

PS=/bin/ps
SLEEP=/bin/sleep
KILL=/bin/kill
LOGGER=/usr/bin/logger
TAG=rss-watchdog

usage()
{
	echo "$0 -p <pid> -k <kilobytes> [-w <secs>] [-s <signalname>]"
	echo " Defaults: -w 5 -s SIGTERM"
	exit 0
}

secs=5
signame=SIGTERM
while getopts p:k:w:s:? o; do
	case $o in
	p) pid=$OPTARG;;
	k) kb=$OPTARG;;
	w) secs=$OPTARG;;
	s) signame=$OPTARG;;
	?) usage;;
	esac
done
if [ -z "$pid" -o -z "$kb" ]; then
	usage
fi

$LOGGER -t $TAG "Starting (pid=$pid rss=$kb wait=$secs sig=$signame)"
while true; do

	rss=$($PS -p $pid -o rss=)
	if [ -z "$rss" ]; then
		$LOGGER -t $TAG "Exiting (pid=%pid vanished)"
		break
	fi
	if [ $rss -gt $kb ]; then
		$LOGGER -t $TAG "Killing (pid=$pid rss=$rss>$kb sig=$signame)"
		$KILL -s $signame $pid
	fi

	$SLEEP $secs
done