#!/bin/bash
#
# vcached: VServer cache daemon
#
# Description: A daemon that periodically preallocates vservers and stores
# them in a cache.  Preallocated vservers from the cache may be then used to 
# instantiate real vservers. Requires that /var/run/vcached.pid does not
# exist on startup. Should start/stop/restart from /etc/init.d. Can also be
# run periodically with -s from /etc/cron.d.
#
# Based on work by:
# 
# Brent Chun - bnc@intel-research.net
# Tristan Koo - tristan.koo@intel-research.net
# William Wung - wungism@uclink.berkeley.edu
#
# Mark Huang <mlhuang@cs.princeton.edu>
# Copyright (c) 2004  The Trustees of Princeton University (Trustees).
#
# $Id: vcached,v 1.7 2004/11/17 20:34:25 mef Exp $
#

# get configuration
. /etc/vcached.conf

# parse options
while getopts 'fdsl:' OPT ; do
    case "$OPT" in
        f) foreground=1 ;;
        d) debug=1 ;;
	s) single=1 ;;
	l) exec 1>>$OPTARG ; exec 2>>$OPTARG ;;
    esac
done

# check if we are already running
if [ -f $pidfile ] ; then
    echo "vcached(`cat $pidfile`) already running"
    exit 1
fi

# daemonize
if [ $foreground -eq 0 ] ; then
    nohup setsid nice -n $nice -- $0 $* -f -l $logfile >/dev/null 2>&1 </dev/null &
    exit 0
fi

# record PID
trap "rm -f $pidfile ; exit 255" EXIT
trap "exec 1>>$logfile ; exec 2>>$logfile" HUP
echo $$ > $pidfile

: ${UTIL_VSERVER_VARS:=$(dirname $0)/util-vserver-vars}
test -e "$UTIL_VSERVER_VARS" || {
    echo "Can not find util-vserver installation; aborting..."
    exit 1
}
. "$UTIL_VSERVER_VARS"

# take out the trash
chattr -R -i "$VROOTDIR/.vtmp"
rm -rf "$VROOTDIR/.vtmp"

mkdir -p "$VROOTDIR/.vcache"
mkdir -p "$VROOTDIR/.vtmp"

# loop forever
while : ; do
    [ $debug -ne 0 ] && echo "$(date) Checking the cache"
    for i in $(seq 0 $(($slots - 1))) ; do
	if [ ! -d "$VROOTDIR/.vcache/v$i" ] ; then
	    echo "$(date) Caching v$i"
	    # build image in .vtmp
	    TMP=$(mktemp -d "$VROOTDIR/.vtmp/v$i.XXXXXX")
	    "$PKGLIBDIR/vbuild" "$VROOTDIR/vserver-reference" "$TMP"
	    RETVAL=$?
	    # move it to .vcache when complete
	    if [ $RETVAL -eq 0 ] ; then
    	         # sanity check
		vnewsize=$(du -s "$TMP" | awk "{ print \$1 }")
		vrefsize=$(du -s "$VROOTDIR/vserver-reference" | awk "{ print \$1 }")
		if [ $vnewsize -lt $vrefsize ] ; then
		    echo "WARNING: Unexpected for 'du -s $VROOTDIR/$NAME'=$vnewsize to be less than 'du -s $VROOTDIR/vserver-reference'=$vrefsize"
		fi

		mv "$TMP" "$VROOTDIR/.vcache/v$i"
		echo "$(date) v$i ready"
	    else
		echo "$(date) Error $RETVAL building v$i"
		chattr -R -i "$TMP"
		rm -rf "$TMP"
	    fi
	fi
    done
    # just run once
    if [ $single -ne 0 ] ; then
	break
    fi
    [ $debug -ne 0 ] && echo "$(date) Sleeping for $period seconds"
    sleep $period
done