mguardian

一个内存数据库的源代码这是服务器端还有客户端

#!/bin/bash
# The contents of this file are subject to the MonetDB Public License
# Version 1.1 (the "License"); you may not use this file except in
# compliance with the License. You may obtain a copy of the License at
# http://monetdb.cwi.nl/Legal/MonetDBLicense-1.1.html
#
# Software distributed under the License is distributed on an "AS IS"
# basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
# License for the specific language governing rights and limitations
# under the License.
#
# The Original Code is the MonetDB Database System.
#
# The Initial Developer of the Original Code is CWI.
# Portions created by CWI are Copyright (C) 1997-2007 CWI.
# All Rights Reserved.

# The mguardian looks after the healthyness of invidual servers
# A mguardian process is run for each mserver unless you specify
# otherwise.
# The mguardian control information is kept in .mguardian and
# consists of the <delay,pid> pair

function usage()
{
	echo "Usage: mguardian [options] [mserver(s)]"
	echo "    --start        Start looking after mserver(s)[default]"
	echo "    --stop         Stop looking after mserver(s) "
	echo "    --delay        Set check delay to N seconds [300]"
	echo "    --status       Status of all servers"
	echo "    --log          Display the server log"
	echo "    --help         This list of options"
}

function get() {
	needle=$1
	shift
	while [ $# -gt 0 ];
	do
		arg=${1#${needle}=}
		[[ ${#arg} -lt ${#1} ]] && echo $arg
		shift
	done
}

tmp="$(get "--dbfarm" $*)"
if [ ! -z "$tmp" ]
then
	DBFARM="$tmp"
	DBLOGS=$DBFARM/../dblogs
	echo "mguardian working on " $DBFARM
else
	DBFARM=$MONETDB5_PREFIX/var/MonetDB5/dbfarm
	DBLOGS=$MONETDB5_PREFIX/var/MonetDB5/dblogs
fi
DELAY=300
ACTION=start

trap '' 2 3

case "$1" in
 "--start" )
	ACTION=start
	shift
	;;
 "--stop" )
	ACTION=stop
	shift
	;;
 "--delay="* )
	delay="${1#--delay=}"
	if [ "$delay" != "" ];
	then 
		DELAY=$delay
	fi
	ACTION=delay
	shift
	;;
 "--help" | * )
	usage 
	exit 0
	;;
esac

cd $DBFARM
if [ ! -z "$*" ]
then
	DBLIST="$*"
else
	DBLIST="`ls`"
fi

tmp="$(get "--dbname" $*)"
if [ ! -z "$tmp" ]
then
	DBLIST="$tmp"
fi

function getPID ()
{
	active=""
	if [ -f $1/.gdk_lock ]
	then
		pid=`sed -e "s/.*PID=//" -e "s/ .*//" -e 2q $1/.gdk_lock`
		if [ "$pid" != "" ]
		then
			active=`ps --no-heading --format pid -p $pid`
		fi
	fi
	echo $active
}

# before we restart we have to test for a bad system environment,
# such as a full disk
restartcount=0
maxtrials=8
mailtrigger=1
restartwindow=60
started=`date +%s`

function restart_server()
{
	# FIXME: add support for $DBLOGS someday; it can also grow beyond
	#        disk capacities...
	full=`df $DBFARM/$1 |sed -e 1d -e "s/%.*//" -e "s/.* //"` 

	if [[ "$restartcount" > $maxtrials  ]]
	then
		return
	fi
	if [ "$full" -gt 90 ]
	then
		echo "Running out of disk space"
		echo `date +"%F %T"` "WARNING disk use $full%" >>monetdb.log
		if [[ "$restartcount" > $mailtrigger  ]]
		then
mail -s "Notification: mserver5 encounters disk limits" $USER <<!EOF
The mguardian process $$ running on node `uname -n` has detected
that you are running low on disk space.
The endangered database is located in '$DBFARM/$1'.
`df -h $DBFARM/$1 $DBLOGS/$1 | tail -n +2 | sort | uniq`
The space taken by the database:
`du -shc $DBFARM/$1 $DBLOGS/$1`
Please take precautions against loosing your data.
!EOF
		fi
	fi

	now=`date +%s`
	now=`expr $now - $started `
	if [[ "$now" < "$restartwindow" ]]
	then
		if [[ "$restartcount" > $mailtrigger ]]
		then
			if [[ "$restartcount" == $maxtrials ]]
			then
			mail -s "Notification: mserver5 stopped" $USER <<!EOF
The mguardian process $$ running on node `uname -n` has attempted
to restart the server against database '$1' $maxtrials times.
The server remains down until you have checked the situation.
!EOF
			fi
			now=`date`
			mail -s "Notification: mserver5 restarted" $USER <<!EOF
The mguardian process $$ running on node `uname -n` has restarted
database '$1' because it appeared not to be running any more.
Please inspect the monetdb log for further details.

The mguardian process is removed when the server is properly
terminated with e.g. 'monetdb --stop --dbname=$1'.
Alternatively, you can safely kill process $$, but then the
server is left unattended.
!EOF
			# todo: add some information on the how manieth message this
			# is, and implement a gag, in order to stop sending mail
			# (the *2 each time is not enough, imho, it should stop
			# trying and send a message that the database is down and
			# stays down)
			mailtrigger=`expr $mailtrigger + $mailtrigger`
		fi
		restartcount=`expr $restartcount + 1 `
	fi
	if [ -f $1/.mserver5.args ]
	then
		started=`date +%s`
		if [ -f $1/.mserver5.dbinit ]
        then
            STARTUP=$DBFARM/$1/.mserver5.dbinit
        fi
		if [ -f $1/.mserver5.args ]
		then
			ARGS=`cat $1/.mserver5.args`
		fi
        CONFIG="--config=$DBFARM/$1/.monetdb.conf"
		(cd $1; mserver5 --set daemon=yes --dbname=$1 $CONFIG $ARGS $STARTUP)&
		echo `date +"%F %T"` " RESTART $1 $args" >>monetdb.log
	fi
}

function getDelay()
{
 	delay=`grep delay $1/.monetdb.conf| sed -e "s/\t.*//" -e "s/delay=//"`
	if [ "$delay" = "" ]
	then
		delay=11
	fi
	echo $delay
}
#for each mserver5 a separate mguardian process is started
#it runs in the background until the mguardian control file disappears
function check_mserver()
{
	delay=`getDelay $1`
	mypid=$!
	echo "$delay" >$1/.mguardian.delay
	echo "$!" >$1/.mguardian.pid
	echo `date +"%F %T"` " GUARD $1 " >>monetdb.log

	while [ -f $1/.mguardian.pid ]
	do
		active=`getPID $1`
		if  [ "$active" = "" ]
		then
			restart_server $1
		fi
		# we should pick a cheaper way to detect changes to the delay
		delay=`getDelay $1`
		sleep $delay &
		sid="$!"
		echo "$sid" >$1/.mguardian.sleep
		trap "kill $sid" 1
		wait
		trap 1
	done
	echo `date +"%F %T"` " LEAVE $1 " >>monetdb.log
	exit
}

#ignore a server also involves killing any running mguardian
# for it. 
function stop_guardian()
{
	pid=`getPID $1`
	if [ -f $DBFARM/$1/.mguardian.pid ]
	then
		pid=`cat $DBFARM/$1/.mguardian.pid`
		echo -n "stop mguardian for " $DBFARM/$1 "..."
		kill -TERM $pid
		echo "ok"
		echo `date +"%F %T"` " LEAVE $1 " >>monetdb.log
		rm $1/.mguardian.pid
	fi
}


#echo "mguardian dblist $DBLIST"
case $ACTION in
	"start" )
		for i in $DBLIST
		do
			( check_mserver  $i )  &
		done
		;;
	"stop" )
		for i in $DBLIST
		do
			if [ -d $i ]
			then
				stop_guardian $i
			fi
		done
		;;
	"delay" )
		for i in $DBLIST
		do
			if [ -d $i ]
			then
				if [ -f $i/.mguardian.sleep ]
				then
					#wakeup the mguardian process
					pid=`cat $i/.mguardian.sleep`
					kill -HUP $pid
				fi
				echo "$DELAY" >$i/.mguardian.delay
			fi
		done
		;;
esac