|
111
|
1 #! /bin/sh
|
|
|
2 # Shell-based mutex using mkdir.
|
|
|
3
|
|
|
4 lockdir="$1" prog="$2"; shift 2 || exit 1
|
|
|
5
|
|
|
6 # Remember when we started trying to acquire the lock.
|
|
|
7 count=0
|
|
|
8 touch lock-stamp.$$
|
|
|
9
|
|
|
10 trap 'rm -r "$lockdir" lock-stamp.$$' 0
|
|
|
11
|
|
|
12 until mkdir "$lockdir" 2>/dev/null; do
|
|
|
13 # Say something periodically so the user knows what's up.
|
|
|
14 if [ `expr $count % 30` = 0 ]; then
|
|
|
15 # Reset if the lock has been renewed.
|
|
|
16 if [ -n "`find \"$lockdir\" -newer lock-stamp.$$`" ]; then
|
|
|
17 touch lock-stamp.$$
|
|
|
18 count=1
|
|
|
19 # Steal the lock after 5 minutes.
|
|
|
20 elif [ $count = 300 ]; then
|
|
|
21 echo removing stale $lockdir >&2
|
|
|
22 rm -r "$lockdir"
|
|
|
23 else
|
|
|
24 echo waiting to acquire $lockdir >&2
|
|
|
25 fi
|
|
|
26 fi
|
|
|
27 sleep 1
|
|
|
28 count=`expr $count + 1`
|
|
|
29 done
|
|
|
30
|
|
|
31 echo $prog "$@"
|
|
|
32 $prog "$@"
|
|
|
33
|
|
|
34 # The trap runs on exit.
|
