gcc/lock-and-run.sh

   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.