lib/interlock

   1 #! /bin/sh
   2
   3 # interlock - wrap program invocation in lock to allow
   4 #             parallel builds to work.
   5 # Written by Tom Tromey <tromey@cygnus.com>, Aug 10 1996
   6 #
   7 # This program is free software; you can redistribute it and/or modify
   8 # it under the terms of the GNU General Public License as published by
   9 # the Free Software Foundation; either version 2, or (at your option)
  10 # any later version.
  11 #
  12 # This program is distributed in the hope that it will be useful,
  13 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 # GNU General Public License for more details.
  16 #
  17 # You should have received a copy of the GNU General Public License
  18 # along with this program; if not, write to the Free Software
  19 # Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  20
  21 # Usage:
  22 #   interlock lock-dir-name program args-to-program...
  23
  24 dirname="$1"
  25 program="$2"
  26
  27 shift
  28 shift
  29
  30 while (mkdir $dirname > /dev/null 2>&1 && exit 1 || exit 0); do
  31    # Wait a bit.
  32    sleep 1
  33 done
  34
  35 # Race condition here: if interrupted after the loop but before this
  36 # trap, the lock can be left around.
  37 trap "rmdir $dirname > /dev/null 2>&1" 1 2 3 15
  38
  39 # We have the lock, so run the program.
  40 $program ${1+"$@"}
  41 ret=$?
  42
  43 # Release the lock.
  44 rmdir $dirname > /dev/null 2>&1
  45
  46 exit $ret