35 lines
773 B
Bash
35 lines
773 B
Bash
#! /bin/sh
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# Shell-based mutex using mkdir.
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lockdir="$1" prog="$2"; shift 2 || exit 1
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# Remember when we started trying to acquire the lock.
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count=0
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touch lock-stamp.$$
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trap 'rm -r "$lockdir" lock-stamp.$$' 0
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until mkdir "$lockdir" 2>/dev/null; do
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# Say something periodically so the user knows what's up.
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if [ `expr $count % 30` = 0 ]; then
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# Reset if the lock has been renewed.
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if [ -n "`find \"$lockdir\" -newer lock-stamp.$$`" ]; then
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touch lock-stamp.$$
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count=1
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# Steal the lock after 5 minutes.
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elif [ $count = 300 ]; then
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echo removing stale $lockdir >&2
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rm -r "$lockdir"
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else
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echo waiting to acquire $lockdir >&2
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fi
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fi
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sleep 1
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count=`expr $count + 1`
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done
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echo $prog "$@"
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$prog "$@"
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# The trap runs on exit.
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