53 lines
1.8 KiB
Bash
Executable File
53 lines
1.8 KiB
Bash
Executable File
#!/usr/bin/env bash
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# A generic counting semaphore in bash
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# Parameter is the lockfile and operation
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# Setup:
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# rm /tmp/test
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# echo $num > /tmp/test
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set -e
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if [[ $2 = "reset" ]]; then
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if [[ ! "$3" -gt "0" ]]; then echo "Parameter 3: Needs to be a number"; exit;fi
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rm -f $1
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[[ -d "$1_lockdir" ]] && rmdir $1_lockdir
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echo $3 > $1
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exit 0
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fi
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if [[ ! -f $1 ]]; then echo "Parameter 1: File Does not exist"; exit; fi
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if [[ $2 != "lock" ]] && [[ $2 != "release" ]] && [[ $2 != "reset" ]]; then echo "Parameter 2: must be lock, release or reset"; exit; fi
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if [[ $2 = "lock" ]]; then
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SEM=''
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while [[ -z $SEM ]]; do
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if (( $(cat $1 ) == 0 )); then sleep 1; wait; continue; fi
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if mkdir $1_lockdir > /dev/null 2>&1 ; then
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VAL=$(cat $1)
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if (( $VAL > 0 ))
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then
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SEM=$(sed -i "s@$VAL@$(( $VAL - 1))@w /dev/stdout" $1)
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echo "Take $VAL -> $SEM"
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else
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sleep 1; wait
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fi
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else
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sleep 0.5;
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fi
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done
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rmdir $1_lockdir
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else
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SEM=''
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while [[ -z $SEM ]]; do
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if mkdir $1_lockdir > /dev/null 2>&1 ; then
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VAL=$(cat $1)
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SEM=$(sed -i "s@$VAL@$(( $VAL + 1))@w /dev/stdout" $1)
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echo "Give $VAL -> $(( $VAL + 1 ))"
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else
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sleep 0.1;
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fi
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done
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rmdir $1_lockdir
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fi
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#SEM=''; while [[ -z SEM ]]; do VAL=$(cat /tmp/test); if (( $VAL > 0 )); then SEM=$(sed -i "s@$VAL@$(( $VAL - 1))@w /dev/stdout" /tmp/test); else sleep 1; wait; fi; done
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