#!/usr/bin/env bash

## stuckmeter.sh
## Licensed under GPLv3 by Davis Remmel
##
## This program was written to detect when pdftk gets stuck, but it may
## be useful for other processes too. Use it as such:
##     ./stuckmeter.sh pdftk
## to create a file (/tmp/stuckometer-pdftk.pids). The next time this
## program is called, it will compare the previously-collected pids with
## the new ones, and if there exist processes which are the same between
## the two, it will exit with a non-zero code.
##
## Changelog:
##     2018-10-22: Program was written

pname="$1"
if [[ "" == "$pname" ]]
then
    >&2 echo "No process name given"
    exit 1
fi

# Rotate the pidsfiles
oldpidsfile="/tmp/stuckmeter-${pname}.oldpids"
newpidsfile="/tmp/stuckmeter-${pname}.newpids"
touch "$oldpidsfile" "$newpidsfile"
cat "$newpidsfile" > "$oldpidsfile"
pgrep "$pname" > "$newpidsfile"

# Diff the files
matchingpids="$(grep -f "$oldpidsfile" "$newpidsfile" | tr "\n" " ")"
if [[ "" != "$matchingpids" ]]
then
    >&2 echo "Stuck $pname processes: $matchingpids"
    exit 1
fi

echo "No stuck $pname processes"
exit 0