Bash: Kill Process after timeout or after an event - bash

Question

I have a script which runs a long running process.
This process is currently stopped after a timeout.
#!/bin/bash
timeout 3600 ./longrunningprocess
My problem is now that this process does not return before the timeout is reached and sometimes I need to stop it earlier.
What do I need?
I want to start some other script in parallel which checks periodically if my longrunningprocess should stop. When this bash script returns, the timeout command should be killed.
Any idea how I could achieve that?
Is there anything like the timeout command? Not with a timespan but a script I could start and which is like the event trigger?
E.g.
#!/bin/bash
fancyCommandKillsSecondCommandIfFirstCommandReturns "./myPeriodicScript.sh" "timeout 3600 ./longrunningprocess"
Thanks!
Edit: Something like "Start 2 Processes in parallel and kill both if one returns" would also work...
Edit2: The answers gave me some ideas for a script:
#!/bin/bash
FirstProcess="${1}"
SecondProcess="${2}"
exec $FirstProcess &
PID1=$!
exec $SecondProcess &
PID2=$!
function killall {
if ps -p $PID1 > /dev/null
then
kill -9 $PID1
fi
if ps -p $PID2 > /dev/null
then
kill -9 $PID2
fi
}
trap killall EXIT
while true; do
if ! ps -p $PID1 > /dev/null
then
exit;
fi
if ! ps -p $PID2 > /dev/null
then
exit;
fi
sleep 5;
done
This kind of does what I want. Is there any native functionality or a better way to do this?

Answer 1

Start the longrunningprocess in the background and remember the pid.
#!/bin/bash
timeout 3600 ./longrunningprocess &
long_pid=$!
./myPeriodicScript.sh
kill -9 ${long_pid}

Answer 2

If you parse the output of the longrunningprocess to determine if the process needs to be killed, then you could do something like this:
#!/bin/bash
FIFO="tmpfifo"
TIMEOUT=10
mkfifo $FIFO
timeout 100 ./longrun &> $FIFO &
PID=$!
while read line; do
echo "Parsing $line see if $PID needs to be killed";
if [ "$line" = "5" ]; then
kill $PID
fi
done < $FIFO
exit
This will pipe all output into a FIFO and start reading from that fifo. In addition, it keeps the PID of the timeout process, so it can be killed.