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start data gathering funcs asynchronously to prevent daemon locks

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This commit is contained in:
Thomas Oettli
2024-11-02 00:42:34 +01:00
parent 201456a056
commit ce2daf9749
1 changed files with 43 additions and 12 deletions
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45
snmpd-oid-daemon.sh
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@@ -556,34 +556,65 @@ exec {STDIN}<&0
# Start main in a sub-shell and create a writable fd to it. # Start main in a sub-shell and create a writable fd to it.
echo "daemon starting (PID: $$)" >&$LOG echo "daemon starting (PID: $$)" >&$LOG
exec {DATAIN}> >(main) exec {DATAIN}> >(main)
pid=$! main_pid=$!
trap "echo daemon stopped >&$LOG" EXIT trap "echo daemon stopped >&$LOG" EXIT
declare -A timetable declare -A timetable
declare -A fdtable
declare -A pidtable
first_run=true first_run=true
while :; do while :; do
# Check if main is still alive and exit otherwise. # Check if main is still alive and exit otherwise.
ps -p $pid > /dev/null || break ps -p $main_pid > /dev/null || break
[ -v EPOCHSECONDS ] && now=$EPOCHSECONDS || now=$(date +%s) [ -v EPOCHSECONDS ] && now=$EPOCHSECONDS || now=$(date +%s)
for func in "${!DATA_FUNCS[@]}"; do for func in "${!DATA_FUNCS[@]}"; do
next_update=${timetable[$func]:-$now} next_update=${timetable[$func]:-$now}
if (( now >= next_update )); then if (( now >= next_update )); then
delay=${DATA_FUNCS[$func]} delay=${DATA_FUNCS[$func]}
$first_run && echo "starting $func (refresh every $delay seconds)" >&$LOG
fd=${fdtable[$func]:--1}
if (( fd == -1 )); then
exec {data}< <($func </dev/null)
pid=$!
echo "gathering: executed $func (PID $pid, FD $data)" >&$DEBUGLOG
fdtable[$func]=$data
pidtable[$func]=$pid
else
pid=${pidtable[$func]}
echo "gathering: skip executing $func, it is still running (PID $pid, FD $fd)" >&2
fi
((next_update+=delay)) ((next_update+=delay))
timetable[$func]=$next_update timetable[$func]=$next_update
$first_run && echo "starting $func (refresh every $delay seconds)" >&$LOG echo "gathering: scheduled next execution of $func at $(date -d @$next_update)" >&$DEBUGLOG
echo "gathering: executing $func" >&$DEBUGLOG fi
data=$($func </dev/null) done
for func in "${!fdtable[@]}"; do
fd=${fdtable[$func]}
(( fd == -1 )) && continue
if ! $first_run; then
read -t 0 -u $fd
(( $? == 0 )) || continue
fi
data=$(timeout 1 cat <&$fd)
rc=$? rc=$?
echo "gathering: $func exited (rc=$rc), schedule next refresh at $(date -d @$next_update)" >&$DEBUGLOG pid=${pidtable[$func]}
if (( rc == 124 )); then
echo "gathering: timeout receiving data from $func (PID $pid, FD $fd), killing process" >&2
kill -9 $pid
fi
wait $pid
rc=$?
echo "gathering: $func exited (rc = $rc)" >&$DEBUGLOG
eval "exec $fd>&-"
fdtable[$func]=-1
if (( rc == 0 )) && [ -n "$data" ]; then if (( rc == 0 )) && [ -n "$data" ]; then
echo "gathering: sending data to main" >&$DEBUGLOG echo "gathering: sending data to main" >&$DEBUGLOG
echo "$data" 1>&$DATAIN echo "$data" 1>&$DATAIN
echo "ENDOFDATA" >&$DATAIN echo "ENDOFDATA" >&$DATAIN
fi fi
fi
done done
# Emit STARTUPDONE to inform main about data availibity from all gatherin functions (warmup). # Emit STARTUPDONE to inform main about data availibity from all gatherin functions (warmup).