#!/usr/bin/env bash
# Clean, reproducible knee sweep: ROLLBACK latency vs N at the DEFAULT threshold
# (65536). Fresh file per trial, fresh psql session, R repeats, median reported.
# Only the ROLLBACK is timed (\timing on sits immediately before it).
#
# Self-validating: each trial also prints the file mode AFTER rollback; it must
# equal the committed baseline, proving the undo chain was actually applied. A
# trial where it does not is reported as INVALID rather than silently trusted.
set -u
PORT=${PORT:-5467}
BIN=$HOME/undo-v2-inst/bin
PSQL="$BIN/psql -p $PORT -U postgres -X -q -t -A"
REPEATS=${REPEATS:-5}
NS=${NS:-"100 500 1000 1500 2000 2500 3000 4000 6000 10000 20000"}
THRS=${THRS:-"65536"}
$PSQL -c "CREATE EXTENSION IF NOT EXISTS test_fileops;" >/dev/null 2>&1
median() { sort -n | awk '{a[NR]=$1} END{ if(NR==0){print "NA"} else if(NR%2){print a[(NR+1)/2]} else {printf "%.3f\n",(a[NR/2]+a[NR/2+1])/2} }'; }

# baseline mode we commit before the txn (decimal 420 = 0644, preserved by mask)
BASE=420
echo -e "threshold\tN\trollback_ms_median\ttrials\tvalid"
for thr in $THRS; do
for n in $NS; do
  vals=""; bad=0
  for r in $(seq 1 $REPEATS); do
    out=$($PSQL 2>/dev/null <<SQL
SELECT test_fileops_create_tempfile('knee_${thr}_${n}_${r}.dat') AS f \gset
SELECT test_fileops_chmod(:'f', $BASE);
SET undo_instant_abort_threshold = $thr;
BEGIN;
SELECT count(test_fileops_chmod(:'f',(500+(g%2)*20))) FROM generate_series(1,$n) g;
\timing on
ROLLBACK;
\timing off
SELECT 'MODE=' || test_fileops_get_mode(:'f');
SQL
)
    t=$(printf '%s' "$out" | grep -oE 'Time: [0-9.]+ ms' | tail -1 | grep -oE '[0-9.]+')
    m=$(printf '%s' "$out" | grep -oE 'MODE=[0-9]+' | cut -d= -f2)
    if [ "$m" != "$BASE" ]; then bad=$((bad+1)); fi
    [ -n "$t" ] && vals="${vals}${t}"$'\n'
  done
  med=$(printf '%s' "$vals" | median)
  valid=$([ "$bad" -eq 0 ] && echo yes || echo "NO($bad/$REPEATS)")
  echo -e "$thr\t$n\t$med\t$REPEATS\t$valid"
done
done
echo "=== DONE knee ==="