#!/usr/bin/env bash
# Show blocks_done / blocks_total of pg_stat_progress_create_index while
# CREATE INDEX CONCURRENTLY and REINDEX CONCURRENTLY wait after their
# validation scan.
#
# usage: bash repro-f3.sh.txt <bindir> [port]
#   <bindir> holds initdb, pg_ctl and psql of the build under test.
#
# A throwaway cluster is created in a temporary directory and removed at
# the end.  The waits are made by plain sessions:
#   CIC:     a REPEATABLE READ transaction opened before the command
#            ("waiting for old snapshots").
#   REINDEX: the same, then two transactions that read the table, each
#            opened while the previous wait is in progress ("waiting for
#            readers before marking dead", "... before dropping").
# Each wait is sampled 5 times, 1 second apart; it lasts as long as the
# session that causes it stays open.
set -u
BIN=${1:?usage: repro-f3.sh.txt <bindir> [port]}
PORT=${2:-54329}
D=$(mktemp -d "${TMPDIR:-/tmp}/repro-f3.XXXXXX")
trap 'touch "$D"/release-h1 "$D"/release-h2 "$D"/release-h3; sleep 0.5;
      "$BIN"/pg_ctl -D "$D/data" -m immediate stop >/dev/null 2>&1; rm -rf "$D"' EXIT

"$BIN"/initdb -D "$D/data" -A trust --no-sync >"$D/initdb.log" 2>&1 ||
  { cat "$D/initdb.log"; exit 1; }
"$BIN"/pg_ctl -D "$D/data" -l "$D/server.log" -w \
  -o "-p $PORT -c listen_addresses='' -c unix_socket_directories='$D'" \
  start >/dev/null || { cat "$D/server.log"; exit 1; }

q() { "$BIN"/psql -X -At -h "$D" -p "$PORT" -d postgres -c "$1"; }

# hold <name> <sql>: run <sql> in a new transaction and keep it open until
# $D/release-<name> exists.
hold() {
  rm -f "$D/release-$1"
  { printf 'BEGIN ISOLATION LEVEL REPEATABLE READ;\n%s\n' "$2"
    while [ ! -e "$D/release-$1" ]; do sleep 0.1; done
    echo 'COMMIT;'
  } | PGAPPNAME=$1 "$BIN"/psql -X -q -h "$D" -p "$PORT" -d postgres \
      >/dev/null &
  for _ in $(seq 100); do
    [ "$(q "SELECT count(*) FROM pg_stat_activity
            WHERE application_name = '$1'
              AND state = 'idle in transaction'")" = 1 ] && return 0
    sleep 0.1
  done
  echo "session $1 did not start"; exit 1
}

PROGRESS="SELECT phase, blocks_done, blocks_total
          FROM pg_stat_progress_create_index WHERE relid = 't'::regclass"

wait_phase() {
  for _ in $(seq 600); do
    [ "$(q "$PROGRESS" | cut -d'|' -f1)" = "$1" ] && return 0
    sleep 0.1
  done
  echo "phase '$1' not reached"; q "$PROGRESS"; exit 1
}

SHORT=0; FULL=0
sample() {
  for i in 1 2 3 4 5; do
    IFS='|' read -r ph done total <<<"$(q "$PROGRESS")"
    echo "$1 sample $i: phase=\"$ph\" blocks_done=$done blocks_total=$total"
    if [ "$done" = "$total" ]; then FULL=$((FULL + 1)); else SHORT=$((SHORT + 1)); fi
    [ $i -lt 5 ] && sleep 1
  done
}

q "CREATE TABLE t (a int) WITH (autovacuum_enabled = off);
   INSERT INTO t SELECT g FROM generate_series(1, 100000) g;" >/dev/null
echo "table t: $(q "SELECT pg_relation_size('t') / current_setting('block_size')::int") blocks"

# CREATE INDEX CONCURRENTLY
hold h1 'SELECT 1;'
q 'CREATE INDEX CONCURRENTLY t_a ON t (a);' >/dev/null &
CMD=$!
wait_phase 'waiting for old snapshots'
sample cic
touch "$D/release-h1"; wait $CMD

# REINDEX CONCURRENTLY
hold h1 'SELECT 1;'
q 'REINDEX INDEX CONCURRENTLY t_a;' >/dev/null &
CMD=$!
wait_phase 'waiting for old snapshots'
sample reindex
hold h2 'SELECT count(*) FROM t;'
touch "$D/release-h1"
wait_phase 'waiting for readers before marking dead'
sample reindex
hold h3 'SELECT count(*) FROM t;'
touch "$D/release-h2"
wait_phase 'waiting for readers before dropping'
sample reindex
touch "$D/release-h3"; wait $CMD

echo "RESULT: $SHORT samples with blocks_done < blocks_total," \
     "$FULL with blocks_done = blocks_total"