-- 0.20.0 (fourth review): a pinned call (_render, brief, verify, ...) reads the session's settings and cursors once,
-- into a pin. When the call ended in an error caught by a savepoint, its pin stayed behind: pins were cleared only
-- when a transaction aborted, never when it committed, and a pin was taken as current while a subtransaction with
-- its id was open. Subtransaction ids start over in every transaction, so the watch trigger of a later write inside
-- a savepoint took that pin, whose lists were in memory already freed: it read garbage and the server restarted
-- (signal 11), or it read the old lists and rendered with the writer's own settings. A writer with INSERT on a
-- watched table could restart the server. Against 7f37426 this file ends the backend at its first INSERT.
\set VERBOSITY terse

CREATE EXTENSION pg_phasevec;
SELECT phasevec.reader_register($n$r1$n$, repeat($h$a$h$, 64), 4) > 0 AS r1;
CREATE TABLE pin_flag (boom boolean);
INSERT INTO pin_flag VALUES (false);
CREATE TABLE pin_docs (id int PRIMARY KEY, body text);
INSERT INTO pin_docs SELECT g, $t$doc $t$ || g FROM generate_series(1, 50) g;
-- the recipe prints a custom setting (a render runs at every setting's default: it must print nothing) and fails
-- while the flag is up
CREATE FUNCTION pin_rec(b text) RETURNS text LANGUAGE sql STABLE AS $f$
    SELECT b || ' mode=' || coalesce(current_setting('app.mode', true), '')
           || CASE WHEN (SELECT boom FROM public.pin_flag) THEN (1 / (SELECT 0))::text ELSE '' END
$f$;
SELECT phasevec.watch($w$pin_docs$w$, $w$pin_docs$w$::regclass, $k$id$k$, $r$public.pin_rec(r.body)$r$, $n$r1$n$) > 0
    AS watch;
-- what the watch noted for a key, against the text a render at the defaults gives
CREATE FUNCTION pin_noted(k text, b text) RETURNS boolean LANGUAGE sql AS $f$
    SELECT s.text_hash = sha256(convert_to(b || ' mode=', 'UTF8'))
      FROM phasevec.sources s JOIN phasevec.watches w ON w.id = s.watch
     WHERE w.name = 'pin_docs' AND s.key = k
$f$;
-- settings off their default: the pin's list of them is long, and its freed memory is soon someone else's
SELECT count(set_config($s$app.p$s$ || g, $v$v$v$, false)) FROM generate_series(1, 200) g;

-- (1) the render fails inside its pin; the savepoint catches it; the transaction commits
UPDATE pin_flag SET boom = true;
BEGIN;
SAVEPOINT s;
SELECT count(*) FROM phasevec._render($w$pin_docs$w$, NULL);
ROLLBACK TO s;
COMMIT;
UPDATE pin_flag SET boom = false;
-- a later transaction writes inside a savepoint (subtransaction id 2 again), with a setting of its own
BEGIN;
SET LOCAL app.mode = 'writer';
SAVEPOINT s;
INSERT INTO pin_docs VALUES (101, $t$after a caught render$t$);
RELEASE s;
COMMIT;
SELECT pin_noted($k$101$k$, $t$after a caught render$t$) AS rendered_at_defaults;

-- (2) the same, caught by a PL/pgSQL exception block
UPDATE pin_flag SET boom = true;
DO $d$
BEGIN
    PERFORM count(*) FROM phasevec._render('pin_docs', NULL);
EXCEPTION WHEN division_by_zero THEN
    RAISE NOTICE 'caught: %', SQLERRM;
END $d$;
UPDATE pin_flag SET boom = false;
BEGIN;
SET LOCAL app.mode = 'writer';
SAVEPOINT a;
SAVEPOINT b;
UPDATE pin_docs SET body = $t$after a caught block$t$ WHERE id = 1;
COMMIT;
SELECT pin_noted($k$1$k$, $t$after a caught block$t$) AS rendered_at_defaults;

-- (3) in the same transaction: the savepoint that caught it is gone, and the next one is not it
UPDATE pin_flag SET boom = true;
BEGIN;
SAVEPOINT s;
SELECT count(*) FROM phasevec._render($w$pin_docs$w$, NULL);
ROLLBACK TO s;
UPDATE pin_flag SET boom = false;
SET LOCAL app.mode = 'writer';
SAVEPOINT s;
INSERT INTO pin_docs VALUES (102, $t$same transaction$t$);
COMMIT;
SELECT pin_noted($k$102$k$, $t$same transaction$t$) AS rendered_at_defaults;

-- (4) many times over: every caught failure leaves nothing behind
UPDATE pin_flag SET boom = true;
DO $d$
BEGIN
    FOR i IN 1 .. 40 LOOP
        BEGIN
            PERFORM count(*) FROM phasevec._render('pin_docs', NULL);
        EXCEPTION WHEN division_by_zero THEN NULL;
        END;
    END LOOP;
END $d$;
UPDATE pin_flag SET boom = false;
BEGIN;
SET LOCAL app.mode = 'writer';
SAVEPOINT a;
SAVEPOINT b;
SAVEPOINT c;
INSERT INTO pin_docs SELECT g, $t$burst $t$ || g FROM generate_series(200, 260) g;
COMMIT;
SELECT count(*) FILTER (WHERE pin_noted(g::text, $t$burst $t$ || g)) AS rendered_at_defaults
  FROM generate_series(200, 260) g;
-- and a pinned call that ends well still renders at the defaults
SET app.mode = 'caller';
SELECT count(*) FILTER (WHERE body LIKE '% mode=') AS at_defaults, count(*) AS rows
  FROM phasevec._render($w$pin_docs$w$, NULL);
RESET app.mode;

DROP TABLE pin_docs, pin_flag;
DROP FUNCTION pin_rec(text), pin_noted(text, text);
DROP EXTENSION pg_phasevec;