Fastpath lock collision generator

fastpath_lock_collision.sql

CREATE OR REPLACE FUNCTION int4_to_bytea(int8) RETURNS bytea AS
$BODY$
    SELECT set_byte(' '::bytea, 0, ($1 % 256)::int4) ||
           set_byte(' '::bytea, 0, (($1 / 256) % 256)::int4) ||
           set_byte(' '::bytea, 0, (($1 / 65536) % 256)::int4) ||
           set_byte(' '::bytea, 0, (($1 / 16777216)  % 256)::int4);
$BODY$
LANGUAGE sql;

CREATE OR REPLACE FUNCTION int2_to_bytea(int4) RETURNS bytea AS
$BODY$
    SELECT set_byte(' '::bytea, 0, $1 % 256) ||
           set_byte(' '::bytea, 0, ($1 / 256) % 256);
$BODY$
LANGUAGE sql;

CREATE OR REPLACE FUNCTION hashbytea(bytea) RETURNS int8 AS $$hashvarlena$$ LANGUAGE internal;

CREATE OR REPLACE FUNCTION rellocktaghash(regclass) RETURNS int4 AS
$BODY$
    SELECT (hashbytea(
               int4_to_bytea((SELECT oid FROM pg_database WHERE datname = current_database())::int8) ||
               int4_to_bytea($1::int8) ||
               int4_to_bytea(0) ||
               int2_to_bytea(0) ||
               int2_to_bytea(256)) % 1024)::int4;
$BODY$
LANGUAGE sql;

CREATE OR REPLACE FUNCTION make_collision() RETURNS void AS
$BODY$
BEGIN
    LOOP
        CREATE TABLE collision (i int4);
        IF rellocktaghash('collision'::regclass) = rellocktaghash('pgbench_accounts'::regclass) THEN
            EXIT;
        END IF;
        DROP TABLE collision;
    END LOOP;
END
$BODY$
LANGUAGE plpgsql;