canvas-lms/db/migrate/20151210162949_improve_max_...

57 lines
2.0 KiB
Ruby

class ImproveMaxConcurrent < ActiveRecord::Migration
tag :predeploy
def connection
Delayed::Backend::ActiveRecord::Job.connection
end
def up
if connection.adapter_name == 'PostgreSQL'
search_path = Shard.current.name
execute(<<-CODE)
CREATE OR REPLACE FUNCTION #{connection.quote_table_name('delayed_jobs_after_delete_row_tr_fn')} () RETURNS trigger AS $$
DECLARE
running_count integer;
BEGIN
IF OLD.strand IS NOT NULL THEN
PERFORM pg_advisory_xact_lock(half_md5_as_bigint(OLD.strand));
running_count := (SELECT COUNT(*) FROM delayed_jobs WHERE strand = OLD.strand AND next_in_strand = 't');
IF running_count < OLD.max_concurrent THEN
UPDATE delayed_jobs SET next_in_strand = 't' WHERE id = (
SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT (OLD.max_concurrent - running_count) FOR UPDATE
);
END IF;
END IF;
RETURN OLD;
END;
$$ LANGUAGE plpgsql SET search_path TO #{search_path};
CODE
end
end
def down
if connection.adapter_name == 'PostgreSQL'
search_path = Shard.current.name
execute(<<-CODE)
CREATE OR REPLACE FUNCTION #{connection.quote_table_name('delayed_jobs_after_delete_row_tr_fn')} () RETURNS trigger AS $$
BEGIN
IF OLD.strand IS NOT NULL THEN
PERFORM pg_advisory_xact_lock(half_md5_as_bigint(OLD.strand));
IF (SELECT COUNT(*) FROM delayed_jobs WHERE strand = OLD.strand AND next_in_strand = 't') < OLD.max_concurrent THEN
UPDATE delayed_jobs SET next_in_strand = 't' WHERE id = (
SELECT id FROM delayed_jobs j2 WHERE next_in_strand = 'f' AND
j2.strand = OLD.strand ORDER BY j2.id ASC LIMIT 1 FOR UPDATE
);
END IF;
END IF;
RETURN OLD;
END;
$$ LANGUAGE plpgsql SET search_path TO #{search_path};
CODE
end
end
end