Add triggers for adding package update rows

This will be done instead of doing this logic at the application level,
which has some subtle race conditions. When two simultaneous threads
attempt to delete the same package, two update rows for the delete
action are inserted. When done at the database level, we can ensure a
one-to-one mapping between row operations and entries in this table.

Signed-off-by: Dan McGee <dan@archlinux.org>

1 files changed, 45 insertions, 0 deletions

diff --git a/packages/sql/update.postgresql_psycopg2.sql b/packages/sql/update.postgresql_psycopg2.sql
new file mode 100644
index 00000000..6d678387
--- /dev/null
+++ b/packages/sql/update.postgresql_psycopg2.sql
@@ -0,0 +1,45 @@
+CREATE OR REPLACE FUNCTION packages_on_insert() RETURNS trigger AS $body$
+BEGIN
+	INSERT INTO packages_update
+		(action_flag, created, package_id, arch_id, repo_id, pkgname, pkgbase, new_pkgver, new_pkgrel, new_epoch) 
+		VALUES (1, now(), NEW.id, NEW.arch_id, NEW.repo_id, NEW.pkgname, NEW.pkgbase, NEW.pkgver, NEW.pkgrel, NEW.epoch);
+	RETURN NULL;
+END;
+$body$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION packages_on_update() RETURNS trigger AS $body$
+BEGIN
+	INSERT INTO packages_update
+		(action_flag, created, package_id, arch_id, repo_id, pkgname, pkgbase, old_pkgver, old_pkgrel, old_epoch, new_pkgver, new_pkgrel, new_epoch)
+		VALUES (2, now(), NEW.id, NEW.arch_id, NEW.repo_id, NEW.pkgname, NEW.pkgbase, OLD.pkgver, OLD.pkgrel, OLD.epoch, NEW.pkgver, NEW.pkgrel, NEW.epoch);
+	RETURN NULL;
+END;
+$body$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION packages_on_delete() RETURNS trigger AS $body$
+BEGIN
+	INSERT INTO packages_update
+		(action_flag, created, arch_id, repo_id, pkgname, pkgbase, old_pkgver, old_pkgrel, old_epoch)
+		VALUES (3, now(), OLD.arch_id, OLD.repo_id, OLD.pkgname, OLD.pkgbase, OLD.pkgver, OLD.pkgrel, OLD.epoch);
+	RETURN NULL;
+END;
+$body$ LANGUAGE plpgsql;
+
+DROP TRIGGER IF EXISTS packages_insert ON packages;
+CREATE TRIGGER packages_insert
+	AFTER INSERT ON packages
+	FOR EACH ROW
+	EXECUTE PROCEDURE packages_on_insert();
+
+DROP TRIGGER IF EXISTS packages_update ON packages;
+CREATE TRIGGER packages_update
+	AFTER UPDATE ON packages
+	FOR EACH ROW
+	WHEN (OLD.pkgver != NEW.pkgver OR OLD.pkgrel != NEW.pkgrel OR OLD.epoch != NEW.epoch)
+	EXECUTE PROCEDURE packages_on_update();
+
+DROP TRIGGER IF EXISTS packages_delete ON packages;
+CREATE TRIGGER packages_delete
+	AFTER DELETE ON packages
+	FOR EACH ROW
+	EXECUTE PROCEDURE packages_on_delete();