stores: fix deadlock in RefreshHealth

stores/metadata.go

@@ -1961,8 +1961,8 @@ func (s *SQLStore) RefreshHealth(ctx context.Context) error {
 	// Update slab health in batches.
 	now := time.Now()
 
-	for {
-		healthQuery := s.db.Raw(`
+	// build health query
+	healthQuery := s.db.Raw(`
 SELECT slabs.id, slabs.db_contract_set_id, CASE WHEN (slabs.min_shards = slabs.total_shards)
 THEN
     CASE WHEN (COUNT(DISTINCT(CASE WHEN cs.name IS NULL THEN NULL ELSE c.host_id END)) < slabs.min_shards)
@@ -1981,50 +1981,37 @@ WHERE slabs.health_valid_until <= ?
 GROUP BY slabs.id
 LIMIT ?
 `, now.Unix(), refreshHealthBatchSize)
+
+	for {
 		var rowsAffected int64
 		err := s.retryTransaction(func(tx *gorm.DB) error {
-			// create temp table from the health query since we will reuse it
-			if err := tx.Exec("DROP TABLE IF EXISTS src").Error; err != nil {
-				return err
-			} else if err = tx.Exec("CREATE TEMPORARY TABLE src AS ?", healthQuery).Error; err != nil {
-				return err
-			} else if err = tx.Exec("CREATE INDEX src_id ON src (id)").Error; err != nil {
-				return err
-			}
-
 			var res *gorm.DB
 			if isSQLite(s.db) {
-				res = tx.Exec("UPDATE slabs SET health = src.health, health_valid_until = (?) FROM src WHERE slabs.id=src.id", sqlRandomTimestamp(s.db, now, refreshHealthMinHealthValidity, refreshHealthMaxHealthValidity))
+				res = tx.Exec("UPDATE slabs SET health = inner.health, health_valid_until = (?) FROM (?) AS inner WHERE slabs.id=inner.id", sqlRandomTimestamp(s.db, now, refreshHealthMinHealthValidity, refreshHealthMaxHealthValidity), healthQuery)
 			} else {
-				res = tx.Exec("UPDATE slabs sla INNER JOIN src h ON sla.id = h.id SET sla.health = h.health, health_valid_until = (?)", sqlRandomTimestamp(s.db, now, refreshHealthMinHealthValidity, refreshHealthMaxHealthValidity))
+				res = tx.Exec("UPDATE slabs sla INNER JOIN (?) h ON sla.id = h.id SET sla.health = h.health, health_valid_until = (?)", healthQuery, sqlRandomTimestamp(s.db, now, refreshHealthMinHealthValidity, refreshHealthMaxHealthValidity))
 			}
 			if res.Error != nil {
 				return res.Error
 			}
 			rowsAffected = res.RowsAffected
 
-			// Update the health of the objects associated with the updated slabs.
-			if isSQLite(s.db) {
-				return tx.Exec(`UPDATE objects SET health = i.health FROM (
-									SELECT slices.db_object_id, MIN(s.health) AS health
-									FROM slices
-									INNER JOIN src s ON s.id = slices.db_slab_id
-									INNER JOIN objects o ON o.id = slices.db_object_id
-									GROUP BY slices.db_object_id
-								) i
-								WHERE i.db_object_id = objects.id AND objects.health != i.health`).Error
-			} else {
-				return tx.Exec(`UPDATE objects
-								INNER JOIN (
-									SELECT slices.db_object_id, MIN(s.health) as health
-									FROM slices
-									INNER JOIN src s ON s.id = slices.db_slab_id
-									GROUP BY slices.db_object_id
-								) i ON objects.id = i.db_object_id
-								SET objects.health = i.health
-								WHERE objects.health != i.health
-								`).Error
-			}
+			// Update the health of objects with outdated health.
+			return tx.Exec(`
+			UPDATE objects
+			SET health = (
+				SELECT MIN(slabs.health)
+				FROM slabs
+				INNER JOIN slices ON slices.db_slab_id = slabs.id
+				INNER JOIN objects ON slices.db_object_id = objects.id
+			)
+			WHERE EXISTS (
+				SELECT 1 FROM slabs
+				INNER JOIN slices ON slices.db_slab_id = slabs.id
+				INNER JOIN objects ON slices.db_object_id = objects.id
+				WHERE slabs.health < objects.health
+			)	
+			`).Error
 		})
 		if err != nil {
 			return err