SQL: Add more legacy helpers (#92006)

pkg/storage/legacysql/db.go

@@ -0,0 +1,69 @@
+package legacysql
+
+import (
+	"context"
+	"time"
+
+	"github.com/grafana/grafana/pkg/infra/db"
+	"github.com/grafana/grafana/pkg/services/sqlstore"
+	"github.com/grafana/grafana/pkg/storage/unified/sql/sqltemplate"
+)
+
+// The database may depend on the request context
+type LegacyDatabaseProvider func(ctx context.Context) (*LegacyDatabaseHelper, error)
+
+// NewDatabaseProvider returns a simple provider that always uses the same database implementation
+func NewDatabaseProvider(db db.DB) LegacyDatabaseProvider {
+	helper := &LegacyDatabaseHelper{
+		DB: db,
+		Table: func(n string) string {
+			return n
+		},
+	}
+	return func(ctx context.Context) (*LegacyDatabaseHelper, error) {
+		return helper, nil
+	}
+}
+
+type LegacyDatabaseHelper struct {
+	// The database connection
+	DB db.DB
+
+	// table name locator
+	Table func(n string) string
+}
+
+// Helper to pick the correct dialect
+func (h *LegacyDatabaseHelper) DialectForDriver() sqltemplate.Dialect {
+	if h.DB == nil {
+		return nil
+	}
+	return sqltemplate.DialectForDriver(string(h.DB.GetDBType()))
+}
+
+// Get a resource version from the max value the updated field
+func (h *LegacyDatabaseHelper) GetResourceVersion(ctx context.Context, table string, column string) (int64, error) {
+	table = h.Table(table)
+	column = h.DB.Quote(column)
+
+	var rv int64
+	_ = h.DB.WithDbSession(ctx, func(sess *sqlstore.DBSession) error {
+		v := struct {
+			M time.Time `db:"m"` // xorm date parsing magic
+		}{}
+		ok, err := sess.Table(h.Table(table)).Select("MAX(" + column + ") as m").Get(&v)
+		if ok {
+			rv = v.M.UnixMilli()
+			return nil
+		}
+		return err
+	})
+
+	// When no RV, use a stable non-zero number
+	if rv < 1 {
+		return startup, nil
+	}
+	return rv, nil
+}
+
+var startup = time.Now().UnixMilli()

pkg/storage/legacysql/rv.go

@@ -1,51 +0,0 @@
-package legacysql
-
-import (
-	"context"
-	"time"
-
-	"github.com/grafana/grafana/pkg/infra/db"
-	"github.com/grafana/grafana/pkg/services/sqlstore/migrator"
-)
-
-// The database may depend on the request context
-type NamespacedDBProvider func(ctx context.Context) (db.DB, error)
-
-// Get the list RV from the maximum updated time
-type ResourceVersionLookup = func(ctx context.Context) (int64, error)
-
-// Get a resource version from the max value the updated field
-func GetResourceVersionLookup(sql NamespacedDBProvider, table string, column string) ResourceVersionLookup {
-	return func(ctx context.Context) (int64, error) {
-		db, err := sql(ctx)
-		if err != nil {
-			return 1, err
-		}
-
-		table = db.GetDialect().Quote(table)
-		column = db.GetDialect().Quote(column)
-		switch db.GetDBType() {
-		case migrator.Postgres:
-			max := time.Now()
-			err := db.GetSqlxSession().Get(ctx, &max, "SELECT MAX("+column+") FROM "+table)
-			if err != nil {
-				return 1, nil
-			}
-			return max.UnixMilli(), nil
-		case migrator.MySQL:
-			max := int64(1)
-			_ = db.GetSqlxSession().Get(ctx, &max, "SELECT UNIX_TIMESTAMP(MAX("+column+")) FROM "+table)
-			return max, nil
-		default:
-			// fallthrough to string version
-		}
-
-		max := ""
-		err = db.GetSqlxSession().Get(ctx, &max, "SELECT MAX("+column+") FROM "+table)
-		if err == nil && max != "" {
-			t, _ := time.Parse(time.DateTime, max) // ignore null errors
-			return t.UnixMilli(), nil
-		}
-		return 1, nil
-	}
-}