Refactor shortpath (again) and remove the transaction wrapper from th…

…e database

database.go

@@ -24,7 +24,7 @@ type database struct {
 	// Other things
 	pc    singleflightx.Group[string, []byte] // persistant cache
 	pcm   sync.RWMutex                        // post creation
-	sp    sync.Mutex                          // short path creation
+	sp    singleflightx.Group[string, string] // short path creation
 	debug bool
 }
 
@@ -200,64 +200,6 @@ func (db *database) QueryRowContext(ctx context.Context, query string, args ...a
 	return db.readDb.QueryRowContext(ctx, query, args...), nil
 }
 
-type transaction struct {
-	tx *sql.Tx
-	db *database
-}
-
-func (db *database) Begin() (*transaction, error) {
-	return db.BeginTx(context.Background(), nil)
-}
-
-func (db *database) BeginTx(ctx context.Context, opts *sql.TxOptions) (*transaction, error) {
-	if db == nil || db.writeDb == nil {
-		return nil, errors.New("database not initialized")
-	}
-	tx, err := db.writeDb.BeginTx(ctx, opts)
-	if err != nil {
-		return nil, err
-	}
-	return &transaction{tx: tx, db: db}, nil
-}
-
-func (tx *transaction) Exec(query string, args ...any) (sql.Result, error) {
-	return tx.ExecContext(context.Background(), query, args...)
-}
-
-func (tx *transaction) ExecContext(ctx context.Context, query string, args ...any) (sql.Result, error) {
-	ctx = tx.db.dbBefore(ctx, query, args...)
-	defer tx.db.dbAfter(ctx, query, args...)
-	return tx.tx.ExecContext(ctx, query, args...)
-}
-
-func (tx *transaction) Query(query string, args ...any) (*sql.Rows, error) {
-	return tx.QueryContext(context.Background(), query, args...)
-}
-
-func (tx *transaction) QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) {
-	ctx = tx.db.dbBefore(ctx, query, args...)
-	defer tx.db.dbAfter(ctx, query, args...)
-	return tx.tx.QueryContext(ctx, query, args...)
-}
-
-func (tx *transaction) QueryRow(query string, args ...any) *sql.Row {
-	return tx.QueryRowContext(context.Background(), query, args...)
-}
-
-func (tx *transaction) QueryRowContext(ctx context.Context, query string, args ...any) *sql.Row {
-	ctx = tx.db.dbBefore(ctx, query, args...)
-	defer tx.db.dbAfter(ctx, query, args...)
-	return tx.tx.QueryRowContext(ctx, query, args...)
-}
-
-func (tx *transaction) Commit() error {
-	return tx.tx.Commit()
-}
-
-func (tx *transaction) Rollback() error {
-	return tx.tx.Rollback()
-}
-
 func (db *database) dump(file string) {
 	if db == nil || db.readDb == nil {
 		return

shortPath.go

@@ -10,31 +10,41 @@ func (db *database) shortenPath(p string) (string, error) {
 	if p == "" {
 		return "", errors.New("empty path")
 	}
-
-	db.sp.Lock()
-	defer db.sp.Unlock()
-
-	result, err := db.shortenPathTransaction(p)
-	if err != nil {
+	result, err, _ := db.sp.Do(p, func() (string, error) {
+		sp, err := db.queryShortPath(p)
+		if err == nil && sp != "" {
+			return sp, nil
+		} else if !errors.Is(err, sql.ErrNoRows) {
+			return "", err
+		}
+		// In case it wasn't shortened yet ...
+		err = db.createShortPath(p)
+		if err != nil {
+			return "", err
+		}
+		// Query again
+		sp, err = db.queryShortPath(p)
+		if err == nil && sp != "" {
+			return sp, nil
+		}
 		return "", err
-	}
-
-	return result, nil
+	})
+	return result, err
 }
 
-func (db *database) shortenPathTransaction(p string) (string, error) {
-	tx, err := db.Begin()
+func (db *database) queryShortPath(p string) (string, error) {
+	row, err := db.QueryRow("select id from shortpath where path = @path", sql.Named("path", p))
 	if err != nil {
 		return "", err
 	}
-	defer tx.Rollback()
-
 	var id int64
-	err = tx.QueryRow("select id from shortpath where path = @path", sql.Named("path", p)).Scan(&id)
-	if err == sql.ErrNoRows {
-		// Path doesn't exist, insert new entry with the lowest available id
-		err = tx.QueryRow(`
-            WITH RECURSIVE ids(n) AS (
+	err = row.Scan(&id)
+	return fmt.Sprintf("/s/%x", id), err
+}
+
+func (db *database) createShortPath(p string) error {
+	_, err := db.Exec(`
+			WITH RECURSIVE ids(n) AS (
                 SELECT 1
                 UNION ALL
                 SELECT n + 1 FROM ids
@@ -48,19 +58,6 @@ func (db *database) shortenPathTransaction(p string) (string, error) {
                  ORDER BY n
                  LIMIT 1),
                 ?
-            )
-            RETURNING id
-        `, p).Scan(&id)
-		if err != nil {
-			return "", err
-		}
-	} else if err != nil {
-		return "", err
-	}
-
-	if err = tx.Commit(); err != nil {
-		return "", err
-	}
-
-	return fmt.Sprintf("/s/%x", id), nil
+            )`, p)
+	return err
 }