From b5141d6a709634a1153c0613ac099aba8c4fde0d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ask=20Bj=C3=B8rn=20Hansen?= <ask@develooper.com>
Date: Sat, 12 Jul 2025 13:57:27 -0700
Subject: [PATCH] Add database transaction helpers

---
 database/transaction.go | 68 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 database/transaction.go

diff --git a/database/transaction.go b/database/transaction.go
new file mode 100644
index 0000000..45743a1
--- /dev/null
+++ b/database/transaction.go
@@ -0,0 +1,68 @@
+package database
+
+import (
+	"context"
+	"fmt"
+
+	"go.ntppool.org/common/logger"
+)
+
+// DB interface for database operations that can begin transactions
+type DB[Q any] interface {
+	Begin(ctx context.Context) (Q, error)
+}
+
+// TX interface for transaction operations
+type TX interface {
+	Commit(ctx context.Context) error
+	Rollback(ctx context.Context) error
+}
+
+// WithTransaction executes a function within a database transaction
+// Handles proper rollback on error and commit on success
+func WithTransaction[Q TX](ctx context.Context, db DB[Q], fn func(ctx context.Context, q Q) error) error {
+	tx, err := db.Begin(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to begin transaction: %w", err)
+	}
+
+	var committed bool
+	defer func() {
+		if !committed {
+			if rbErr := tx.Rollback(ctx); rbErr != nil {
+				// Log rollback error but don't override original error
+				log := logger.FromContext(ctx)
+				log.ErrorContext(ctx, "failed to rollback transaction", "error", rbErr)
+			}
+		}
+	}()
+
+	if err := fn(ctx, tx); err != nil {
+		return err
+	}
+
+	if err := tx.Commit(ctx); err != nil {
+		return fmt.Errorf("failed to commit transaction: %w", err)
+	}
+
+	committed = true
+	return nil
+}
+
+// WithReadOnlyTransaction executes a read-only function within a transaction
+// Always rolls back at the end (for consistent read isolation)
+func WithReadOnlyTransaction[Q TX](ctx context.Context, db DB[Q], fn func(ctx context.Context, q Q) error) error {
+	tx, err := db.Begin(ctx)
+	if err != nil {
+		return fmt.Errorf("failed to begin read-only transaction: %w", err)
+	}
+
+	defer func() {
+		if rbErr := tx.Rollback(ctx); rbErr != nil {
+			log := logger.FromContext(ctx)
+			log.ErrorContext(ctx, "failed to rollback read-only transaction", "error", rbErr)
+		}
+	}()
+
+	return fn(ctx, tx)
+}