refactor(backend): 添加 service 缓存端口

backend/internal/repository/gateway_cache.go

@@ -0,0 +1,35 @@
+package repository
+
+import (
+	"context"
+	"time"
+
+	"sub2api/internal/service/ports"
+
+	"github.com/redis/go-redis/v9"
+)
+
+const stickySessionPrefix = "sticky_session:"
+
+type gatewayCache struct {
+	rdb *redis.Client
+}
+
+func NewGatewayCache(rdb *redis.Client) ports.GatewayCache {
+	return &gatewayCache{rdb: rdb}
+}
+
+func (c *gatewayCache) GetSessionAccountID(ctx context.Context, sessionHash string) (int64, error) {
+	key := stickySessionPrefix + sessionHash
+	return c.rdb.Get(ctx, key).Int64()
+}
+
+func (c *gatewayCache) SetSessionAccountID(ctx context.Context, sessionHash string, accountID int64, ttl time.Duration) error {
+	key := stickySessionPrefix + sessionHash
+	return c.rdb.Set(ctx, key, accountID, ttl).Err()
+}
+
+func (c *gatewayCache) RefreshSessionTTL(ctx context.Context, sessionHash string, ttl time.Duration) error {
+	key := stickySessionPrefix + sessionHash
+	return c.rdb.Expire(ctx, key, ttl).Err()
+}