merged from gramsrv upstream

internal/store/allocator.go

@@ -5,10 +5,24 @@ import "context"
 // BoxIDAllocator 分配用户视角 message box id。box_id 允许空洞，但不能回退。
 type BoxIDAllocator interface {
 	NextBoxID(ctx context.Context, userID int64) (int, error)
+	// NextBoxIDs allocates one monotonic id for every distinct user in one
+	// backend batch. Implementations reject invalid users before allocation and
+	// must not turn this operation into a per-user network loop.
+	NextBoxIDs(ctx context.Context, userIDs []int64) (map[int64]int, error)
 	CurrentBoxID(ctx context.Context, userID int64) (int, error)
 }
 
+// DistributedBoxIDAllocator marks an allocator whose per-owner reservations
+// remain atomic across processes and are safe before a PostgreSQL transaction.
+// The private-send microbatch path requires this capability; local and test
+// allocators stay on the single-command transaction path.
+type DistributedBoxIDAllocator interface {
+	BoxIDAllocator
+	DistributedBoxIDAllocation()
+}
+
 // CounterSource 用于 Redis 计数器冷启动时从 PostgreSQL durable log 恢复当前值。
 type CounterSource interface {
 	Current(ctx context.Context, userID int64) (int, error)
+	CurrentBatch(ctx context.Context, userIDs []int64) (map[int64]int, error)
 }