feat(core): optimize performance and reliability through batching and redis-backed unread counts

This commit introduces several significant architectural improvements to enhance system performance, scalability, and reliability:

- **Performance Optimization (N+1 Problem Resolution)**: Implemented batching mechanisms across `MessageHandler`, `ChatService`, `GroupService`, `MessageService`, and `UserService`. This replaces multiple individual database/cache queries with single batch operations for fetching unread counts, last messages, participants, and user information.
- **Enhanced Unread Count Management**: Migrated unread count tracking to a Redis Hash-based approach (`unread#️⃣{userID}`). This allows for atomic increments/decrements and efficient retrieval of both individual conversation unread counts and total unread counts for a user.
- **Improved Message Sequencing**: Integrated Redis-based sequence (`seq`) pre-allocation for messages to ensure strict ordering and reduce database contention during high-concurrency message creation.
- **Push Service Reliability**: Refactored the push notification system to include persistent `PushRecord` tracking. Added a recovery mechanism (`recoverPendingPushes`) to reload pending notifications from the database upon service startup, ensuring better delivery guarantees.
- **WebSocket Reliability**: Updated the WebSocket hub to move away from in-memory history replay in favor of a client-driven synchronization model (`sync_required` event and `ack` handling), reducing memory overhead and improving connection stability.
- **Cache Layer Enhancements**: Added `HIncrBy` and `IncrBySeq` to the `Cache` interface and its implementations (`RedisCache`, `LayeredCache`) to support the new unread and sequence management logic.

internal/handler/message_handler.go

@@ -14,6 +14,76 @@ import (
 	"with_you/internal/service"
 )
 
+// enrichConversations 批量填充会话列表响应数据（解决 N+1 问题）
+func (h *MessageHandler) enrichConversations(ctx context.Context, convs []*model.Conversation, userID string) []*dto.ConversationResponse {
+	if len(convs) == 0 {
+		return nil
+	}
+
+	convIDs := make([]string, len(convs))
+	for i, c := range convs {
+		convIDs[i] = c.ID
+	}
+
+	// 批量查询：4-5 次查询替代 N*5 次
+	unreadCounts, _ := h.chatService.GetUnreadCountBatch(ctx, userID, convIDs)
+	lastMessages, _ := h.chatService.GetLastMessagesBatch(ctx, convIDs)
+	myParticipants, _ := h.messageService.GetMyParticipantsBatch(ctx, convIDs, userID)
+	allParticipants, _ := h.messageService.GetParticipantsBatch(ctx, convIDs)
+
+	// 收集需要额外查询的 ID
+	var groupIDs []string
+	var userIDs []string
+	for _, conv := range convs {
+		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
+			groupIDs = append(groupIDs, *conv.GroupID)
+		}
+	}
+	for _, participants := range allParticipants {
+		for _, p := range participants {
+			if p.UserID != userID {
+				userIDs = append(userIDs, p.UserID)
+			}
+		}
+	}
+
+	memberCounts, _ := h.groupService.GetMemberCountBatch(ctx, groupIDs)
+	usersMap, _ := h.userService.GetUsersByIDs(ctx, userIDs)
+
+	// 组装响应
+	result := make([]*dto.ConversationResponse, len(convs))
+	for i, conv := range convs {
+		unreadCount := unreadCounts[conv.ID]
+		lastMessage := lastMessages[conv.ID]
+
+		myP := myParticipants[conv.ID]
+		isPinned := myP != nil && myP.IsPinned
+		notificationMuted := myP != nil && myP.NotificationMuted
+
+		var resp *dto.ConversationResponse
+		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
+			resp = dto.ConvertConversationToResponse(conv, nil, int(unreadCount), lastMessage, isPinned, notificationMuted)
+			if mc, ok := memberCounts[*conv.GroupID]; ok {
+				resp.MemberCount = int(mc)
+			}
+		} else {
+			participants := allParticipants[conv.ID]
+			var users []*model.User
+			for _, p := range participants {
+				if p.UserID == userID {
+					continue
+				}
+				if u, ok := usersMap[p.UserID]; ok {
+					users = append(users, u)
+				}
+			}
+			resp = dto.ConvertConversationToResponse(conv, users, int(unreadCount), lastMessage, isPinned, notificationMuted)
+		}
+		result[i] = resp
+	}
+	return result
+}
+
 // MessageHandler 消息处理器
 type MessageHandler struct {
 	chatService    service.ChatService
@@ -80,37 +150,8 @@ func (h *MessageHandler) GetConversations(c *gin.Context) {
 		}
 	}
 
-	// 转换为响应格式
-	result := make([]*dto.ConversationResponse, len(filteredConvs))
-	for i, conv := range filteredConvs {
-		// 获取未读数
-		unreadCount, _ := h.chatService.GetUnreadCount(c.Request.Context(), conv.ID, userID)
-
-		// 获取最后一条消息
-		var lastMessage *model.Message
-		messages, _, _ := h.chatService.GetMessages(c.Request.Context(), conv.ID, userID, 1, 1)
-		if len(messages) > 0 {
-			lastMessage = messages[0]
-		}
-
-		// 群聊时返回member_count，私聊时返回participants
-		var resp *dto.ConversationResponse
-		myParticipant, _ := h.getMyConversationParticipant(conv.ID, userID)
-		isPinned := myParticipant != nil && myParticipant.IsPinned
-		notificationMuted := myParticipant != nil && myParticipant.NotificationMuted
-		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
-			// 群聊：实时计算群成员数量
-			memberCount, _ := h.groupService.GetMemberCount(*conv.GroupID)
-			// 创建响应并设置member_count
-			resp = dto.ConvertConversationToResponse(conv, nil, int(unreadCount), lastMessage, isPinned, notificationMuted)
-			resp.MemberCount = memberCount
-		} else {
-			// 私聊：获取参与者信息
-			participants, _ := h.getConversationParticipants(c.Request.Context(), conv.ID, userID)
-			resp = dto.ConvertConversationToResponse(conv, participants, int(unreadCount), lastMessage, isPinned, notificationMuted)
-		}
-		result[i] = resp
-	}
+	// 批量填充会话数据（解决 N+1 问题）
+	result := h.enrichConversations(c.Request.Context(), filteredConvs, userID)
 
 	// 更新 total 为过滤后的数量
 	response.Paginated(c, result, int64(len(filteredConvs)), page, pageSize)
@@ -437,37 +478,8 @@ func (h *MessageHandler) HandleGetConversationList(c *gin.Context) {
 		}
 	}
 
-	// 转换为响应格式
-	result := make([]*dto.ConversationResponse, len(filteredConvs))
-	for i, conv := range filteredConvs {
-		// 获取未读数
-		unreadCount, _ := h.chatService.GetUnreadCount(c.Request.Context(), conv.ID, userID)
-
-		// 获取最后一条消息
-		var lastMessage *model.Message
-		messages, _, _ := h.chatService.GetMessages(c.Request.Context(), conv.ID, userID, 1, 1)
-		if len(messages) > 0 {
-			lastMessage = messages[0]
-		}
-
-		// 群聊时返回member_count，私聊时返回participants
-		var resp *dto.ConversationResponse
-		myParticipant, _ := h.getMyConversationParticipant(conv.ID, userID)
-		isPinned := myParticipant != nil && myParticipant.IsPinned
-		notificationMuted := myParticipant != nil && myParticipant.NotificationMuted
-		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
-			// 群聊：实时计算群成员数量
-			memberCount, _ := h.groupService.GetMemberCount(*conv.GroupID)
-			// 创建响应并设置member_count
-			resp = dto.ConvertConversationToResponse(conv, nil, int(unreadCount), lastMessage, isPinned, notificationMuted)
-			resp.MemberCount = memberCount
-		} else {
-			// 私聊：获取参与者信息
-			participants, _ := h.getConversationParticipants(c.Request.Context(), conv.ID, userID)
-			resp = dto.ConvertConversationToResponse(conv, participants, int(unreadCount), lastMessage, isPinned, notificationMuted)
-		}
-		result[i] = resp
-	}
+	// 批量填充会话数据（解决 N+1 问题）
+	result := h.enrichConversations(c.Request.Context(), filteredConvs, userID)
 
 	response.Paginated(c, result, int64(len(filteredConvs)), page, pageSize)
 }
@@ -1017,37 +1029,8 @@ func (h *MessageHandler) GetConversationsByCursor(c *gin.Context) {
 		}
 	}
 
-	// 转换为响应格式
-	items := make([]*dto.ConversationResponse, len(filteredItems))
-	for i, conv := range filteredItems {
-		// 获取未读数
-		unreadCount, _ := h.chatService.GetUnreadCount(c.Request.Context(), conv.ID, userID)
-
-		// 获取最后一条消息
-		var lastMessage *model.Message
-		messages, _, _ := h.chatService.GetMessages(c.Request.Context(), conv.ID, userID, 1, 1)
-		if len(messages) > 0 {
-			lastMessage = messages[0]
-		}
-
-		// 群聊时返回member_count，私聊时返回participants
-		var resp *dto.ConversationResponse
-		myParticipant, _ := h.getMyConversationParticipant(conv.ID, userID)
-		isPinned := myParticipant != nil && myParticipant.IsPinned
-		notificationMuted := myParticipant != nil && myParticipant.NotificationMuted
-		if conv.Type == model.ConversationTypeGroup && conv.GroupID != nil && *conv.GroupID != "" {
-			// 群聊：实时计算群成员数量
-			memberCount, _ := h.groupService.GetMemberCount(*conv.GroupID)
-			resp = dto.ConvertConversationToResponse(conv, nil, int(unreadCount), lastMessage, isPinned, notificationMuted)
-			resp.MemberCount = memberCount
-		} else {
-			// 私聊：获取参与者信息
-			participants, _ := h.getConversationParticipants(c.Request.Context(), conv.ID, userID)
-			resp = dto.ConvertConversationToResponse(conv, participants, int(unreadCount), lastMessage, isPinned, notificationMuted)
-		}
-		items[i] = resp
-	}
-
+	// 批量填充会话数据（解决 N+1 问题）
+	items := h.enrichConversations(c.Request.Context(), filteredItems, userID)
 	response.Success(c, &dto.ConversationCursorPageResponse{
 		Items:      items,
 		NextCursor: result.NextCursor,

internal/handler/qrcode_handler.go

@@ -53,7 +53,7 @@ func (h *QRCodeHandler) WSEvents(c *gin.Context) {
 		return
 	}
 
-	ch, cancel, replay := h.qrcodeService.GetWSHub().Subscribe(sessionID, 0)
+	ch, cancel := h.qrcodeService.GetWSHub().Subscribe(sessionID, 0)
 	defer cancel()
 
 	w := c.Writer
@@ -82,13 +82,6 @@ func (h *QRCodeHandler) WSEvents(c *gin.Context) {
 		return true
 	}
 
-	// 发送历史事件
-	for _, ev := range replay {
-		if !writeEvent(ev) {
-			return
-		}
-	}
-
 	// 心跳
 	heartbeat := time.NewTicker(25 * time.Second)
 	defer heartbeat.Stop()

internal/handler/ws_handler.go

@@ -140,14 +140,15 @@ func (h *WSHandler) HandleWebSocket(c *gin.Context) {
 	// 3. 创建客户端
 	clientID := atomic.AddUint64(&h.clientSeq, 1)
 	client := &ws.Client{
-		ID:     clientID,
-		UserID: userID,
-		Send:   make(chan []byte, defaultUserBufferSize),
-		Quit:   make(chan struct{}),
+		ID:          clientID,
+		UserID:      userID,
+		Send:        make(chan []byte, defaultUserBufferSize),
+		Quit:        make(chan struct{}),
+		PendingAcks: make(map[string]time.Time),
 	}
 
 	// 4. 注册客户端
-	replayEvents, regErr := h.wsHub.Register(client)
+	regErr := h.wsHub.Register(client)
 	if regErr != nil {
 		zap.L().Warn("WebSocket registration rejected",
 			zap.String("user_id", userID),
@@ -165,23 +166,18 @@ func (h *WSHandler) HandleWebSocket(c *gin.Context) {
 		zap.Uint64("client_id", clientID),
 	)
 
-	// 5. 发送历史回放消息
-	go func() {
-		for _, ev := range replayEvents {
-			msg := ws.ResponseMessage{
-				EventID: ev.ID,
-				Type:    ev.Type,
-				TS:      ev.TS,
-				Payload: ev.Payload,
-			}
-			data, _ := json.Marshal(msg)
-			select {
-			case <-client.Quit:
-				return
-			case client.Send <- data:
-			}
+	// 5. 提示客户端进行 seq 同步
+	syncMsg := ws.ResponseMessage{
+		EventID: h.wsHub.NextID(),
+		Type:    "sync_required",
+		TS:      time.Now().UnixMilli(),
+	}
+	if syncData, err := json.Marshal(syncMsg); err == nil {
+		select {
+		case <-client.Quit:
+		case client.Send <- syncData:
 		}
-	}()
+	}
 
 	// 6. 启动读写goroutine
 	go h.writePump(conn, client)
@@ -322,6 +318,8 @@ func (h *WSHandler) handleMessage(client *ws.Client, msg *ws.Message) {
 		h.handleRead(ctx, client, msg.Payload)
 	case "recall":
 		h.handleRecall(ctx, client, msg.Payload)
+	case "ack":
+		h.handleAck(client, msg.Payload)
 	// 通话信令
 	case "call_invite":
 		h.handleCallInvite(ctx, client, msg.Payload)
@@ -511,6 +509,17 @@ func (h *WSHandler) handleRecall(ctx context.Context, client *ws.Client, payload
 
 const defaultUserBufferSize = 128
 
+// handleAck 处理客户端ACK确认
+func (h *WSHandler) handleAck(client *ws.Client, payload json.RawMessage) {
+	var req struct {
+		MessageID string `json:"message_id"`
+	}
+	if err := json.Unmarshal(payload, &req); err != nil || req.MessageID == "" {
+		return
+	}
+	h.wsHub.AckMessage(client.UserID, req.MessageID)
+}
+
 // isVerified 检查用户是否已通过身份认证
 func (h *WSHandler) isVerified(ctx context.Context, client *ws.Client) bool {
 	user, err := h.userRepo.GetByID(client.UserID)