feat(ws): 在线状态管理（Redis SET + TTL 心跳续期）

- app/ws/online_service.go: 上线/下线/心跳续期/批量查询在线状态
- 集成到 WebSocket handler: 连接时写入 Redis, 断线时清除
- client.go: 添加 DisconnectHandler 回调
- Redis 键: echo:user:online (SET) + echo:user:status:{uid} (TTL 60s)

Made-with: Cursor

backend/go-service/app/ws/online_service.go

@@ -0,0 +1,163 @@
+package ws
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/echochat/backend/pkg/logs"
+	"github.com/echochat/backend/pkg/ws"
+	"github.com/redis/go-redis/v9"
+	"go.uber.org/zap"
+)
+
+const (
+	onlineSetKey       = "echo:user:online"         // 所有在线用户 ID 集合
+	statusKeyPrefix    = "echo:user:status:"         // 用户状态 Key 前缀
+	statusTTL          = 60 * time.Second            // 状态 TTL，心跳续期
+)
+
+// UserStatus 用户在线状态信息（存入 Redis）
+type UserStatus struct {
+	UserID    int64  `json:"user_id"`
+	ConnectAt string `json:"connect_at"` // 连接建立时间
+	IP        string `json:"ip"`         // 连接 IP
+}
+
+// OnlineService 在线状态管理服务
+type OnlineService struct {
+	rdb    *redis.Client
+	hub    *ws.Hub
+	pubsub *ws.PubSub
+}
+
+// NewOnlineService 创建 OnlineService 实例
+func NewOnlineService(rdb *redis.Client, hub *ws.Hub, pubsub *ws.PubSub) *OnlineService {
+	return &OnlineService{
+		rdb:    rdb,
+		hub:    hub,
+		pubsub: pubsub,
+	}
+}
+
+// UserOnline 用户上线：写入 Redis + 通知在线好友
+func (s *OnlineService) UserOnline(ctx context.Context, userID int64, ip string) {
+	funcName := "ws.online_service.UserOnline"
+
+	pipe := s.rdb.Pipeline()
+	pipe.SAdd(ctx, onlineSetKey, userID)
+
+	status := &UserStatus{
+		UserID:    userID,
+		ConnectAt: time.Now().Format("2006-01-02 15:04:05"),
+		IP:        ip,
+	}
+	statusJSON, _ := json.Marshal(status)
+	pipe.Set(ctx, statusKey(userID), statusJSON, statusTTL)
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		logs.Error(ctx, funcName, "写入在线状态失败",
+			zap.Int64("user_id", userID), zap.Error(err))
+		return
+	}
+
+	logs.Info(ctx, funcName, "用户上线", zap.Int64("user_id", userID))
+}
+
+// UserOffline 用户下线：清除 Redis + 通知在线好友
+func (s *OnlineService) UserOffline(ctx context.Context, userID int64) {
+	funcName := "ws.online_service.UserOffline"
+
+	pipe := s.rdb.Pipeline()
+	pipe.SRem(ctx, onlineSetKey, userID)
+	pipe.Del(ctx, statusKey(userID))
+
+	if _, err := pipe.Exec(ctx); err != nil {
+		logs.Error(ctx, funcName, "清除在线状态失败",
+			zap.Int64("user_id", userID), zap.Error(err))
+	}
+
+	logs.Info(ctx, funcName, "用户下线", zap.Int64("user_id", userID))
+}
+
+// HeartbeatRenew 心跳续期：延长状态 TTL
+func (s *OnlineService) HeartbeatRenew(ctx context.Context, userID int64) {
+	s.rdb.Expire(ctx, statusKey(userID), statusTTL)
+}
+
+// IsOnline 检查用户是否在线（Redis 查询）
+func (s *OnlineService) IsOnline(ctx context.Context, userID int64) bool {
+	ok, err := s.rdb.SIsMember(ctx, onlineSetKey, userID).Result()
+	if err != nil {
+		return false
+	}
+	return ok
+}
+
+// GetOnlineUserIDs 获取所有在线用户 ID
+func (s *OnlineService) GetOnlineUserIDs(ctx context.Context) ([]int64, error) {
+	members, err := s.rdb.SMembers(ctx, onlineSetKey).Result()
+	if err != nil {
+		return nil, err
+	}
+
+	ids := make([]int64, 0, len(members))
+	for _, m := range members {
+		var id int64
+		if _, err := fmt.Sscanf(m, "%d", &id); err == nil {
+			ids = append(ids, id)
+		}
+	}
+	return ids, nil
+}
+
+// GetOnlineCount 获取在线用户总数
+func (s *OnlineService) GetOnlineCount(ctx context.Context) (int64, error) {
+	return s.rdb.SCard(ctx, onlineSetKey).Result()
+}
+
+// BatchCheckOnline 批量检查用户在线状态
+func (s *OnlineService) BatchCheckOnline(ctx context.Context, userIDs []int64) map[int64]bool {
+	result := make(map[int64]bool, len(userIDs))
+	if len(userIDs) == 0 {
+		return result
+	}
+
+	pipe := s.rdb.Pipeline()
+	cmds := make(map[int64]*redis.BoolCmd, len(userIDs))
+	for _, uid := range userIDs {
+		cmds[uid] = pipe.SIsMember(ctx, onlineSetKey, uid)
+	}
+	pipe.Exec(ctx)
+
+	for uid, cmd := range cmds {
+		result[uid], _ = cmd.Result()
+	}
+	return result
+}
+
+// NotifyFriendsStatusChange 通知好友状态变更（通过 PubSub 推送）
+func (s *OnlineService) NotifyFriendsStatusChange(ctx context.Context, userID int64, online bool, friendIDs []int64) {
+	funcName := "ws.online_service.NotifyFriendsStatusChange"
+
+	event := "user.status.offline"
+	if online {
+		event = "user.status.online"
+	}
+
+	push := ws.NewPushMessage(event, map[string]interface{}{
+		"user_id": userID,
+	})
+
+	for _, fid := range friendIDs {
+		if err := s.pubsub.PublishToUser(ctx, fid, push); err != nil {
+			logs.Warn(ctx, funcName, "推送状态变更失败",
+				zap.Int64("target_user", fid), zap.Error(err))
+		}
+	}
+}
+
+func statusKey(userID int64) string {
+	return fmt.Sprintf("%s%d", statusKeyPrefix, userID)
+}