fix: broadcast offline presence as soon as the last session drops

Logout left contacts seeing the user online until the me topic idle timeout
fired presUsersOfInterest(off), and even that frame was silently dropped
for p2p routes by handlePresence's xoriginal check. MarkUserOffline now
returns the remaining session count and cleanUp notifies users of interest
immediately once it hits zero; p2p presence is delivered straight to the
contact's me topic, mirroring presSingleUserOffline. Zentao #22.

server/store/group_message_runtime.go

@@ -109,7 +109,7 @@ type groupMessageRuntime interface {
 	InvalidateHotMessages(tenantID types.TenantID, topic string, ranges []types.Range) error
 	MarkUserOnline(tenantID types.TenantID, uid types.Uid, sid, nodeID, device, userAgent string) error
 	RefreshUserPresence(tenantID types.TenantID, uid types.Uid, sid, nodeID string) error
-	MarkUserOffline(tenantID types.TenantID, uid types.Uid, sid, nodeID string) error
+	MarkUserOffline(tenantID types.TenantID, uid types.Uid, sid, nodeID string) (int, error)
 	GetUserPresence(tenantID types.TenantID, uid types.Uid) (*UserPresence, error)
 	MarkTopicMemberOnline(tenantID types.TenantID, topic string, uid types.Uid, nodeID string) error
 	MarkTopicMemberOffline(tenantID types.TenantID, topic string, uid types.Uid, nodeID string) error
@@ -300,9 +300,9 @@ func RefreshUserPresence(tenantID types.TenantID, uid types.Uid, sid, nodeID str
 	return groupMsgRuntime.RefreshUserPresence(tenantID, uid, sid, nodeID)
 }
 
-func MarkUserOffline(tenantID types.TenantID, uid types.Uid, sid, nodeID string) error {
+func MarkUserOffline(tenantID types.TenantID, uid types.Uid, sid, nodeID string) (int, error) {
 	if groupMsgRuntime == nil || !tenantID.IsValid() || uid.IsZero() || sid == "" {
-		return nil
+		return 0, nil
 	}
 	return groupMsgRuntime.MarkUserOffline(tenantID, uid, sid, nodeID)
 }
@@ -939,7 +939,7 @@ func (r *redisGroupMessageRuntime) RefreshUserPresence(tenantID types.TenantID,
 	return err
 }
 
-func (r *redisGroupMessageRuntime) MarkUserOffline(tenantID types.TenantID, uid types.Uid, sid, nodeID string) error {
+func (r *redisGroupMessageRuntime) MarkUserOffline(tenantID types.TenantID, uid types.Uid, sid, nodeID string) (int, error) {
 	if nodeID == "" {
 		nodeID = "local"
 	}
@@ -956,11 +956,11 @@ func (r *redisGroupMessageRuntime) MarkUserOffline(tenantID types.TenantID, uid
 	pipe.SRem(ctx, sessionsKey, member)
 	pipe.SRem(ctx, nodeKey, uid.UserId())
 	if _, err := pipe.Exec(ctx); err != nil {
-		return err
+		return 0, err
 	}
 	count, err := r.client.SCard(ctx, sessionsKey).Result()
 	if err != nil {
-		return err
+		return 0, err
 	}
 	if count > 0 {
 		pipe = r.client.Pipeline()
@@ -968,14 +968,14 @@ func (r *redisGroupMessageRuntime) MarkUserOffline(tenantID types.TenantID, uid
 		pipe.Expire(ctx, userKey, ttl)
 		pipe.Expire(ctx, sessionsKey, ttl)
 		_, err = pipe.Exec(ctx)
-		return err
+		return int(count), err
 	}
 	pipe = r.client.Pipeline()
 	pipe.HSet(ctx, userKey, "online", "0", "session_count", 0, "node_id", nodeID, "last_seen_at", now.Format(time.RFC3339Nano))
 	pipe.Expire(ctx, userKey, ttl)
 	pipe.Del(ctx, sessionsKey)
 	_, err = pipe.Exec(ctx)
-	return err
+	return 0, err
 }
 
 func (r *redisGroupMessageRuntime) GetUserPresence(tenantID types.TenantID, uid types.Uid) (*UserPresence, error) {

server/store/group_message_runtime_test.go

@@ -114,8 +114,8 @@ func (r *testGroupMessageRuntime) RefreshUserPresence(types.TenantID, types.Uid,
 	return nil
 }
 
-func (r *testGroupMessageRuntime) MarkUserOffline(types.TenantID, types.Uid, string, string) error {
-	return nil
+func (r *testGroupMessageRuntime) MarkUserOffline(types.TenantID, types.Uid, string, string) (int, error) {
+	return 0, nil
 }
 
 func (r *testGroupMessageRuntime) GetUserPresence(types.TenantID, types.Uid) (*UserPresence, error) {