MM-62751: [Shared Channels] Allow remote users to be discoverable in the create DM/GM modal (#30918)

server/platform/services/remotecluster/service.go

@@ -289,3 +289,19 @@ func (rcs *Service) pause() {
 
 	rcs.server.Log().Debug("Remote Cluster Service inactive")
 }
+
+// SetActive forces the service to be active or inactive
+func (rcs *Service) SetActive(active bool) {
+	rcs.mux.Lock()
+	defer rcs.mux.Unlock()
+
+	if rcs.active == active {
+		return
+	}
+
+	if active {
+		rcs.resume()
+	} else {
+		rcs.pause()
+	}
+}

server/platform/services/sharedchannel/service.go

@@ -24,6 +24,7 @@ const (
 	TopicSync                    = "sharedchannel_sync"
 	TopicChannelInvite           = "sharedchannel_invite"
 	TopicUploadCreate            = "sharedchannel_upload"
+	TopicGlobalUserSync          = "sharedchannel_global_user_sync"
 	MaxRetries                   = 3
 	MaxUsersPerSync              = 25
 	NotifyRemoteOfflineThreshold = time.Second * 10
@@ -98,6 +99,7 @@ type Service struct {
 	syncTopicListenerId       string
 	inviteTopicListenerId     string
 	uploadTopicListenerId     string
+	globalSyncTopicListenerId string
 	siteURL                   *url.URL
 }
 
@@ -130,6 +132,7 @@ func (scs *Service) Start() error {
 	scs.syncTopicListenerId = rcs.AddTopicListener(TopicSync, scs.onReceiveSyncMessage)
 	scs.inviteTopicListenerId = rcs.AddTopicListener(TopicChannelInvite, scs.onReceiveChannelInvite)
 	scs.uploadTopicListenerId = rcs.AddTopicListener(TopicUploadCreate, scs.onReceiveUploadCreate)
+	scs.globalSyncTopicListenerId = rcs.AddTopicListener(TopicGlobalUserSync, scs.onReceiveSyncMessage)
 	scs.connectionStateListenerId = rcs.AddConnectionStateListener(scs.onConnectionStateChange)
 	scs.mux.Unlock()
 
@@ -248,6 +251,9 @@ func (scs *Service) onConnectionStateChange(rc *model.RemoteCluster, online bool
 		// when a previously offline remote comes back online force a sync.
 		scs.SendPendingInvitesForRemote(rc)
 		scs.ForceSyncForRemote(rc)
+
+		// Schedule global user sync if feature is enabled
+		scs.scheduleGlobalUserSync(rc)
 	}
 
 	scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Remote cluster connection status changed",
@@ -278,3 +284,47 @@ func (scs *Service) notifyClientsForSharedChannelUpdate(channel *model.Channel)
 	messageWs.Add("channel_id", channel.Id)
 	scs.app.Publish(messageWs)
 }
+
+// isGlobalUserSyncEnabled checks if the global user sync feature is enabled
+func (scs *Service) isGlobalUserSyncEnabled() bool {
+	cfg := scs.server.Config()
+
+	return cfg.FeatureFlags.EnableSyncAllUsersForRemoteCluster ||
+		(cfg.ConnectedWorkspacesSettings.SyncUsersOnConnectionOpen != nil && *cfg.ConnectedWorkspacesSettings.SyncUsersOnConnectionOpen)
+}
+
+// scheduleGlobalUserSync schedules a task to sync all users with a remote cluster
+func (scs *Service) scheduleGlobalUserSync(rc *model.RemoteCluster) {
+	if !scs.isGlobalUserSyncEnabled() {
+		return
+	}
+
+	// Schedule the sync task
+	go func() {
+		// Create a special sync task with empty channelID
+		// This empty channelID is a deliberate marker for a global user sync task
+		task := newSyncTask("", "", rc.RemoteId, nil, nil)
+		task.schedule = time.Now().Add(NotifyMinimumDelay)
+		scs.addTask(task)
+
+		scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Scheduled global user sync task for remote",
+			mlog.String("remote", rc.DisplayName),
+			mlog.String("remoteId", rc.RemoteId),
+		)
+	}()
+}
+
+// OnReceiveSyncMessageForTesting exposes onReceiveSyncMessage for testing
+func (scs *Service) OnReceiveSyncMessageForTesting(msg model.RemoteClusterMsg, rc *model.RemoteCluster, response *remotecluster.Response) error {
+	return scs.onReceiveSyncMessage(msg, rc, response)
+}
+
+// GetUserSyncBatchSizeForTesting returns the configured batch size for user syncing (exported for testing)
+func (scs *Service) GetUserSyncBatchSizeForTesting() int {
+	return scs.getGlobalUserSyncBatchSize()
+}
+
+// HandleSyncAllUsersForTesting exposes syncAllUsers for testing
+func (scs *Service) HandleSyncAllUsersForTesting(rc *model.RemoteCluster) error {
+	return scs.syncAllUsers(rc)
+}

server/platform/services/sharedchannel/sync_recv.go

@@ -24,8 +24,8 @@ var (
 )
 
 func (scs *Service) onReceiveSyncMessage(msg model.RemoteClusterMsg, rc *model.RemoteCluster, response *remotecluster.Response) error {
-	if msg.Topic != TopicSync {
-		return fmt.Errorf("wrong topic, expected `%s`, got `%s`", TopicSync, msg.Topic)
+	if msg.Topic != TopicSync && msg.Topic != TopicGlobalUserSync {
+		return fmt.Errorf("wrong topic, expected `%s` or `%s`, got `%s`", TopicSync, TopicGlobalUserSync, msg.Topic)
 	}
 
 	if len(msg.Payload) == 0 {
@@ -47,6 +47,36 @@ func (scs *Service) onReceiveSyncMessage(msg model.RemoteClusterMsg, rc *model.R
 	return scs.processSyncMessage(request.EmptyContext(scs.server.Log()), &sm, rc, response)
 }
 
+func (scs *Service) processGlobalUserSync(c request.CTX, syncMsg *model.SyncMsg, rc *model.RemoteCluster, response *remotecluster.Response) error {
+	syncResp := model.SyncResponse{
+		UserErrors: make([]string, 0),
+		UsersSyncd: make([]string, 0),
+	}
+
+	scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Processing global user sync",
+		mlog.String("remote", rc.Name),
+		mlog.Int("user_count", len(syncMsg.Users)),
+	)
+
+	// Process all users in the sync message
+	for _, user := range syncMsg.Users {
+		if userSaved, err := scs.upsertSyncUser(c, user, nil, rc); err != nil {
+			syncResp.UserErrors = append(syncResp.UserErrors, user.Id)
+		} else {
+			syncResp.UsersSyncd = append(syncResp.UsersSyncd, userSaved.Id)
+			if syncResp.UsersLastUpdateAt < user.UpdateAt {
+				syncResp.UsersLastUpdateAt = user.UpdateAt
+			}
+			scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Global user upserted via sync",
+				mlog.String("remote", rc.Name),
+				mlog.String("user_id", user.Id),
+			)
+		}
+	}
+
+	return response.SetPayload(syncResp)
+}
+
 func (scs *Service) processSyncMessage(c request.CTX, syncMsg *model.SyncMsg, rc *model.RemoteCluster, response *remotecluster.Response) error {
 	var targetChannel *model.Channel
 	var team *model.Team
@@ -68,6 +98,25 @@ func (scs *Service) processSyncMessage(c request.CTX, syncMsg *model.SyncMsg, rc
 		mlog.Int("status_count", len(syncMsg.Statuses)),
 	)
 
+	// Check if this is a global user sync message (no channel ID and only users)
+	if syncMsg.ChannelId == "" {
+		if len(syncMsg.Posts) != 0 ||
+			len(syncMsg.Reactions) != 0 ||
+			len(syncMsg.Statuses) != 0 {
+			return fmt.Errorf("global user sync message should not contain posts, reactions or statuses")
+		}
+
+		if len(syncMsg.Users) == 0 {
+			return nil
+		}
+		// Check if feature flag is enabled
+		if !scs.isGlobalUserSyncEnabled() {
+			return nil
+		}
+		return scs.processGlobalUserSync(c, syncMsg, rc, response)
+	}
+
+	// For regular sync messages, we need a specific channel
 	if targetChannel, err = scs.server.GetStore().Channel().Get(syncMsg.ChannelId, true); err != nil {
 		// if the channel doesn't exist then none of these sync items are going to work.
 		return fmt.Errorf("channel not found processing sync message: %w", err)
@@ -239,7 +288,7 @@ func (scs *Service) upsertSyncUser(c request.CTX, user *model.User, channel *mod
 	// Instead of undoing what succeeded on any failure we simply do all steps each
 	// time. AddUserToChannel & AddUserToTeamByTeamId do not error if user was already
 	// added and exit quickly.  Not needed for DMs where teamId is empty.
-	if channel.TeamId != "" {
+	if channel != nil && channel.TeamId != "" {
 		// add user to team
 		if err := scs.app.AddUserToTeamByTeamId(request.EmptyContext(scs.server.Log()), channel.TeamId, userSaved); err != nil {
 			return nil, fmt.Errorf("error adding sync user to Team: %w", err)

server/platform/services/sharedchannel/sync_send.go

@@ -571,14 +571,14 @@ func (scs *Service) shouldUserSync(user *model.User, channelID string, rc *model
 		if _, err = scs.server.GetStore().SharedChannel().SaveUser(scu); err != nil {
 			scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error adding user to shared channel users",
 				mlog.String("user_id", user.Id),
-				mlog.String("channel_id", user.Id),
+				mlog.String("channel_id", channelID),
 				mlog.String("remote_id", rc.RemoteId),
 				mlog.Err(err),
 			)
 		} else {
 			scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Added user to shared channel users",
 				mlog.String("user_id", user.Id),
-				mlog.String("channel_id", user.Id),
+				mlog.String("channel_id", channelID),
 				mlog.String("remote_id", rc.RemoteId),
 			)
 		}

server/platform/services/sharedchannel/sync_send_remote.go

@@ -39,8 +39,9 @@ type syncData struct {
 	statuses      []*model.Status
 	attachments   []attachment
 
-	resultRepeat     bool
-	resultNextCursor model.GetPostsSinceForSyncCursor
+	resultRepeat                bool
+	resultNextCursor            model.GetPostsSinceForSyncCursor
+	GlobalUserSyncLastTimestamp int64
 }
 
 func newSyncData(task syncTask, rc *model.RemoteCluster, scr *model.SharedChannelRemote) *syncData {
@@ -83,6 +84,12 @@ func (sd *syncData) setDataFromMsg(msg *model.SyncMsg) {
 // channels are very active.
 // Returning an error forces a retry on the task.
 func (scs *Service) syncForRemote(task syncTask, rc *model.RemoteCluster) error {
+	// Empty channelID indicates a global user sync task
+	// Normal syncTasks always include a valid channelID
+	if task.channelID == "" {
+		return scs.syncAllUsers(rc)
+	}
+
 	rcs := scs.server.GetRemoteClusterService()
 	if rcs == nil {
 		return fmt.Errorf("cannot update remote cluster %s for channel id %s; Remote Cluster Service not enabled", rc.Name, task.channelID)
@@ -241,6 +248,7 @@ func (scs *Service) fetchUsersForSync(sd *syncData) error {
 		return err
 	}
 
+	// Don't sync users back to the remote cluster they originated from
 	for _, u := range users {
 		if u.GetRemoteID() != sd.rc.RemoteId {
 			sd.users[u.Id] = u
@@ -495,7 +503,7 @@ func (scs *Service) filterPostsForSync(sd *syncData) {
 			continue
 		}
 
-		// don't sync a post back to the remote it came from.
+		// don't sync a post back to the remote cluster it came from.
 		if p.GetRemoteID() == sd.rc.RemoteId {
 			continue
 		}
@@ -578,6 +586,11 @@ func (scs *Service) sendUserSyncData(sd *syncData) error {
 	msg.Users = sd.users
 
 	err := scs.sendSyncMsgToRemote(msg, sd.rc, func(syncResp model.SyncResponse, errResp error) {
+		// Only update cursor on successful sync
+		if errResp == nil && sd.GlobalUserSyncLastTimestamp > 0 {
+			scs.updateGlobalSyncCursor(sd.rc, sd.GlobalUserSyncLastTimestamp)
+		}
+
 		for _, userID := range syncResp.UsersSyncd {
 			if err := scs.server.GetStore().SharedChannel().UpdateUserLastSyncAt(userID, sd.task.channelID, sd.rc.RemoteId); err != nil {
 				scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Cannot update shared channel user LastSyncAt",
@@ -691,6 +704,204 @@ func (scs *Service) sendProfileImageSyncData(sd *syncData) {
 	}
 }
 
+// shouldUserSyncGlobal determines if a user needs to be synchronized globally.
+// Compares user's update timestamp with the remote cluster's LastGlobalUserSyncAt.
+func (scs *Service) shouldUserSyncGlobal(user *model.User, rc *model.RemoteCluster) (bool, error) {
+	// Don't sync users back to the remote cluster they originated from
+	if user.IsRemote() && user.GetRemoteID() == rc.RemoteId {
+		return false, nil
+	}
+
+	// Calculate latest update time for this user (profile or picture)
+	latestUserUpdateTime := user.UpdateAt
+	if user.LastPictureUpdate > latestUserUpdateTime {
+		latestUserUpdateTime = user.LastPictureUpdate
+	}
+
+	// For initial sync (LastGlobalUserSyncAt=0), sync all users
+	// For incremental sync, only sync users updated after the last sync
+	if rc.LastGlobalUserSyncAt == 0 {
+		return true, nil
+	}
+	return latestUserUpdateTime > rc.LastGlobalUserSyncAt, nil
+}
+
+// syncAllUsers synchronizes all local users to a remote cluster.
+// This is called when a connection with a remote cluster is established or when handling a global user sync task.
+// Uses cursor-based approach with LastGlobalUserSyncAt to resume after interruptions.
+func (scs *Service) syncAllUsers(rc *model.RemoteCluster) error {
+	// Check if feature is enabled
+	if !scs.server.Config().FeatureFlags.EnableSyncAllUsersForRemoteCluster {
+		return nil
+	}
+
+	if !rc.IsOnline() {
+		return fmt.Errorf("remote cluster %s is not online", rc.RemoteId)
+	}
+
+	// Start metrics tracking
+	metrics := scs.server.GetMetrics()
+	start := time.Now()
+	defer func() {
+		if metrics != nil {
+			metrics.IncrementSharedChannelsSyncCounter(rc.RemoteId)
+			metrics.ObserveSharedChannelsSyncCollectionDuration(rc.RemoteId, time.Since(start).Seconds())
+		}
+	}()
+
+	batchSize := scs.getGlobalUserSyncBatchSize()
+
+	// Create sync data with collected users
+	sd := &syncData{
+		task:  syncTask{remoteID: rc.RemoteId},
+		rc:    rc,
+		scr:   &model.SharedChannelRemote{RemoteId: rc.RemoteId},
+		users: make(map[string]*model.User),
+	}
+
+	// Collect users to sync
+	users, latestTimestamp, _, hasMore, err := scs.collectUsersForGlobalSync(rc, batchSize)
+	if err != nil {
+		return err
+	}
+
+	// Exit early if no users to sync
+	if len(users) == 0 {
+		scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "No users to sync for remote cluster",
+			mlog.String("remote_id", rc.RemoteId))
+		return nil
+	}
+
+	// Add users to sync data
+	sd.users = users
+	sd.GlobalUserSyncLastTimestamp = latestTimestamp
+
+	// Send the collected users to remote
+	if err := scs.sendUserSyncData(sd); err != nil {
+		scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error sending user batch during sync",
+			mlog.String("remote_id", rc.RemoteId),
+			mlog.Err(err),
+		)
+		return fmt.Errorf("error sending user batch during sync: %w", err)
+	}
+
+	// Schedule next batch if needed
+	if hasMore {
+		scs.scheduleNextUserSyncBatch(rc, latestTimestamp, batchSize, len(users))
+	}
+
+	return nil
+}
+
+// getGlobalUserSyncBatchSize returns the configured batch size for user syncing
+func (scs *Service) getGlobalUserSyncBatchSize() int {
+	batchSize := MaxUsersPerSync
+	if scs.server.Config().ConnectedWorkspacesSettings.GlobalUserSyncBatchSize != nil {
+		configValue := *scs.server.Config().ConnectedWorkspacesSettings.GlobalUserSyncBatchSize
+		if configValue > 0 && configValue <= 200 {
+			batchSize = configValue
+		}
+	}
+	return batchSize
+}
+
+// collectUsersForGlobalSync fetches users that need to be synced to the remote
+func (scs *Service) collectUsersForGlobalSync(rc *model.RemoteCluster, batchSize int) (map[string]*model.User, int64, int, bool, error) {
+	options := &model.UserGetOptions{
+		Page:    0,
+		PerPage: 100, // Database fetch batch size
+		Active:  true,
+		Sort:    "update_at_asc", // Order by UpdateAt ASC to ensure cursor consistency
+	}
+
+	// Only use UpdatedAfter for incremental syncs, not the initial sync
+	// This ensures users with UpdateAt=0 are included in the first sync
+	if rc.LastGlobalUserSyncAt > 0 {
+		options.UpdatedAfter = rc.LastGlobalUserSyncAt
+	}
+
+	users := make(map[string]*model.User)
+	latestTimestamp := rc.LastGlobalUserSyncAt
+	totalCount := 0
+
+	// Page through database results
+	for {
+		batch, err := scs.server.GetStore().User().GetAllProfiles(options)
+		if err != nil {
+			scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error fetching users for global sync",
+				mlog.String("remote_id", rc.RemoteId),
+				mlog.Err(err),
+			)
+			return nil, 0, 0, false, err
+		}
+
+		if len(batch) == 0 {
+			break // No more users to process
+		}
+
+		totalCount += len(batch)
+
+		// Process each user in this database page
+		for _, user := range batch {
+			// Stop if we've reached batch limit
+			if len(users) >= batchSize {
+				return users, latestTimestamp, totalCount, true, nil
+			}
+
+			// Skip users from remotes
+			if user.IsRemote() {
+				continue
+			}
+
+			// Check if user needs syncing
+			needsSync, _ := scs.shouldUserSyncGlobal(user, rc)
+			if !needsSync {
+				continue
+			}
+
+			// Add user and update cursor timestamp
+			users[user.Id] = user
+
+			userUpdateTime := max(user.UpdateAt, user.LastPictureUpdate)
+			if userUpdateTime > latestTimestamp {
+				latestTimestamp = userUpdateTime
+			}
+		}
+
+		// Check if we've reached the end of results
+		if len(batch) < options.PerPage {
+			break
+		}
+
+		// Move to next page
+		options.Page++
+	}
+
+	return users, latestTimestamp, totalCount, false, nil
+}
+
+// updateGlobalSyncCursor updates the LastGlobalUserSyncAt value for the remote cluster
+func (scs *Service) updateGlobalSyncCursor(rc *model.RemoteCluster, newTimestamp int64) {
+	if err := scs.server.GetStore().RemoteCluster().UpdateLastGlobalUserSyncAt(rc.RemoteId, newTimestamp); err == nil {
+		rc.LastGlobalUserSyncAt = newTimestamp
+	} else {
+		scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Failed to update global user sync cursor",
+			mlog.String("remote_id", rc.RemoteId),
+			mlog.Err(err),
+		)
+	}
+}
+
+// scheduleNextUserSyncBatch creates a new task for the next batch of user sync
+func (scs *Service) scheduleNextUserSyncBatch(rc *model.RemoteCluster, timestamp int64, batchSize, processedCount int) {
+	// Use timestamp as userID to make each batch task unique
+	// This prevents task ID collisions between different batches for the same remote
+	timestampStr := fmt.Sprintf("%d", timestamp)
+	task := newSyncTask("", timestampStr, rc.RemoteId, nil, nil)
+	task.schedule = time.Now().Add(NotifyMinimumDelay)
+	scs.addTask(task)
+}
+
 // sendSyncMsgToRemote synchronously sends the sync message to the remote cluster (or plugin).
 func (scs *Service) sendSyncMsgToRemote(msg *model.SyncMsg, rc *model.RemoteCluster, f sendSyncMsgResultFunc) error {
 	rcs := scs.server.GetRemoteClusterService()
@@ -706,7 +917,15 @@ func (scs *Service) sendSyncMsgToRemote(msg *model.SyncMsg, rc *model.RemoteClus
 	if err != nil {
 		return err
 	}
-	rcMsg := model.NewRemoteClusterMsg(TopicSync, b)
+
+	// Use appropriate topic based on message type
+	topic := TopicSync
+	if msg.ChannelId == "" && len(msg.Users) > 0 &&
+		len(msg.Posts) == 0 && len(msg.Reactions) == 0 &&
+		len(msg.Statuses) == 0 {
+		topic = TopicGlobalUserSync
+	}
+	rcMsg := model.NewRemoteClusterMsg(topic, b)
 
 	ctx, cancel := context.WithTimeout(context.Background(), remotecluster.SendTimeout)
 	defer cancel()