Adding the new search engine abstraction (#13304)

* WIP * Adding bleve to go modules * WIP * Adding missing files from searchengine implementation * WIP * WIP * WIP * WIP * WIP * WIP * User and channel indexing and searches implemented * Make bleve tests run with in-memory indexes * Implement post index and deletion tests * Initial commits for the search layer * Removing unnecesary indexing * WIP * WIP * More fixes for tests * Adding the search layer * Finishing the migration of searchers to the layer * Removing unnecesary code * Allowing multiple engines active at the same time * WIP * Add simple post search * Print information when using bleve * Adding some debugging to understand better how the searches are working * Making more dynamic config of search engines * Add post search basics * Adding the Purge API endpoint * Fixing bleve config updates * Adding missed file * Regenerating search engine mocks * Adding missed v5 to modules imports * fixing i18n * Fixing some test around search engine * Removing all bleve traces * Cleaning up the vendors directory and go.mod/go.sum files * Regenerating timer layer * Adding properly the license * Fixing govet shadow error * Fixing some tests * Fixing TestSearchPostsFromUser * Fixing another test * Fixing more tests * Fixing more tests * Removing SearchEngine redundant text from searchengine module code * Fixing some reindexing problems in members updates * Fixing tests * Addressing PR comments * Reverting go.mod and go.sum * Addressing PR comments * Fixing tests compilation * Fixing govet * Adding search engine stop method * Being more explicit on where we use includeDeleted * Adding GetSqlSupplier test helper method * Mocking elasticsearch start function * Fixing tests Co-authored-by: Miguel de la Cruz <miguel@mcrx.me> Co-authored-by: mattermod <mattermod@users.noreply.github.com>
2020-03-13 15:33:18 +01:00
--- a/store/searchlayer/channel_layer.go
+++ b/store/searchlayer/channel_layer.go
@@ -0,0 +1,207 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package searchlayer
+
+import (
+	"github.com/mattermost/mattermost-server/v5/mlog"
+	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/services/searchengine"
+	"github.com/mattermost/mattermost-server/v5/store"
+)
+
+type SearchChannelStore struct {
+	store.ChannelStore
+	rootStore *SearchStore
+}
+
+func (c *SearchChannelStore) deleteChannelIndex(channel *model.Channel) {
+	if channel.Type == model.CHANNEL_OPEN {
+		for _, engine := range c.rootStore.searchEngine.GetActiveEngines() {
+			if engine.IsIndexingEnabled() {
+				go (func(engineCopy searchengine.SearchEngineInterface) {
+					if err := engineCopy.DeleteChannel(channel); err != nil {
+						mlog.Error("Encountered error deleting channel", mlog.String("channel_id", channel.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+					}
+					mlog.Debug("Removed channel from index in search engine", mlog.String("search_engine", engineCopy.GetName()), mlog.String("channel_id", channel.Id))
+				})(engine)
+			}
+		}
+	}
+}
+
+func (c *SearchChannelStore) indexChannel(channel *model.Channel) {
+	if channel.Type == model.CHANNEL_OPEN {
+		for _, engine := range c.rootStore.searchEngine.GetActiveEngines() {
+			if engine.IsIndexingEnabled() {
+				go (func(engineCopy searchengine.SearchEngineInterface) {
+					if err := engineCopy.IndexChannel(channel); err != nil {
+						mlog.Error("Encountered error indexing channel", mlog.String("channel_id", channel.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+					}
+					mlog.Debug("Indexed channel in search engine", mlog.String("search_engine", engineCopy.GetName()), mlog.String("channel_id", channel.Id))
+				})(engine)
+			}
+		}
+	}
+}
+
+func (c *SearchChannelStore) Save(channel *model.Channel, maxChannels int64) (*model.Channel, *model.AppError) {
+	newChannel, err := c.ChannelStore.Save(channel, maxChannels)
+	if err == nil {
+		c.indexChannel(newChannel)
+	}
+	return newChannel, err
+}
+
+func (c *SearchChannelStore) Update(channel *model.Channel) (*model.Channel, *model.AppError) {
+	updatedChannel, err := c.ChannelStore.Update(channel)
+	if err == nil {
+		c.indexChannel(updatedChannel)
+	}
+	return updatedChannel, err
+}
+
+func (c *SearchChannelStore) UpdateMember(cm *model.ChannelMember) (*model.ChannelMember, *model.AppError) {
+	member, err := c.ChannelStore.UpdateMember(cm)
+	if err == nil {
+		c.rootStore.indexUserFromID(cm.UserId)
+		channel, channelErr := c.ChannelStore.Get(member.ChannelId, true)
+		if channelErr != nil {
+			mlog.Error("Encountered error indexing user in channel", mlog.String("channel_id", member.ChannelId), mlog.Err(err))
+		} else {
+			c.rootStore.indexUserFromID(channel.CreatorId)
+		}
+	}
+	return member, err
+}
+
+func (c *SearchChannelStore) SaveMember(cm *model.ChannelMember) (*model.ChannelMember, *model.AppError) {
+	member, err := c.ChannelStore.SaveMember(cm)
+	if err == nil {
+		c.rootStore.indexUserFromID(cm.UserId)
+		channel, channelErr := c.ChannelStore.Get(member.ChannelId, true)
+		if channelErr != nil {
+			mlog.Error("Encountered error indexing user in channel", mlog.String("channel_id", member.ChannelId), mlog.Err(err))
+		} else {
+			c.rootStore.indexUserFromID(channel.CreatorId)
+		}
+	}
+	return member, err
+}
+
+func (c *SearchChannelStore) RemoveMember(channelId, userIdToRemove string) *model.AppError {
+	err := c.ChannelStore.RemoveMember(channelId, userIdToRemove)
+	if err == nil {
+		c.rootStore.indexUserFromID(userIdToRemove)
+	}
+	return err
+}
+
+func (c *SearchChannelStore) CreateDirectChannel(user *model.User, otherUser *model.User) (*model.Channel, *model.AppError) {
+	channel, err := c.ChannelStore.CreateDirectChannel(user, otherUser)
+	if err == nil {
+		c.rootStore.indexUserFromID(user.Id)
+		c.rootStore.indexUserFromID(otherUser.Id)
+	}
+	return channel, err
+}
+
+func (c *SearchChannelStore) AutocompleteInTeam(teamId string, term string, includeDeleted bool) (*model.ChannelList, *model.AppError) {
+	var channelList *model.ChannelList
+	var err *model.AppError
+
+	allFailed := true
+	for _, engine := range c.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsAutocompletionEnabled() {
+			channelList, err = c.searchAutocompleteChannels(engine, teamId, term, includeDeleted)
+			if err != nil {
+				mlog.Error("Encountered error on AutocompleteChannels through SearchEngine. Falling back to default autocompletion.", mlog.String("search_engine", engine.GetName()), mlog.Err(err))
+				continue
+			}
+			allFailed = false
+			mlog.Debug("Using the first available search engine", mlog.String("search_engine", engine.GetName()))
+			break
+		}
+	}
+
+	if allFailed {
+		mlog.Debug("Using database search because no other search engine is available")
+		channelList, err = c.ChannelStore.AutocompleteInTeam(teamId, term, includeDeleted)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return channelList, err
+}
+
+func (c *SearchChannelStore) searchAutocompleteChannels(engine searchengine.SearchEngineInterface, teamId, term string, includeDeleted bool) (*model.ChannelList, *model.AppError) {
+	channelIds, err := engine.SearchChannels(teamId, term)
+	if err != nil {
+		return nil, err
+	}
+
+	channelList := model.ChannelList{}
+	if len(channelIds) > 0 {
+		channels, err := c.ChannelStore.GetChannelsByIds(channelIds, includeDeleted)
+		if err != nil {
+			return nil, err
+		}
+		for _, ch := range channels {
+			channelList = append(channelList, ch)
+		}
+	}
+
+	return &channelList, nil
+}
+
+func (c *SearchChannelStore) PermanentDeleteMembersByUser(userId string) *model.AppError {
+	err := c.ChannelStore.PermanentDeleteMembersByUser(userId)
+	if err == nil {
+		c.rootStore.indexUserFromID(userId)
+	}
+	return err
+}
+
+func (c *SearchChannelStore) RemoveAllDeactivatedMembers(channelId string) *model.AppError {
+	profiles, errProfiles := c.rootStore.User().GetAllProfilesInChannel(channelId, true)
+	if errProfiles != nil {
+		mlog.Error("Encountered error indexing users for channel", mlog.String("channel_id", channelId), mlog.Err(errProfiles))
+	}
+
+	err := c.ChannelStore.RemoveAllDeactivatedMembers(channelId)
+	if err == nil && errProfiles == nil {
+		for _, user := range profiles {
+			if user.DeleteAt != 0 {
+				c.rootStore.indexUser(user)
+			}
+		}
+	}
+	return err
+}
+
+func (c *SearchChannelStore) PermanentDeleteMembersByChannel(channelId string) *model.AppError {
+	profiles, errProfiles := c.rootStore.User().GetAllProfilesInChannel(channelId, true)
+	if errProfiles != nil {
+		mlog.Error("Encountered error indexing users for channel", mlog.String("channel_id", channelId), mlog.Err(errProfiles))
+	}
+
+	err := c.ChannelStore.PermanentDeleteMembersByChannel(channelId)
+	if err == nil && errProfiles == nil {
+		for _, user := range profiles {
+			c.rootStore.indexUser(user)
+		}
+	}
+	return err
+}
+
+func (c *SearchChannelStore) PermanentDelete(channelId string) *model.AppError {
+	channel, channelErr := c.ChannelStore.Get(channelId, true)
+	if channelErr != nil {
+		mlog.Error("Encountered error deleting channel", mlog.String("channel_id", channelId), mlog.Err(channelErr))
+	}
+	err := c.ChannelStore.PermanentDelete(channelId)
+	if err == nil && channelErr == nil {
+		c.deleteChannelIndex(channel)
+	}
+	return err
+}
--- a/store/searchlayer/layer.go
+++ b/store/searchlayer/layer.go
@@ -0,0 +1,93 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package searchlayer
+
+import (
+	"github.com/mattermost/mattermost-server/v5/mlog"
+	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/services/searchengine"
+	"github.com/mattermost/mattermost-server/v5/store"
+)
+
+type SearchStore struct {
+	store.Store
+	searchEngine *searchengine.Broker
+	user         *SearchUserStore
+	team         *SearchTeamStore
+	channel      *SearchChannelStore
+	post         *SearchPostStore
+}
+
+func NewSearchLayer(baseStore store.Store, searchEngine *searchengine.Broker) SearchStore {
+	searchStore := SearchStore{
+		Store:        baseStore,
+		searchEngine: searchEngine,
+	}
+	searchStore.channel = &SearchChannelStore{ChannelStore: baseStore.Channel(), rootStore: &searchStore}
+	searchStore.post = &SearchPostStore{PostStore: baseStore.Post(), rootStore: &searchStore}
+	searchStore.team = &SearchTeamStore{TeamStore: baseStore.Team(), rootStore: &searchStore}
+	searchStore.user = &SearchUserStore{UserStore: baseStore.User(), rootStore: &searchStore}
+
+	return searchStore
+}
+
+func (s SearchStore) Channel() store.ChannelStore {
+	return s.channel
+}
+
+func (s SearchStore) Post() store.PostStore {
+	return s.post
+}
+
+func (s SearchStore) Team() store.TeamStore {
+	return s.team
+}
+
+func (s SearchStore) User() store.UserStore {
+	return s.user
+}
+
+func (s SearchStore) indexUserFromID(userId string) {
+	user, err := s.User().Get(userId)
+	if err != nil {
+		return
+	}
+	s.indexUser(user)
+}
+
+func (s SearchStore) indexUser(user *model.User) {
+	for _, engine := range s.searchEngine.GetActiveEngines() {
+		if engine.IsIndexingEnabled() {
+			go (func(engineCopy searchengine.SearchEngineInterface) {
+				userTeams, err := s.Team().GetTeamsByUserId(user.Id)
+				if err != nil {
+					mlog.Error("Encountered error indexing user", mlog.String("user_id", user.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+					return
+				}
+
+				userTeamsIds := []string{}
+				for _, team := range userTeams {
+					userTeamsIds = append(userTeamsIds, team.Id)
+				}
+
+				userChannelMembers, err := s.Channel().GetAllChannelMembersForUser(user.Id, false, true)
+				if err != nil {
+					mlog.Error("Encountered error indexing user", mlog.String("user_id", user.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+					return
+				}
+
+				userChannelsIds := []string{}
+				for channelId := range userChannelMembers {
+					userChannelsIds = append(userChannelsIds, channelId)
+				}
+
+				if err := engineCopy.IndexUser(user, userTeamsIds, userChannelsIds); err != nil {
+					mlog.Error("Encountered error indexing user", mlog.String("user_id", user.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+					return
+				}
+				mlog.Debug("Indexed user in search engine", mlog.String("search_engine", engineCopy.GetName()), mlog.String("user_id", user.Id))
+			})(engine)
+		}
+	}
+}
--- a/store/searchlayer/post_layer.go
+++ b/store/searchlayer/post_layer.go
@@ -0,0 +1,126 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package searchlayer
+
+import (
+	"github.com/mattermost/mattermost-server/v5/mlog"
+	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/services/searchengine"
+	"github.com/mattermost/mattermost-server/v5/store"
+)
+
+type SearchPostStore struct {
+	store.PostStore
+	rootStore *SearchStore
+}
+
+func (s SearchPostStore) indexPost(post *model.Post) {
+	for _, engine := range s.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsIndexingEnabled() {
+			go (func(engineCopy searchengine.SearchEngineInterface) {
+				channel, chanErr := s.rootStore.Channel().GetForPost(post.Id)
+				if chanErr != nil {
+					mlog.Error("Couldn't get channel for post for SearchEngine indexing.", mlog.String("channel_id", post.ChannelId), mlog.String("search_engine", engineCopy.GetName()), mlog.String("post_id", post.Id))
+					return
+				}
+				if err := engineCopy.IndexPost(post, channel.TeamId); err != nil {
+					mlog.Error("Encountered error indexing post", mlog.String("post_id", post.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+				}
+				mlog.Debug("Indexed post in search engine", mlog.String("search_engine", engineCopy.GetName()), mlog.String("post_id", post.Id))
+			})(engine)
+		}
+	}
+}
+
+func (s SearchPostStore) deletePostIndex(post *model.Post) {
+	for _, engine := range s.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsIndexingEnabled() {
+			go (func(engineCopy searchengine.SearchEngineInterface) {
+				if err := engineCopy.DeletePost(post); err != nil {
+					mlog.Error("Encountered error deleting post", mlog.String("post_id", post.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+				}
+				mlog.Debug("Removed post from the index in search engine", mlog.String("search_engine", engineCopy.GetName()), mlog.String("post_id", post.Id))
+			})(engine)
+		}
+	}
+}
+
+func (s SearchPostStore) Update(newPost, oldPost *model.Post) (*model.Post, *model.AppError) {
+	post, err := s.PostStore.Update(newPost, oldPost)
+
+	if err == nil {
+		s.indexPost(post)
+	}
+	return post, err
+}
+
+func (s SearchPostStore) Save(post *model.Post) (*model.Post, *model.AppError) {
+	npost, err := s.PostStore.Save(post)
+
+	if err == nil {
+		s.indexPost(npost)
+	}
+	return npost, err
+}
+
+func (s SearchPostStore) Delete(postId string, date int64, deletedByID string) *model.AppError {
+	err := s.PostStore.Delete(postId, date, deletedByID)
+
+	if err == nil {
+		postList, err2 := s.PostStore.Get(postId, true)
+		if postList != nil && len(postList.Order) > 0 {
+			if err2 != nil {
+				s.deletePostIndex(postList.Posts[postList.Order[0]])
+			}
+		}
+	}
+	return err
+}
+
+func (s SearchPostStore) searchPostsInTeamForUserByEngine(engine searchengine.SearchEngineInterface, paramsList []*model.SearchParams, userId, teamId string, isOrSearch, includeDeletedChannels bool, page, perPage int) (*model.PostSearchResults, *model.AppError) {
+	// We only allow the user to search in channels they are a member of.
+	userChannels, err := s.rootStore.Channel().GetChannels(teamId, userId, includeDeletedChannels)
+	if err != nil {
+		mlog.Error("error getting channel for user", mlog.Err(err))
+		return nil, err
+	}
+
+	postIds, matches, err := engine.SearchPosts(userChannels, paramsList, page, perPage)
+	if err != nil {
+		return nil, err
+	}
+
+	// Get the posts
+	postList := model.NewPostList()
+	if len(postIds) > 0 {
+		posts, err := s.PostStore.GetPostsByIds(postIds)
+		if err != nil {
+			return nil, err
+		}
+		for _, p := range posts {
+			if p.DeleteAt == 0 {
+				postList.AddPost(p)
+				postList.AddOrder(p.Id)
+			}
+		}
+	}
+
+	return model.MakePostSearchResults(postList, matches), nil
+}
+
+func (s SearchPostStore) SearchPostsInTeamForUser(paramsList []*model.SearchParams, userId, teamId string, isOrSearch, includeDeletedChannels bool, page, perPage int) (*model.PostSearchResults, *model.AppError) {
+	for _, engine := range s.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsSearchEnabled() {
+			results, err := s.searchPostsInTeamForUserByEngine(engine, paramsList, userId, teamId, isOrSearch, includeDeletedChannels, page, perPage)
+			if err != nil {
+				mlog.Error("Encountered error on SearchPostsInTeamForUser.", mlog.String("search_engine", engine.GetName()), mlog.Err(err))
+				continue
+			}
+			mlog.Debug("Using the first available search engine", mlog.String("search_engine", engine.GetName()))
+			return results, err
+		}
+	}
+	mlog.Debug("Using database search because no other search engine is available")
+	return s.PostStore.SearchPostsInTeamForUser(paramsList, userId, teamId, isOrSearch, includeDeletedChannels, page, perPage)
+}
--- a/store/searchlayer/team_layer.go
+++ b/store/searchlayer/team_layer.go
@@ -0,0 +1,46 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package searchlayer
+
+import (
+	model "github.com/mattermost/mattermost-server/v5/model"
+	store "github.com/mattermost/mattermost-server/v5/store"
+)
+
+type SearchTeamStore struct {
+	store.TeamStore
+	rootStore *SearchStore
+}
+
+func (s SearchTeamStore) SaveMember(teamMember *model.TeamMember, maxUsersPerTeam int) (*model.TeamMember, *model.AppError) {
+	member, err := s.TeamStore.SaveMember(teamMember, maxUsersPerTeam)
+	if err == nil {
+		s.rootStore.indexUserFromID(member.UserId)
+	}
+	return member, err
+}
+
+func (s SearchTeamStore) UpdateMember(teamMember *model.TeamMember) (*model.TeamMember, *model.AppError) {
+	member, err := s.TeamStore.UpdateMember(teamMember)
+	if err == nil {
+		s.rootStore.indexUserFromID(member.UserId)
+	}
+	return member, err
+}
+
+func (s SearchTeamStore) RemoveMember(teamId string, userId string) *model.AppError {
+	err := s.TeamStore.RemoveMember(teamId, userId)
+	if err == nil {
+		s.rootStore.indexUserFromID(userId)
+	}
+	return err
+}
+
+func (s SearchTeamStore) RemoveAllMembersByUser(userId string) *model.AppError {
+	err := s.TeamStore.RemoveAllMembersByUser(userId)
+	if err == nil {
+		s.rootStore.indexUserFromID(userId)
+	}
+	return err
+}
--- a/store/searchlayer/user_layer.go
+++ b/store/searchlayer/user_layer.go
@@ -0,0 +1,192 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package searchlayer
+
+import (
+	"strings"
+
+	"github.com/mattermost/mattermost-server/v5/mlog"
+	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/services/searchengine"
+	"github.com/mattermost/mattermost-server/v5/store"
+)
+
+type SearchUserStore struct {
+	store.UserStore
+	rootStore *SearchStore
+}
+
+func (s *SearchUserStore) deleteUserIndex(user *model.User) {
+	for _, engine := range s.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsIndexingEnabled() {
+			go (func(engineCopy searchengine.SearchEngineInterface) {
+				if err := engineCopy.DeleteUser(user); err != nil {
+					mlog.Error("Encountered error deleting user", mlog.String("user_id", user.Id), mlog.String("search_engine", engineCopy.GetName()), mlog.Err(err))
+					return
+				}
+				mlog.Debug("Removed user from the index in search engine", mlog.String("search_engine", engineCopy.GetName()), mlog.String("user_id", user.Id))
+			})(engine)
+		}
+	}
+}
+
+func (s *SearchUserStore) Search(teamId, term string, options *model.UserSearchOptions) ([]*model.User, *model.AppError) {
+	for _, engine := range s.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsSearchEnabled() {
+			listOfAllowedChannels, err := s.getListOfAllowedChannelsForTeam(teamId, options.ViewRestrictions)
+			if err != nil {
+				mlog.Error("Encountered error on Search.", mlog.String("search_engine", engine.GetName()), mlog.Err(err))
+				continue
+			}
+			if len(listOfAllowedChannels) == 0 {
+				return []*model.User{}, nil
+			}
+
+			usersIds, err := engine.SearchUsersInTeam(teamId, listOfAllowedChannels, term, options)
+			if err != nil {
+				continue
+			}
+
+			users, err := s.UserStore.GetProfileByIds(usersIds, nil, false)
+			if err != nil {
+				continue
+			}
+
+			mlog.Debug("Using the first available search engine", mlog.String("search_engine", engine.GetName()))
+			return users, nil
+		}
+	}
+	mlog.Debug("Using database search because no other search engine is available")
+	return s.UserStore.Search(teamId, term, options)
+}
+
+func (s *SearchUserStore) Update(user *model.User, trustedUpdateData bool) (*model.UserUpdate, *model.AppError) {
+	userUpdate, err := s.UserStore.Update(user, trustedUpdateData)
+
+	if err == nil {
+		s.rootStore.indexUser(userUpdate.New)
+	}
+	return userUpdate, err
+}
+
+func (s *SearchUserStore) Save(user *model.User) (*model.User, *model.AppError) {
+	nuser, err := s.UserStore.Save(user)
+
+	if err == nil {
+		s.rootStore.indexUser(nuser)
+	}
+	return nuser, err
+}
+
+func (s *SearchUserStore) PermanentDelete(userId string) *model.AppError {
+	user, userErr := s.UserStore.Get(userId)
+	if userErr != nil {
+		mlog.Error("Encountered error deleting user", mlog.String("user_id", userId), mlog.Err(userErr))
+	}
+	err := s.UserStore.PermanentDelete(userId)
+	if err == nil && userErr == nil {
+		s.deleteUserIndex(user)
+	}
+	return err
+}
+
+func (s *SearchUserStore) autocompleteUsersInChannelByEngine(engine searchengine.SearchEngineInterface, teamId, channelId, term string, options *model.UserSearchOptions) (*model.UserAutocompleteInChannel, *model.AppError) {
+	var err *model.AppError
+	uchanIds := []string{}
+	nuchanIds := []string{}
+	if options.ListOfAllowedChannels != nil && !strings.Contains(strings.Join(options.ListOfAllowedChannels, "."), channelId) {
+		nuchanIds, err = engine.SearchUsersInTeam(teamId, options.ListOfAllowedChannels, term, options)
+	} else {
+		uchanIds, nuchanIds, err = engine.SearchUsersInChannel(teamId, channelId, options.ListOfAllowedChannels, term, options)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	uchan := make(chan store.StoreResult, 1)
+	go func() {
+		users, err := s.UserStore.GetProfileByIds(uchanIds, nil, false)
+		uchan <- store.StoreResult{Data: users, Err: err}
+		close(uchan)
+	}()
+
+	nuchan := make(chan store.StoreResult, 1)
+	go func() {
+		users, err := s.UserStore.GetProfileByIds(nuchanIds, nil, false)
+		nuchan <- store.StoreResult{Data: users, Err: err}
+		close(nuchan)
+	}()
+
+	autocomplete := &model.UserAutocompleteInChannel{}
+
+	result := <-uchan
+	if result.Err != nil {
+		return nil, result.Err
+	}
+	inUsers := result.Data.([]*model.User)
+	autocomplete.InChannel = inUsers
+
+	result = <-nuchan
+	if result.Err != nil {
+		return nil, result.Err
+	}
+	outUsers := result.Data.([]*model.User)
+	autocomplete.OutOfChannel = outUsers
+
+	return autocomplete, nil
+}
+
+func (s *SearchUserStore) getListOfAllowedChannelsForTeam(teamId string, viewRestrictions *model.ViewUsersRestrictions) ([]string, *model.AppError) {
+	var listOfAllowedChannels []string
+	if viewRestrictions == nil || strings.Contains(strings.Join(viewRestrictions.Teams, "."), teamId) {
+		channels, err := s.rootStore.Channel().GetTeamChannels(teamId)
+		if err != nil {
+			return nil, err
+		}
+		channelIds := []string{}
+		for _, channel := range *channels {
+			channelIds = append(channelIds, channel.Id)
+		}
+
+		return channelIds, nil
+	}
+
+	channels, err := s.rootStore.Channel().GetChannelsByIds(viewRestrictions.Channels, false)
+	if err != nil {
+		return nil, err
+	}
+	for _, c := range channels {
+		if c.TeamId == teamId {
+			listOfAllowedChannels = append(listOfAllowedChannels, c.Id)
+		}
+	}
+
+	return listOfAllowedChannels, nil
+}
+
+func (s *SearchUserStore) AutocompleteUsersInChannel(teamId, channelId, term string, options *model.UserSearchOptions) (*model.UserAutocompleteInChannel, *model.AppError) {
+	for _, engine := range s.rootStore.searchEngine.GetActiveEngines() {
+		if engine.IsAutocompletionEnabled() {
+			listOfAllowedChannels, err := s.getListOfAllowedChannelsForTeam(teamId, options.ViewRestrictions)
+			if err != nil {
+				mlog.Error("Encountered error on AutocompleteUsersInChannel.", mlog.String("search_engine", engine.GetName()), mlog.Err(err))
+				continue
+			}
+			if len(listOfAllowedChannels) == 0 {
+				return &model.UserAutocompleteInChannel{}, nil
+			}
+			options.ListOfAllowedChannels = listOfAllowedChannels
+			autocomplete, err := s.autocompleteUsersInChannelByEngine(engine, teamId, channelId, term, options)
+			if err != nil {
+				mlog.Error("Encountered error on AutocompleteUsersInChannel.", mlog.String("search_engine", engine.GetName()), mlog.Err(err))
+				continue
+			}
+			mlog.Debug("Using the first available search engine", mlog.String("search_engine", engine.GetName()))
+			return autocomplete, err
+		}
+	}
+
+	mlog.Debug("Using database search because no other search engine is available")
+	return s.UserStore.AutocompleteUsersInChannel(teamId, channelId, term, options)
+}