Remove the remaining fields from *app.Server (#19113)

We move these fields to Channels:
```
uploadLockMapMut sync.Mutex
uploadLockMap    map[string]bool
imgDecoder *imaging.Decoder
imgEncoder *imaging.Encoder
dndTaskMut sync.Mutex
dndTask    *model.ScheduledTask
```

I think this PR should conclue the initial phase
of migrating stuff from Server to Channels.

The remaining task would be to focus on continue
to create the remaining services from the
common things like users, teams, push notifications,
clustering for other products to consume.

https://community-daily.mattermost.com/boards/workspace/zyoahc9uapdn3xdptac6jb69ic/285b80a3-257d-41f6-8cf4-ed80ca9d92e5/495cdb4d-c13a-4992-8eb9-80cfee2819a4/87df1e15-588e-49ff-8bd1-ffa9651b8c82

```release-note
NONE
```

app/brand.go

@@ -32,13 +32,13 @@ func (a *App) SaveBrandImage(imageData *multipart.FileHeader) *model.AppError {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.check_image_limits.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 
-	img, _, err := a.ch.srv.imgDecoder.Decode(file)
+	img, _, err := a.ch.imgDecoder.Decode(file)
 	if err != nil {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.decode.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
 
 	buf := new(bytes.Buffer)
-	err = a.ch.srv.imgEncoder.EncodePNG(buf, img)
+	err = a.ch.imgEncoder.EncodePNG(buf, img)
 	if err != nil {
 		return model.NewAppError("SaveBrandImage", "brand.save_brand_image.encode.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}

app/channels.go

@@ -4,9 +4,11 @@
 package app
 
 import (
+	"runtime"
 	"sync"
 	"sync/atomic"
 
+	"github.com/mattermost/mattermost-server/v6/app/imaging"
 	"github.com/mattermost/mattermost-server/v6/app/request"
 	"github.com/mattermost/mattermost-server/v6/einterfaces"
 	"github.com/mattermost/mattermost-server/v6/model"
@@ -45,6 +47,18 @@ type Channels struct {
 	Compliance       einterfaces.ComplianceInterface
 	DataRetention    einterfaces.DataRetentionInterface
 	MessageExport    einterfaces.MessageExportInterface
+
+	// These are used to prevent concurrent upload requests
+	// for a given upload session which could cause inconsistencies
+	// and data corruption.
+	uploadLockMapMut sync.Mutex
+	uploadLockMap    map[string]bool
+
+	imgDecoder *imaging.Decoder
+	imgEncoder *imaging.Encoder
+
+	dndTaskMut sync.Mutex
+	dndTask    *model.ScheduledTask
 }
 
 func init() {
@@ -55,8 +69,9 @@ func init() {
 
 func NewChannels(s *Server) (*Channels, error) {
 	ch := &Channels{
-		srv:        s,
+		srv:           s,
-		imageProxy: imageproxy.MakeImageProxy(s, s.httpService, s.Log),
+		imageProxy:    imageproxy.MakeImageProxy(s, s.httpService, s.Log),
+		uploadLockMap: map[string]bool{},
 	}
 	// We are passing a partially filled Channels struct so that the enterprise
 	// methods can have access to app methods.
@@ -75,6 +90,20 @@ func NewChannels(s *Server) (*Channels, error) {
 		ch.AccountMigration = accountMigrationInterface(New(ServerConnector(ch)))
 	}
 
+	var imgErr error
+	ch.imgDecoder, imgErr = imaging.NewDecoder(imaging.DecoderOptions{
+		ConcurrencyLevel: runtime.NumCPU(),
+	})
+	if imgErr != nil {
+		return nil, errors.Wrap(imgErr, "failed to create image decoder")
+	}
+	ch.imgEncoder, imgErr = imaging.NewEncoder(imaging.EncoderOptions{
+		ConcurrencyLevel: runtime.NumCPU(),
+	})
+	if imgErr != nil {
+		return nil, errors.Wrap(imgErr, "failed to create image encoder")
+	}
+
 	// Setup routes.
 	pluginsRoute := ch.srv.Router.PathPrefix("/plugins/{plugin_id:[A-Za-z0-9\\_\\-\\.]+}").Subrouter()
 	pluginsRoute.HandleFunc("", ch.ServePluginRequest)
@@ -109,6 +138,13 @@ func (ch *Channels) Start() error {
 
 func (ch *Channels) Stop() error {
 	ch.ShutDownPlugins()
+
+	ch.dndTaskMut.Lock()
+	if ch.dndTask != nil {
+		ch.dndTask.Cancel()
+	}
+	ch.dndTaskMut.Unlock()
+
 	return nil
 }
 

app/file.go

@@ -703,8 +703,8 @@ func (a *App) UploadFileX(c *request.Context, channelID, name string, input io.R
 		Input:       input,
 		maxFileSize: *a.Config().FileSettings.MaxFileSize,
 		maxImageRes: *a.Config().FileSettings.MaxImageResolution,
-		imgDecoder:  a.ch.srv.imgDecoder,
+		imgDecoder:  a.ch.imgDecoder,
-		imgEncoder:  a.ch.srv.imgEncoder,
+		imgEncoder:  a.ch.imgEncoder,
 	}
 	for _, o := range opts {
 		o(t)
@@ -1040,7 +1040,7 @@ func (a *App) HandleImages(previewPathList []string, thumbnailPathList []string,
 	wg := new(sync.WaitGroup)
 
 	for i := range fileData {
-		img, release, err := prepareImage(a.ch.srv.imgDecoder, bytes.NewReader(fileData[i]))
+		img, release, err := prepareImage(a.ch.imgDecoder, bytes.NewReader(fileData[i]))
 		if err != nil {
 			mlog.Debug("Failed to prepare image", mlog.Err(err))
 			continue
@@ -1088,7 +1088,7 @@ func prepareImage(imgDecoder *imaging.Decoder, imgData io.ReadSeeker) (img image
 
 func (a *App) generateThumbnailImage(img image.Image, thumbnailPath string) {
 	var buf bytes.Buffer
-	if err := a.ch.srv.imgEncoder.EncodeJPEG(&buf, imaging.GenerateThumbnail(img, imageThumbnailWidth, imageThumbnailHeight), jpegEncQuality); err != nil {
+	if err := a.ch.imgEncoder.EncodeJPEG(&buf, imaging.GenerateThumbnail(img, imageThumbnailWidth, imageThumbnailHeight), jpegEncQuality); err != nil {
 		mlog.Error("Unable to encode image as jpeg", mlog.String("path", thumbnailPath), mlog.Err(err))
 		return
 	}
@@ -1103,7 +1103,7 @@ func (a *App) generatePreviewImage(img image.Image, previewPath string) {
 	var buf bytes.Buffer
 	preview := imaging.GeneratePreview(img, imagePreviewWidth)
 
-	if err := a.ch.srv.imgEncoder.EncodeJPEG(&buf, preview, jpegEncQuality); err != nil {
+	if err := a.ch.imgEncoder.EncodeJPEG(&buf, preview, jpegEncQuality); err != nil {
 		mlog.Error("Unable to encode image as preview jpg", mlog.Err(err), mlog.String("path", previewPath))
 		return
 	}
@@ -1124,7 +1124,7 @@ func (a *App) generateMiniPreview(fi *model.FileInfo) {
 			return
 		}
 		defer file.Close()
-		img, release, err := prepareImage(a.ch.srv.imgDecoder, file)
+		img, release, err := prepareImage(a.ch.imgDecoder, file)
 		if err != nil {
 			mlog.Debug("generateMiniPreview: prepareImage failed", mlog.Err(err),
 				mlog.String("fileinfo_id", fi.Id), mlog.String("channel_id", fi.ChannelId),

app/server.go

@@ -38,7 +38,6 @@ import (
 
 	"github.com/mattermost/mattermost-server/v6/app/email"
 	"github.com/mattermost/mattermost-server/v6/app/featureflag"
-	"github.com/mattermost/mattermost-server/v6/app/imaging"
 	"github.com/mattermost/mattermost-server/v6/app/request"
 	"github.com/mattermost/mattermost-server/v6/app/teams"
 	"github.com/mattermost/mattermost-server/v6/app/users"
@@ -174,23 +173,11 @@ type Server struct {
 
 	tracer *tracing.Tracer
 
-	// These are used to prevent concurrent upload requests
-	// for a given upload session which could cause inconsistencies
-	// and data corruption.
-	uploadLockMapMut sync.Mutex
-	uploadLockMap    map[string]bool
-
 	featureFlagSynchronizer      *featureflag.Synchronizer
 	featureFlagStop              chan struct{}
 	featureFlagStopped           chan struct{}
 	featureFlagSynchronizerMutex sync.Mutex
 
-	imgDecoder *imaging.Decoder
-	imgEncoder *imaging.Encoder
-
-	dndTaskMut sync.Mutex
-	dndTask    *model.ScheduledTask
-
 	products map[string]Product
 }
 
@@ -207,7 +194,6 @@ func NewServer(options ...Option) (*Server, error) {
 		},
 		licenseListeners: map[string]func(*model.License, *model.License){},
 		hashSeed:         maphash.MakeSeed(),
-		uploadLockMap:    map[string]bool{},
 		timezones:        timezones.New(),
 		products:         make(map[string]Product),
 	}
@@ -492,20 +478,6 @@ func NewServer(options ...Option) (*Server, error) {
 
 	s.setupFeatureFlags()
 
-	var imgErr error
-	s.imgDecoder, imgErr = imaging.NewDecoder(imaging.DecoderOptions{
-		ConcurrencyLevel: runtime.NumCPU(),
-	})
-	if imgErr != nil {
-		return nil, errors.Wrap(imgErr, "failed to create image decoder")
-	}
-	s.imgEncoder, imgErr = imaging.NewEncoder(imaging.EncoderOptions{
-		ConcurrencyLevel: runtime.NumCPU(),
-	})
-	if imgErr != nil {
-		return nil, errors.Wrap(imgErr, "failed to create image encoder")
-	}
-
 	s.initJobs()
 
 	s.clusterLeaderListenerId = s.AddClusterLeaderChangedListener(func() {
@@ -1027,12 +999,6 @@ func (s *Server) Shutdown() {
 		}
 	}
 
-	s.dndTaskMut.Lock()
-	if s.dndTask != nil {
-		s.dndTask.Cancel()
-	}
-	s.dndTaskMut.Unlock()
-
 	mlog.Info("Server stopped")
 
 	// Stop products.
@@ -2257,18 +2223,18 @@ func (s *Server) ReadFile(path string) ([]byte, *model.AppError) {
 }
 
 func createDNDStatusExpirationRecurringTask(a *App) {
-	a.ch.srv.dndTaskMut.Lock()
+	a.ch.dndTaskMut.Lock()
-	a.ch.srv.dndTask = model.CreateRecurringTaskFromNextIntervalTime("Unset DND Statuses", a.UpdateDNDStatusOfUsers, 5*time.Minute)
+	a.ch.dndTask = model.CreateRecurringTaskFromNextIntervalTime("Unset DND Statuses", a.UpdateDNDStatusOfUsers, 5*time.Minute)
-	a.ch.srv.dndTaskMut.Unlock()
+	a.ch.dndTaskMut.Unlock()
 }
 
 func cancelDNDStatusExpirationRecurringTask(a *App) {
-	a.ch.srv.dndTaskMut.Lock()
+	a.ch.dndTaskMut.Lock()
-	if a.ch.srv.dndTask != nil {
+	if a.ch.dndTask != nil {
-		a.ch.srv.dndTask.Cancel()
+		a.ch.dndTask.Cancel()
-		a.ch.srv.dndTask = nil
+		a.ch.dndTask = nil
 	}
-	a.ch.srv.dndTaskMut.Unlock()
+	a.ch.dndTaskMut.Unlock()
 }
 
 func runDNDStatusExpireJob(a *App) {

app/slack.go

@@ -41,7 +41,7 @@ func (a *App) SlackImport(c *request.Context, fileData multipart.File, fileSize
 		InvalidateAllCaches:    func() { a.ch.srv.InvalidateAllCaches() },
 		MaxPostSize:            func() int { return a.ch.srv.MaxPostSize() },
 		PrepareImage: func(fileData []byte) (image.Image, func(), error) {
-			img, release, err := prepareImage(a.ch.srv.imgDecoder, bytes.NewReader(fileData))
+			img, release, err := prepareImage(a.ch.imgDecoder, bytes.NewReader(fileData))
 			if err != nil {
 				return nil, nil, err
 			}

app/team.go

@@ -1848,7 +1848,7 @@ func (a *App) SetTeamIconFromFile(team *model.Team, file io.Reader) *model.AppEr
 	img = imaging.FillCenter(img, teamIconWidthAndHeight, teamIconWidthAndHeight)
 
 	buf := new(bytes.Buffer)
-	err = a.Srv().imgEncoder.EncodePNG(buf, img)
+	err = a.ch.imgEncoder.EncodePNG(buf, img)
 	if err != nil {
 		return model.NewAppError("SetTeamIcon", "api.team.set_team_icon.encode.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}

app/upload.go

@@ -166,23 +166,23 @@ func (a *App) GetUploadSessionsForUser(userID string) ([]*model.UploadSession, *
 func (a *App) UploadData(c *request.Context, us *model.UploadSession, rd io.Reader) (*model.FileInfo, *model.AppError) {
 	// prevent more than one caller to upload data at the same time for a given upload session.
 	// This is to avoid possible inconsistencies.
-	a.Srv().uploadLockMapMut.Lock()
+	a.ch.uploadLockMapMut.Lock()
-	locked := a.Srv().uploadLockMap[us.Id]
+	locked := a.ch.uploadLockMap[us.Id]
 	if locked {
 		// session lock is already taken, return error.
-		a.Srv().uploadLockMapMut.Unlock()
+		a.ch.uploadLockMapMut.Unlock()
 		return nil, model.NewAppError("UploadData", "app.upload.upload_data.concurrent.app_error",
 			nil, "", http.StatusBadRequest)
 	}
 	// grab the session lock.
-	a.Srv().uploadLockMap[us.Id] = true
+	a.ch.uploadLockMap[us.Id] = true
-	a.Srv().uploadLockMapMut.Unlock()
+	a.ch.uploadLockMapMut.Unlock()
 
 	// reset the session lock on exit.
 	defer func() {
-		a.Srv().uploadLockMapMut.Lock()
+		a.ch.uploadLockMapMut.Lock()
-		delete(a.Srv().uploadLockMap, us.Id)
+		delete(a.ch.uploadLockMap, us.Id)
-		a.Srv().uploadLockMapMut.Unlock()
+		a.ch.uploadLockMapMut.Unlock()
 	}()
 
 	// fetch the session from store to check for inconsistencies.

app/user.go

@@ -767,7 +767,7 @@ func (a *App) SetProfileImageFromMultiPartFile(userID string, file multipart.Fil
 
 func (a *App) AdjustImage(file io.Reader) (*bytes.Buffer, *model.AppError) {
 	// Decode image into Image object
-	img, _, err := a.ch.srv.imgDecoder.Decode(file)
+	img, _, err := a.ch.imgDecoder.Decode(file)
 	if err != nil {
 		return nil, model.NewAppError("SetProfileImage", "api.user.upload_profile_user.decode.app_error", nil, err.Error(), http.StatusBadRequest)
 	}
@@ -780,7 +780,7 @@ func (a *App) AdjustImage(file io.Reader) (*bytes.Buffer, *model.AppError) {
 	img = imaging.FillCenter(img, profileWidthAndHeight, profileWidthAndHeight)
 
 	buf := new(bytes.Buffer)
-	err = a.ch.srv.imgEncoder.EncodePNG(buf, img)
+	err = a.ch.imgEncoder.EncodePNG(buf, img)
 	if err != nil {
 		return nil, model.NewAppError("SetProfileImage", "api.user.upload_profile_user.encode.app_error", nil, err.Error(), http.StatusInternalServerError)
 	}