Add option to generate image thumbnails during generate (#4602)

* Add option to generate image thumbnails
* Limit number of concurrent image thumbnail generation ops

graphql/schema/types/metadata.graphql

@@ -12,6 +12,7 @@ input GenerateMetadataInput {
   forceTranscodes: Boolean
   phashes: Boolean
   interactiveHeatmapsSpeeds: Boolean
+  imageThumbnails: Boolean
   clipPreviews: Boolean
 
   "scene ids to generate for"
@@ -48,6 +49,7 @@ type GenerateMetadataOptions {
   transcodes: Boolean
   phashes: Boolean
   interactiveHeatmapsSpeeds: Boolean
+  imageThumbnails: Boolean
   clipPreviews: Boolean
 }
 

internal/api/routes_image.go

@@ -46,8 +46,9 @@ func (rs imageRoutes) Routes() chi.Router {
 }
 
 func (rs imageRoutes) Thumbnail(w http.ResponseWriter, r *http.Request) {
+	mgr := manager.GetInstance()
 	img := r.Context().Value(imageKey).(*models.Image)
-	filepath := manager.GetInstance().Paths.Generated.GetThumbnailPath(img.Checksum, models.DefaultGthumbWidth)
+	filepath := mgr.Paths.Generated.GetThumbnailPath(img.Checksum, models.DefaultGthumbWidth)
 
 	// if the thumbnail doesn't exist, encode on the fly
 	exists, _ := fsutil.FileExists(filepath)
@@ -62,6 +63,11 @@ func (rs imageRoutes) Thumbnail(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 
+		// use the image thumbnail generate wait group to limit the number of concurrent thumbnail generation tasks
+		wg := &mgr.ImageThumbnailGenerateWaitGroup
+		wg.Add()
+		defer wg.Done()
+
 		clipPreviewOptions := image.ClipPreviewOptions{
 			InputArgs:  manager.GetInstance().Config.GetTranscodeInputArgs(),
 			OutputArgs: manager.GetInstance().Config.GetTranscodeOutputArgs(),

internal/manager/init.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/remeh/sizedwaitgroup"
 	"github.com/stashapp/stash/internal/desktop"
 	"github.com/stashapp/stash/internal/dlna"
 	"github.com/stashapp/stash/internal/log"
@@ -80,6 +81,8 @@ func Initialize(cfg *config.Config, l *log.Logger) (*Manager, error) {
 
 		Paths: mgrPaths,
 
+		ImageThumbnailGenerateWaitGroup: sizedwaitgroup.New(1),
+
 		JobManager:      initJobManager(cfg),
 		ReadLockManager: fsutil.NewReadLockManager(),
 

internal/manager/manager.go

@@ -10,6 +10,7 @@ import (
 	"runtime"
 	"time"
 
+	"github.com/remeh/sizedwaitgroup"
 	"github.com/stashapp/stash/internal/dlna"
 	"github.com/stashapp/stash/internal/log"
 	"github.com/stashapp/stash/internal/manager/config"
@@ -33,6 +34,10 @@ type Manager struct {
 	Config *config.Config
 	Logger *log.Logger
 
+	// ImageThumbnailGenerateWaitGroup is the global wait group image thumbnail generation
+	// It uses the parallel tasks setting from the configuration.
+	ImageThumbnailGenerateWaitGroup sizedwaitgroup.SizedWaitGroup
+
 	Paths *paths.Paths
 
 	FFMpeg        *ffmpeg.FFMpeg
@@ -107,6 +112,8 @@ func (s *Manager) RefreshConfig() {
 		if err := fsutil.EnsureDir(s.Paths.Generated.InteractiveHeatmap); err != nil {
 			logger.Warnf("could not create interactive heatmaps directory: %v", err)
 		}
+
+		s.ImageThumbnailGenerateWaitGroup.Size = cfg.GetParallelTasksWithAutoDetection()
 	}
 }