Added error indication file instead of thumbnail to avoid re-generation

of thumbnails that failed before.

FAQ.md

@@ -65,7 +65,7 @@ This can be fixed by automatically resizing the images on the server side by ena
 
     enablepreview = on
 
-It will take some time for the server to resize the image, but once the image has been resized, it will be cached in the same location as the thumbnails. Next time the image is viewed it will be balzing fast. 
+It will take some time for the server to resize the image, but once the image has been resized, it will be cached in the same location as the thumbnails. Next time the image is viewed it will be blazing fast. 
 
 The size of the preview images is set with the previewmaxside configuration parameter. To limit the height and width to 1000 pixels, set:
 

media.go

@@ -364,6 +364,15 @@ func (m *Media) thumbnailPath(relativeMediaPath string) (string, error) {
 	return m.getFullThumbPath(relativeThumbnailPath)
 }
 
+// errorIndicationPath returns the file path with the extension
+// replaced with err.
+func (m *Media) errorIndicationPath(anyPath string) string {
+	path, file := filepath.Split(anyPath)
+	ext := filepath.Ext(file)
+	file = strings.Replace(file, ext, ".err.txt", -1)
+	return filepath.Join(path, file)
+}
+
 // generateImageThumbnail generates a thumbnail from any of the supported
 // images. Will create necessary subdirectories in the thumbpath.
 func (m *Media) generateImageThumbnail(fullMediaPath, fullThumbPath string) error {
@@ -404,14 +413,24 @@ func (m *Media) generateThumbnail(relativeFilePath string) (string, error) {
 	if err == nil {
 		return thumbFileName, nil // Thumb already generated
 	}
+	errorIndicationFile := m.errorIndicationPath(thumbFileName)
+	_, err = os.Stat(errorIndicationFile) // Check if file exist
+	if err == nil {
+		// File has failed to be generated before, don't bother
+		// trying to re-generate it.
+		msg := fmt.Sprintf("Skipping generate thumbnail for %s since it has failed before.", 
+			relativeFilePath)
+		llog.Trace(msg)
+		return "", fmt.Errorf(msg)
+	}	
 
 	// No thumb exist. Create it
 	llog.Info("Creating new thumbnail for %s", relativeFilePath)
 	startTime := time.Now().UnixNano()
 	fullMediaPath, err := m.getFullMediaPath(relativeFilePath)
 	if err != nil {
 		llog.Error("%s", err)
-		return thumbFileName, err
+		return "", err
 	}
 	if m.isVideo(fullMediaPath) {
 		err = m.generateVideoThumbnail(fullMediaPath, thumbFileName)
@@ -420,7 +439,14 @@ func (m *Media) generateThumbnail(relativeFilePath string) (string, error) {
 	}
 	if err != nil {
 		llog.Error("%s", err)
-		return thumbFileName, err
+		// To avoid generate the file again, create an error indication file
+		errorFile, err2 := os.Create(errorIndicationFile)
+		if err2 == nil {
+			defer errorFile.Close()
+			errorFile.WriteString(err.Error())
+			llog.Info("Created: %s", errorIndicationFile)
+		}
+		return "", err
 	}
 	deltaTime := (time.Now().UnixNano() - startTime) / int64(time.Millisecond)
 	llog.Info("Thumbnail done for %s (conversion time: %d ms)",
@@ -565,9 +591,10 @@ func (m *Media) extractVideoScreenshot(inFilePath, outFilePath string) error {
 	cmd.Stdout = &stdout
 	cmd.Stderr = &stderr
 	err = cmd.Run()
-	if err != nil {
-		return fmt.Errorf("%s %s\nError: %s\nStdout: %s\nStderr: %s",
-			ffmpegCmd, strings.Join(ffmpegArgs, " "), err, stdout.String(), stderr.String())
+	_, outFileErr := os.Stat(outFilePath) 
+	if err != nil || outFileErr != nil {
+		return fmt.Errorf("%s %s\nStdout: %s\nStderr: %s",
+			ffmpegCmd, strings.Join(ffmpegArgs, " "), stdout.String(), stderr.String())
 	}
 	return nil
 }

media_test.go

@@ -343,13 +343,22 @@ func TestWriteThumbnail(t *testing.T) {
 	// Video - only if video is supported
 	if media.videoThumbnailSupport() {
 		tWriteThumbnail(t, media, "video.mp4", "tmpout/TestWriteThumbnail/video.jpg", false)
+
+		// Test invalid
+		tWriteThumbnail(t, media, "invalidvideo.mp4", "tmpout/TestWriteThumbnail/invalidvideo.jpg", true)
+		// Check that error indication file is created
+		assertFileExist(t, "", "tmpcache/TestWriteThumbnail/_invalidvideo.err.txt")
 	}
 
 	// Non existing file
 	tWriteThumbnail(t, media, "dont_exist.jpg", "tmpout/TestWriteThumbnail/dont_exist.jpg", true)
 
 	// Invalid file
 	tWriteThumbnail(t, media, "invalid.jpg", "tmpout/TestWriteThumbnail/invalid.jpg", true)
+	// Check that error indication file is created
+	assertFileExist(t, "", "tmpcache/TestWriteThumbnail/_invalid.err.txt")
+	// Generate again - just for coverage
+	tWriteThumbnail(t, media, "invalid.jpg", "tmpout/TestWriteThumbnail/invalid.jpg", true)
 
 	// Disable thumb cache
 	media = createMedia(box, "testmedia", "tmpcache/TestWriteThumbnail", false, false, false, true, false, 0)
@@ -415,7 +424,7 @@ func TestGenerateVideoThumbnail(t *testing.T) {
 	// Test some invalid
 	err := media.generateVideoThumbnail("nonexisting.mp4", tmp+"dont_matter.jpg")
 	assertExpectErr(t, "", err)
-	err = media.generateVideoThumbnail("invalidvideo.mp4", tmp+"dont_matter_png.jpg")
+	err = media.generateVideoThumbnail("invalidvideo.mp4", tmp+"/invalidvideo.jpg")
 	assertExpectErr(t, "", err)
 }