Requested changes.

Added Per Image Lock on conversion, to prevent multiple threads from processing the same image at the same time.

API/Entities/Enums/EncodeFormat.cs

@@ -1,16 +1,16 @@
-using System.ComponentModel;
+using System.ComponentModel;
 
 namespace API.Entities.Enums;
 
-public enum EncodeFormat 
+public enum EncodeFormat
 {
     [Description("PNG")]
     PNG = 0,
     [Description("WebP")]
     WEBP = 1,
     [Description("AVIF")]
     AVIF = 2,
-    //Internal Use
+    /// Internal Use
     [Description("JPEG")]
     JPEG = 3
 }

API/Extensions/HttpExtensions.cs

@@ -80,28 +80,30 @@ public static List<string> SupportedImageTypesFromRequest(this HttpRequest reque
 
         List<string> supportedExtensions = new List<string>();
 
-        //Add default extensions supported by all browsers.
+        // Add default extensions supported by all browsers.
         supportedExtensions.AddRange(Parser.UniversalFileImageExtensionArray);
-        //Browser add specific image mime types, when the image type is not a global standard, browser specify the specific image type in the accept header.
-        //Let's reuse that to identify the additional image types supported by the browser.
-        foreach (string v in split)
+
+        // Browser add specific image mime types, when the image type is not a global standard, browser specify the specific image type in the accept header.
+        // Let's reuse that to identify the additional image types supported by the browser.
+        foreach (var v in split)
         {
             if (v.StartsWith("image/", StringComparison.InvariantCultureIgnoreCase))
             {
-                string mimeimagepart = v.Substring(6).ToLowerInvariant();
-                if (mimeimagepart.StartsWith("*")) continue;
-                if (Parser.NonUniversalSupportedMimeMappings.ContainsKey(mimeimagepart))
+                var mimeImagePart = v.Substring(6).ToLowerInvariant();
+                if (mimeImagePart.StartsWith("*")) continue;
+                if (Parser.NonUniversalSupportedMimeMappings.ContainsKey(mimeImagePart))
                 {
-                    Parser.NonUniversalSupportedMimeMappings[mimeimagepart].ForEach(x => AddExtension(supportedExtensions, x));
+                    Parser.NonUniversalSupportedMimeMappings[mimeImagePart].ForEach(x => AddExtension(supportedExtensions, x));
                 }
-                else if (mimeimagepart == "svg+xml")
+                else if (mimeImagePart == "svg+xml")
                 {
                     AddExtension(supportedExtensions, "svg");
                 }
                 else
-                    AddExtension(supportedExtensions, mimeimagepart);
+                    AddExtension(supportedExtensions, mimeImagePart);
             }
         }
+
         return supportedExtensions;
     }
 }

API/Services/ImageService.cs

@@ -1,11 +1,15 @@
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Drawing;
 using System.IO;
 using System.Linq;
 using System.Numerics;
+using System.Security.Cryptography;
+using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading;
 using System.Threading.Tasks;
 using API.Constants;
 using API.DTOs;
@@ -155,19 +159,13 @@ public interface IImageService
 public class ImageService : IImageService
 {
     public const string Name = "ImageService";
-    private readonly ILogger<ImageService> _logger;
-    private readonly IDirectoryService _directoryService;
-    private readonly IEasyCachingProviderFactory _cacheFactory;
-    private readonly IImageFactory _imageFactory;
     public const string ChapterCoverImageRegex = @"v\d+_c\d+";
     public const string SeriesCoverImageRegex = @"series\d+";
     public const string CollectionTagCoverImageRegex = @"tag\d+";
     public const string ReadingListCoverImageRegex = @"readinglist\d+";
-
     private const double WhiteThreshold = 0.95; // Colors with lightness above this are considered too close to white
     private const double BlackThreshold = 0.25; // Colors with lightness below this are considered too close to black
 
-
     /// <summary>
     /// Width of the Thumbnail generation
     /// </summary>
@@ -181,6 +179,10 @@ public class ImageService : IImageService
     /// </summary>
     public const int LibraryThumbnailWidth = 32;
 
+    private readonly ILogger<ImageService> _logger;
+    private readonly IDirectoryService _directoryService;
+    private readonly IEasyCachingProviderFactory _cacheFactory;
+    private readonly IImageFactory _imageFactory;
 
     private static readonly string[] ValidIconRelations = {
         "icon",
@@ -197,6 +199,21 @@ public class ImageService : IImageService
         ["https://app.plex.tv"] = "https://plex.tv"
     };
 
+
+
+    private static NamedMonitor _lock = new NamedMonitor();
+    /// <summary>
+    /// Represents a named monitor that provides thread-safe access to objects based on their names.
+    /// </summary>
+    class NamedMonitor
+    {
+        readonly ConcurrentDictionary<string, object> _dictionary = new ConcurrentDictionary<string, object>();
+
+        public object this[string name] => _dictionary.GetOrAdd(name, _ => new object());
+    }
+
+
+
     /// <summary>
     /// Initializes a new instance of the <see cref="ImageService"/> class.
     /// </summary>
@@ -229,7 +246,7 @@ public void ExtractImages(string? fileFilePath, string targetDirectory, int file
                 Tasks.Scanner.Parser.Parser.ImageFileExtensions);
         }
     }
-    
+
     /// <summary>
     /// Creates a thumbnail image from the specified image with the given width and height.
     /// If the image aspect ratio is significantly different from the target aspect ratio, it will be context aware cropped to fit.
@@ -332,12 +349,10 @@ public string WriteCoverThumbnail(Stream stream, string fileName, string outputD
         try
         {
             thumbnail.Save(_directoryService.FileSystem.Path.Join(outputDirectory, filename), encodeFormat, quality);
-            return filename;
-        }
-        catch (Exception)
-        {
-            return string.Empty; //IDK?
         }
+        catch (Exception) {/* Swallow exception */}
+
+        return filename;
     }
     /// <inheritdoc/>
     public string WriteCoverThumbnail(string sourceFile, string fileName, string outputDirectory, EncodeFormat encodeFormat, CoverImageSize size = CoverImageSize.Default, int quality = 100)
@@ -351,6 +366,7 @@ public string WriteCoverThumbnail(string sourceFile, string fileName, string out
             _directoryService.FileSystem.File.Delete(_directoryService.FileSystem.Path.Join(outputDirectory, filename));
         } catch (Exception) {/* Swallow exception */}
         thumbnail.Save(_directoryService.FileSystem.Path.Join(outputDirectory, filename), encodeFormat, quality);
+
         return filename;
     }
     /// <inheritdoc/>
@@ -361,6 +377,7 @@ public async Task<string> ConvertToEncodingFormat(string filePath, string output
         var outputFile = Path.Join(outputPath, fileName + encodeFormat.GetExtension());
         using var sourceImage = _imageFactory.Create(filePath);
         await sourceImage.SaveAsync(outputFile, encodeFormat, quality).ConfigureAwait(false);
+
         return outputFile;
     }
 
@@ -369,9 +386,7 @@ public Task<bool> IsImage(string filePath)
     {
         try
         {
-            var result= _imageFactory.GetDimensions(filePath);
-            if (result!=null)
-                return Task.FromResult(true);
+            return Task.FromResult(_imageFactory.GetDimensions(filePath) != null);
         }
         catch (Exception)
         {
@@ -521,7 +536,7 @@ public async Task<string> DownloadPublisherImageAsync(string publisherName, Enco
 
         return (null, null);
     }
-    
+
     private static bool IsColorCloseToWhiteOrBlack(Vector3 color)
     {
         var (_, _, lightness) = RgbToHsl(color);
@@ -690,26 +705,41 @@ public ColorScape CalculateColorScape(string sourceFile)
     }
     private bool CheckDirectSupport(string filename, List<string> supportedImageFormats)
     {
-        if (supportedImageFormats == null)
-            return false;
+        if (supportedImageFormats == null) return false;
+
         string ext = Path.GetExtension(filename).ToLowerInvariant().Substring(1);
         return supportedImageFormats.Contains(ext);
     }
+
+
     /// <inheritdoc/>
     public string ReplaceImageFileFormat(string filename, List<string> supportedImageFormats = null, EncodeFormat format = EncodeFormat.JPEG, int quality = 99)
     {
-        if (CheckDirectSupport(filename, supportedImageFormats))
-            return filename;
+        if (CheckDirectSupport(filename, supportedImageFormats)) return filename;
+
         Match m = Regex.Match(Path.GetExtension(filename), Parser.NonUniversalFileImageExtensions, RegexOptions.IgnoreCase, Parser.RegexTimeout);
-        if (!m.Success)
-            return filename;
-        var sw = Stopwatch.StartNew();
+        if (!m.Success) return filename;
+
         string destination = Path.ChangeExtension(filename, format.GetExtension().Substring(1));
 
-        using var sourceImage = _imageFactory.Create(filename);
-        sourceImage.Save(destination, format, quality);
-        File.Delete(filename);
-        _logger.LogDebug("Image converted from '{Extension}' to '{format.GetExtension()}' in {ElapsedMilliseconds} milliseconds", Path.GetExtension(filename), sw.ElapsedMilliseconds);
+        // Adding a lock per destination, sometimes web ui triggers same image loading at the ~ same time.
+        // So, if other thread is already processing the image, we should wait for it to finish, then the File.Exists(destination) will early exit.
+        // This exists, to prevent multiple threads from processing the same image at the same time.
+        lock (_lock[destination])
+        {
+            if (File.Exists(destination))
+            {
+                // Destination already exist, the conversion was already made.
+                return destination;
+            }
+            using var sourceImage = _imageFactory.Create(filename);
+            sourceImage.Save(destination, format, quality);
+            try
+            {
+                File.Delete(filename);
+            }
+            catch (Exception) { /* Swallow Exception */ }
+        }
         return destination;
     }