Merge branch 'master' of https://github.com/rs/SDWebImage into 5.x

* 'master' of https://github.com/rs/SDWebImage:
  Fix the getSize method which use the default file manager instead of current file manager
  Deprecate the sd_setImageWithPreviousCachedImageWithURL with the specify options to achieve this usage
  Use the @synchronized to access NSURLCache to fix the potential thread-safe problem, also fix that we always use shared cache but not follow session's configuration

SDWebImage/SDImageCache.m

@@ -627,7 +627,7 @@ FOUNDATION_STATIC_INLINE NSUInteger SDCacheCostForImage(UIImage *image) {
         NSDirectoryEnumerator *fileEnumerator = [_fileManager enumeratorAtPath:self.diskCachePath];
         for (NSString *fileName in fileEnumerator) {
             NSString *filePath = [self.diskCachePath stringByAppendingPathComponent:fileName];
-            NSDictionary<NSString *, id> *attrs = [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil];
+            NSDictionary<NSString *, id> *attrs = [_fileManager attributesOfItemAtPath:filePath error:nil];
             size += [attrs fileSize];
         }
     });

SDWebImage/SDWebImageDownloaderOperation.m

@@ -135,14 +135,6 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
             }];
         }
 #endif
-        if (self.options & SDWebImageDownloaderIgnoreCachedResponse) {
-            // Grab the cached data for later check
-            NSCachedURLResponse *cachedResponse = [[NSURLCache sharedURLCache] cachedResponseForRequest:self.request];
-            if (cachedResponse) {
-                self.cachedData = cachedResponse.data;
-            }
-        }
-        
         NSURLSession *session = self.unownedSession;
         if (!self.unownedSession) {
             NSURLSessionConfiguration *sessionConfig = [NSURLSessionConfiguration defaultSessionConfiguration];
@@ -159,6 +151,22 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
             session = self.ownedSession;
         }
         
+        if (self.options & SDWebImageDownloaderIgnoreCachedResponse) {
+            // Grab the cached data for later check
+            NSURLCache *URLCache = session.configuration.URLCache;
+            if (!URLCache) {
+                URLCache = [NSURLCache sharedURLCache];
+            }
+            NSCachedURLResponse *cachedResponse;
+            // NSURLCache's `cachedResponseForRequest:` is not thread-safe, see https://developer.apple.com/documentation/foundation/nsurlcache#2317483
+            @synchronized (URLCache) {
+                cachedResponse = [URLCache cachedResponseForRequest:self.request];
+            }
+            if (cachedResponse) {
+                self.cachedData = cachedResponse.data;
+            }
+        }
+        
         self.dataTask = [session dataTaskWithRequest:self.request];
         self.executing = YES;
     }

SDWebImage/UIImageView+WebCache.h

@@ -155,7 +155,9 @@
                  completed:(nullable SDExternalCompletionBlock)completedBlock;
 
 /**
- * Set the imageView `image` with an `url` and optionally a placeholder image.
+ * Set the imageView `image` with an `url` and custom options. The placeholder image is from previous cached image and will use the provided one instead if the query failed.
+ * This method was designed to ensure that placeholder and query cache process happened in the same runloop to avoid flashing on cell during two `setImage:` call. But it's really misunderstanding and deprecated.
+ * This can be done by using `sd_setImageWithURL:` with `SDWebImageQueryDiskSync`. But take care that if the memory cache missed, query disk cache synchronously may reduce the frame rate
  *
  * The download is asynchronous and cached.
  *
@@ -169,12 +171,13 @@
  *                       is nil and the second parameter may contain an NSError. The third parameter is a Boolean
  *                       indicating if the image was retrieved from the local cache or from the network.
  *                       The fourth parameter is the original image url.
+ * @deprecated consider using `SDWebImageQueryDiskSync` options with `sd_setImageWithURL:` instead
  */
 - (void)sd_setImageWithPreviousCachedImageWithURL:(nullable NSURL *)url
                                  placeholderImage:(nullable UIImage *)placeholder
                                           options:(SDWebImageOptions)options
                                          progress:(nullable SDWebImageDownloaderProgressBlock)progressBlock
-                                        completed:(nullable SDExternalCompletionBlock)completedBlock;
+                                        completed:(nullable SDExternalCompletionBlock)completedBlock __deprecated_msg("This method is misunderstanding and deprecated, consider using `SDWebImageQueryDiskSync` options with `sd_setImageWithURL:` instead");
 
 #if SD_UIKIT