Merge pull request #3053 from kinarobin/fix-race-condition-when-using-transition

Fix race condition when use transition but canceling an operation

SDWebImage/Core/UIView+WebCache.h

@@ -34,6 +34,7 @@ typedef void(^SDSetImageBlock)(UIImage * _Nullable image, NSData * _Nullable ima
 /**
  * Get the current image operation key. Operation key is used to identify the different queries for one view instance (like UIButton).
  * See more about this in `SDWebImageContextSetImageOperationKey`.
+ * If you cancel current image load, the key will be set to nil.
  * @note You can use method `UIView+WebCacheOperation` to investigate different queries' operation.
  */
 @property (nonatomic, strong, readonly, nullable) NSString *sd_latestOperationKey;

SDWebImage/Core/UIView+WebCache.m

@@ -203,6 +203,7 @@ const int64_t SDWebImageProgressUnitCountUnknown = 1LL;
 
 - (void)sd_cancelCurrentImageLoad {
     [self sd_cancelImageLoadOperationWithKey:self.sd_latestOperationKey];
+    self.sd_latestOperationKey = nil;
 }
 
 - (void)sd_setImage:(UIImage *)image imageData:(NSData *)imageData basedOnClassOrViaCustomSetImageBlock:(SDSetImageBlock)setImageBlock cacheType:(SDImageCacheType)cacheType imageURL:(NSURL *)imageURL {
@@ -251,22 +252,38 @@ const int64_t SDWebImageProgressUnitCountUnknown = 1LL;
     if (transition) {
 #if SD_UIKIT
         [UIView transitionWithView:view duration:0 options:0 animations:^{
+            if (!view.sd_latestOperationKey) {
+                return;
+            }
             // 0 duration to let UIKit render placeholder and prepares block
             if (transition.prepares) {
                 transition.prepares(view, image, imageData, cacheType, imageURL);
             }
         } completion:^(BOOL finished) {
             [UIView transitionWithView:view duration:transition.duration options:transition.animationOptions animations:^{
+                if (!view.sd_latestOperationKey) {
+                    return;
+                }
                 if (finalSetImageBlock && !transition.avoidAutoSetImage) {
                     finalSetImageBlock(image, imageData, cacheType, imageURL);
                 }
                 if (transition.animations) {
                     transition.animations(view, image);
                 }
-            } completion:transition.completion];
+            } completion:^(BOOL finished) {
+                if (!view.sd_latestOperationKey) {
+                    return;
+                }
+                if (transition.completion) {
+                    transition.completion(finished);
+                }
+            }];
         }];
 #elif SD_MAC
         [NSAnimationContext runAnimationGroup:^(NSAnimationContext * _Nonnull prepareContext) {
+            if (!view.sd_latestOperationKey) {
+                return;
+            }
             // 0 duration to let AppKit render placeholder and prepares block
             prepareContext.duration = 0;
             if (transition.prepares) {
@@ -274,11 +291,14 @@ const int64_t SDWebImageProgressUnitCountUnknown = 1LL;
             }
         } completionHandler:^{
             [NSAnimationContext runAnimationGroup:^(NSAnimationContext * _Nonnull context) {
+                if (!view.sd_latestOperationKey) {
+                    return;
+                }
                 context.duration = transition.duration;
-                #pragma clang diagnostic push
-                #pragma clang diagnostic ignored "-Wdeprecated-declarations"
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
                 CAMediaTimingFunction *timingFunction = transition.timingFunction;
-                #pragma clang diagnostic pop
+#pragma clang diagnostic pop
                 if (!timingFunction) {
                     timingFunction = SDTimingFunctionFromAnimationOptions(transition.animationOptions);
                 }
@@ -295,6 +315,9 @@ const int64_t SDWebImageProgressUnitCountUnknown = 1LL;
                     transition.animations(view, image);
                 }
             } completionHandler:^{
+                if (!view.sd_latestOperationKey) {
+                    return;
+                }
                 if (transition.completion) {
                     transition.completion(YES);
                 }

Tests/Tests/SDWebCacheCategoriesTests.m

@@ -208,6 +208,7 @@
     [imageView sd_internalSetImageWithURL:originalImageURL placeholderImage:nil options:0 context:nil setImageBlock:nil progress:nil completed:nil];
     [imageView sd_cancelCurrentImageLoad];
     NSString *operationKey = NSStringFromClass(UIView.class);
+    expect(imageView.sd_latestOperationKey).beNil();
     expect([imageView sd_imageLoadOperationForKey:operationKey]).beNil();
 }