Add some defensive cleanup of cancelBlock in RCTImageLoader

Reviewed By: mmmulani

Differential Revision: D3742177

fbshipit-source-id: 1cd16c2519052ec5811ecadf2530a5846b4ae1bc

Libraries/Image/RCTImageLoader.m

@@ -294,10 +294,6 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
                                                     progressBlock:(RCTImageLoaderProgressBlock)progressHandler
                                                   completionBlock:(void (^)(NSError *error, id imageOrData, BOOL cacheResult, NSString *fetchDate))completionBlock
 {
-  __block volatile uint32_t cancelled = 0;
-  __block dispatch_block_t cancelLoad = nil;
-  __weak RCTImageLoader *weakSelf = self;
-
   {
     NSMutableURLRequest *mutableRequest = [request mutableCopy];
     [NSURLProtocol setProperty:@"RCTImageLoader"
@@ -316,9 +312,14 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
   BOOL requiresScheduling = [loadHandler respondsToSelector:@selector(requiresScheduling)] ?
       [loadHandler requiresScheduling] : YES;
 
+  __block volatile uint32_t cancelled = 0;
+  __block dispatch_block_t cancelLoad = nil;
   void (^completionHandler)(NSError *, id, NSString *) = ^(NSError *error, id imageOrData, NSString *fetchDate) {
+    cancelLoad = nil;
+
     BOOL cacheResult = [loadHandler respondsToSelector:@selector(shouldCacheLoadedImages)] ?
       [loadHandler shouldCacheLoadedImages] : YES;
+
     // If we've received an image, we should try to set it synchronously,
     // if it's data, do decoding on a background thread.
     if (RCTIsMainQueue() && ![imageOrData isKindOfClass:[UIImage class]]) {
@@ -352,6 +353,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
     [self setUp];
   }
 
+  __weak RCTImageLoader *weakSelf = self;
   dispatch_async(_URLRequestQueue, ^{
     __typeof(self) strongSelf = weakSelf;
     if (cancelled || !strongSelf) {
@@ -364,7 +366,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
                                           scale:scale
                                      resizeMode:resizeMode
                                 progressHandler:progressHandler
-                              completionHandler:^(NSError *error, UIImage *image){
+                              completionHandler:^(NSError *error, UIImage *image) {
                                 completionHandler(error, image, nil);
                               }];
     } else {
@@ -378,6 +380,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
   return ^{
     if (cancelLoad) {
       cancelLoad();
+      cancelLoad = nil;
     }
     OSAtomicOr32Barrier(1, &cancelled);
   };
@@ -464,7 +467,6 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
       // Prepare for next task
       [strongSelf dequeueTasks];
     });
-
   }];
 
   task.downloadProgressBlock = progressHandler;
@@ -488,13 +490,19 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
                                                      scale:(CGFloat)scale
                                                    clipped:(BOOL)clipped
                                                 resizeMode:(RCTResizeMode)resizeMode
-                                             progressBlock:(RCTImageLoaderProgressBlock)progressHandler
+                                             progressBlock:(RCTImageLoaderProgressBlock)progressBlock
                                            completionBlock:(RCTImageLoaderCompletionBlock)completionBlock
 {
   __block volatile uint32_t cancelled = 0;
-  __block void(^cancelLoad)(void) = nil;
+  __block dispatch_block_t cancelLoad = nil;
-  __weak RCTImageLoader *weakSelf = self;
+  dispatch_block_t cancellationBlock = ^{
+    if (cancelLoad) {
+      cancelLoad();
+    }
+    OSAtomicOr32Barrier(1, &cancelled);
+  };
 
+  __weak RCTImageLoader *weakSelf = self;
   void (^completionHandler)(NSError *, id, BOOL, NSString *) = ^(NSError *error, id imageOrData, BOOL cacheResult, NSString *fetchDate) {
     __typeof(self) strongSelf = weakSelf;
     if (cancelled || !strongSelf) {
@@ -502,6 +510,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
     }
 
     if (!imageOrData || [imageOrData isKindOfClass:[UIImage class]]) {
+      cancelLoad = nil;
       completionBlock(error, imageOrData);
       return;
     }
@@ -509,27 +518,29 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
     // Check decoded image cache
     if (cacheResult) {
       UIImage *image = [[strongSelf imageCache] imageForUrl:imageURLRequest.URL.absoluteString
-                                                          size:size
+                                                       size:size
-                                                         scale:scale
+                                                      scale:scale
-                                                    resizeMode:resizeMode
+                                                 resizeMode:resizeMode
-                                                  responseDate:fetchDate];
+                                               responseDate:fetchDate];
       if (image) {
+        cancelLoad = nil;
         completionBlock(nil, image);
         return;
       }
     }
 
-    // Store decoded image in cache
+    RCTImageLoaderCompletionBlock decodeCompletionHandler = ^(NSError *error_, UIImage *image) {
-    RCTImageLoaderCompletionBlock cacheResultHandler = ^(NSError *error_, UIImage *image) {
+      if (cacheResult && image) {
-      if (image) {
+        // Store decoded image in cache
         [[strongSelf imageCache] addImageToCache:image
-                                                URL:imageURLRequest.URL.absoluteString
+                                             URL:imageURLRequest.URL.absoluteString
-                                               size:size
+                                            size:size
-                                              scale:scale
+                                           scale:scale
-                                         resizeMode:resizeMode
+                                      resizeMode:resizeMode
-                                       responseDate:fetchDate];
+                                    responseDate:fetchDate];
       }
 
+      cancelLoad = nil;
       completionBlock(error_, image);
     };
 
@@ -538,21 +549,16 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
                                      scale:scale
                                    clipped:clipped
                                 resizeMode:resizeMode
-                           completionBlock:cacheResult ? cacheResultHandler: completionBlock];
+                           completionBlock:decodeCompletionHandler];
   };
 
   cancelLoad = [self _loadImageOrDataWithURLRequest:imageURLRequest
                                                size:size
                                               scale:scale
                                          resizeMode:resizeMode
-                                      progressBlock:progressHandler
+                                      progressBlock:progressBlock
                                     completionBlock:completionHandler];
-  return ^{
+  return cancellationBlock;
-    if (cancelLoad) {
-      cancelLoad();
-    }
-    OSAtomicOr32Barrier(1, &cancelled);
-  };
 }
 
 - (RCTImageLoaderCancellationBlock)decodeImageData:(NSData *)data

Libraries/Image/RCTImageView.m

@@ -273,8 +273,11 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
     }
 
     RCTImageSource *source = _imageSource;
-    CGFloat blurRadius = _blurRadius;
     __weak RCTImageView *weakSelf = self;
+    RCTImageLoaderCompletionBlock completionHandler = ^(NSError *error, UIImage *loadedImage) {
+      [weakSelf imageLoaderLoadedImage:loadedImage error:error forImageSource:source];
+    };
+
     _reloadImageCancellationBlock =
     [_bridge.imageLoader loadImageWithURLRequest:source.request
                                             size:imageSize
@@ -282,57 +285,64 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
                                          clipped:NO
                                       resizeMode:_resizeMode
                                    progressBlock:progressHandler
-                                 completionBlock:^(NSError *error, UIImage *loadedImage) {
+                                 completionBlock:completionHandler];
-
-      RCTImageView *strongSelf = weakSelf;
-      void (^setImageBlock)(UIImage *) = ^(UIImage *image) {
-        if (![source isEqual:strongSelf.imageSource]) {
-          // Bail out if source has changed since we started loading
-          return;
-        }
-        if (image.reactKeyframeAnimation) {
-          [strongSelf.layer addAnimation:image.reactKeyframeAnimation forKey:@"contents"];
-        } else {
-          [strongSelf.layer removeAnimationForKey:@"contents"];
-          strongSelf.image = image;
-        }
-        if (error) {
-          if (strongSelf->_onError) {
-            strongSelf->_onError(@{ @"error": error.localizedDescription });
-          }
-        } else {
-          if (strongSelf->_onLoad) {
-            strongSelf->_onLoad(nil);
-          }
-        }
-        if (strongSelf->_onLoadEnd) {
-          strongSelf->_onLoadEnd(nil);
-        }
-      };
-
-      if (blurRadius > __FLT_EPSILON__) {
-        // Blur on a background thread to avoid blocking interaction
-        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
-          UIImage *image = RCTBlurredImageWithRadius(loadedImage, blurRadius);
-          RCTExecuteOnMainQueue(^{
-            setImageBlock(image);
-          });
-        });
-      } else {
-        // No blur, so try to set the image on the main thread synchronously to minimize image
-        // flashing. (For instance, if this view gets attached to a window, then -didMoveToWindow
-        // calls -reloadImage, and we want to set the image synchronously if possible so that the
-        // image property is set in the same CATransaction that attaches this view to the window.)
-        RCTExecuteOnMainQueue(^{
-          setImageBlock(loadedImage);
-        });
-      }
-    }];
   } else {
     [self clearImage];
   }
 }
 
+- (void)imageLoaderLoadedImage:(UIImage *)loadedImage error:(NSError *)error forImageSource:(RCTImageSource *)source
+{
+  if (![source isEqual:_imageSource]) {
+    // Bail out if source has changed since we started loading
+    return;
+  }
+
+  if (error) {
+    if (_onError) {
+      _onError(@{ @"error": error.localizedDescription });
+    }
+    if (_onLoadEnd) {
+      _onLoadEnd(nil);
+    }
+    return;
+  }
+
+  void (^setImageBlock)(UIImage *) = ^(UIImage *image) {
+    if (image.reactKeyframeAnimation) {
+      [self.layer addAnimation:image.reactKeyframeAnimation forKey:@"contents"];
+    } else {
+      [self.layer removeAnimationForKey:@"contents"];
+      self.image = image;
+    }
+
+    if (self->_onLoad) {
+      self->_onLoad(nil);
+    }
+    if (self->_onLoadEnd) {
+      self->_onLoadEnd(nil);
+    }
+  };
+
+  if (_blurRadius > __FLT_EPSILON__) {
+    // Blur on a background thread to avoid blocking interaction
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+      UIImage *blurredImage = RCTBlurredImageWithRadius(loadedImage, self->_blurRadius);
+      RCTExecuteOnMainQueue(^{
+        setImageBlock(blurredImage);
+      });
+    });
+  } else {
+    // No blur, so try to set the image on the main thread synchronously to minimize image
+    // flashing. (For instance, if this view gets attached to a window, then -didMoveToWindow
+    // calls -reloadImage, and we want to set the image synchronously if possible so that the
+    // image property is set in the same CATransaction that attaches this view to the window.)
+    RCTExecuteOnMainQueue(^{
+      setImageBlock(loadedImage);
+    });
+  }
+}
+
 - (void)reactSetFrame:(CGRect)frame
 {
   [super reactSetFrame:frame];

Libraries/Image/RCTImageViewManager.m

@@ -49,13 +49,13 @@ RCT_EXPORT_METHOD(getSize:(NSURLRequest *)request
                   errorBlock:(RCTResponseErrorBlock)errorBlock)
 {
   [self.bridge.imageLoader getImageSizeForURLRequest:request
-                                  block:^(NSError *error, CGSize size) {
+                                               block:^(NSError *error, CGSize size) {
-                                    if (error) {
+                                                 if (error) {
-                                      errorBlock(error);
+                                                   errorBlock(error);
-                                    } else {
+                                                 } else {
-                                      successBlock(@[@(size.width), @(size.height)]);
+                                                   successBlock(@[@(size.width), @(size.height)]);
-                                    }
+                                                 }
-                                  }];
+                                               }];
 }
 
 RCT_EXPORT_METHOD(prefetchImage:(NSURLRequest *)request

Libraries/Network/RCTNetworkTask.m

@@ -78,9 +78,9 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 - (void)cancel
 {
   _status = RCTNetworkTaskFinished;
-  __strong id strongToken = _requestToken;
+  id token = _requestToken;
-  if (strongToken && [_handler respondsToSelector:@selector(cancelRequest:)]) {
+  if (token && [_handler respondsToSelector:@selector(cancelRequest:)]) {
-    [_handler cancelRequest:strongToken];
+    [_handler cancelRequest:token];
   }
   [self invalidate];
 }