RCTImage: Use C atomics instead of OSAtomic

Summary:
The next in my series of :atom: migrations.
Closes https://github.com/facebook/react-native/pull/15278

Differential Revision: D5526468

Pulled By: javache

fbshipit-source-id: 91511c69bc37a6f1382bcf0b0dd847adf10fd43a

Libraries/Image/RCTImageLoader.m

@@ -7,7 +7,7 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 #import <objc/runtime.h>
 
 #import <ImageIO/ImageIO.h>
@@ -324,7 +324,8 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
     BOOL requiresScheduling = [loadHandler respondsToSelector:@selector(requiresScheduling)] ?
     [loadHandler requiresScheduling] : YES;
 
-    __block volatile uint32_t cancelled = 0;
+    __block atomic_bool cancelled = ATOMIC_VAR_INIT(NO);
+    // TODO: Protect this variable shared between threads.
     __block dispatch_block_t cancelLoad = nil;
     void (^completionHandler)(NSError *, id, NSString *) = ^(NSError *error, id imageOrData, NSString *fetchDate) {
         cancelLoad = nil;
@@ -338,11 +339,11 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
             // Most loaders do not return on the main thread, so caller is probably not
             // expecting it, and may do expensive post-processing in the callback
             dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
-                if (!cancelled) {
+                if (!atomic_load(&cancelled)) {
                     completionBlock(error, imageOrData, cacheResult, fetchDate);
                 }
             });
-        } else if (!cancelled) {
+        } else if (!atomic_load(&cancelled)) {
             completionBlock(error, imageOrData, cacheResult, fetchDate);
         }
     };
@@ -369,7 +370,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
     __weak RCTImageLoader *weakSelf = self;
     dispatch_async(_URLRequestQueue, ^{
         __typeof(self) strongSelf = weakSelf;
-        if (cancelled || !strongSelf) {
+        if (atomic_load(&cancelled) || !strongSelf) {
             return;
         }
 
@@ -392,12 +393,15 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
     });
 
     return ^{
+        BOOL alreadyCancelled = atomic_fetch_or(&cancelled, 1);
+        if (alreadyCancelled) {
+            return;
+        }
         dispatch_block_t cancelLoadLocal = cancelLoad;
         cancelLoad = nil;
-        if (cancelLoadLocal && !cancelled) {
+        if (cancelLoadLocal) {
             cancelLoadLocal();
         }
-        OSAtomicOr32Barrier(1, &cancelled);
     };
 }
 
@@ -524,20 +528,25 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
                                           partialLoadBlock:(RCTImageLoaderPartialLoadBlock)partialLoadBlock
                                            completionBlock:(RCTImageLoaderCompletionBlock)completionBlock
 {
-    __block volatile uint32_t cancelled = 0;
+    __block atomic_bool cancelled = ATOMIC_VAR_INIT(NO);
+    // TODO: Protect this variable shared between threads.
     __block dispatch_block_t cancelLoad = nil;
     dispatch_block_t cancellationBlock = ^{
+        BOOL alreadyCancelled = atomic_fetch_or(&cancelled, 1);
+        if (alreadyCancelled) {
+            return;
+        }
         dispatch_block_t cancelLoadLocal = cancelLoad;
-        if (cancelLoadLocal && !cancelled) {
+        cancelLoad = nil;
+        if (cancelLoadLocal) {
             cancelLoadLocal();
         }
-        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) {
+        if (atomic_load(&cancelled) || !strongSelf) {
             return;
         }
 
@@ -606,17 +615,17 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
         return ^{};
     }
 
-    __block volatile uint32_t cancelled = 0;
+    __block atomic_bool cancelled = ATOMIC_VAR_INIT(NO);
     void (^completionHandler)(NSError *, UIImage *) = ^(NSError *error, UIImage *image) {
         if (RCTIsMainQueue()) {
             // Most loaders do not return on the main thread, so caller is probably not
             // expecting it, and may do expensive post-processing in the callback
             dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
-                if (!cancelled) {
+                if (!atomic_load(&cancelled)) {
                     completionBlock(error, clipped ? RCTResizeImageIfNeeded(image, size, scale, resizeMode) : image);
                 }
             });
-        } else if (!cancelled) {
+        } else if (!atomic_load(&cancelled)) {
             completionBlock(error, clipped ? RCTResizeImageIfNeeded(image, size, scale, resizeMode) : image);
         }
     };
@@ -638,7 +647,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
 
             // Do actual decompression on a concurrent background queue
             dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
-                if (!cancelled) {
+                if (!atomic_load(&cancelled)) {
 
                     // Decompress the image data (this may be CPU and memory intensive)
                     UIImage *image = RCTDecodeImageWithData(data, size, scale, resizeMode);
@@ -695,7 +704,7 @@ static UIImage *RCTResizeImageIfNeeded(UIImage *image,
         });
 
         return ^{
-            OSAtomicOr32Barrier(1, &cancelled);
+            atomic_store(&cancelled, YES);
         };
     }
 }

Libraries/Image/RCTImageStoreManager.m

@@ -9,7 +9,7 @@
 
 #import "RCTImageStoreManager.h"
 
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 #import <ImageIO/ImageIO.h>
 #import <MobileCoreServices/UTType.h>
@@ -137,14 +137,14 @@ RCT_EXPORT_METHOD(addImageFromBase64:(NSString *)base64String
 
 - (id)sendRequest:(NSURLRequest *)request withDelegate:(id<RCTURLRequestDelegate>)delegate
 {
-  __block volatile uint32_t cancelled = 0;
+  __block atomic_bool cancelled = ATOMIC_VAR_INIT(NO);
   void (^cancellationBlock)(void) = ^{
-    OSAtomicOr32Barrier(1, &cancelled);
+    atomic_store(&cancelled, YES);
   };
 
   // Dispatch async to give caller time to cancel the request
   dispatch_async(_methodQueue, ^{
-    if (cancelled) {
+    if (atomic_load(&cancelled)) {
       return;
     }
 

Libraries/Image/RCTLocalAssetImageLoader.m

@@ -9,7 +9,7 @@
 
 #import "RCTLocalAssetImageLoader.h"
 
-#import <libkern/OSAtomic.h>
+#import <stdatomic.h>
 
 #import <React/RCTUtils.h>
 
@@ -44,9 +44,9 @@ RCT_EXPORT_MODULE()
                                  partialLoadHandler:(RCTImageLoaderPartialLoadBlock)partialLoadHandler
                                   completionHandler:(RCTImageLoaderCompletionBlock)completionHandler
 {
-  __block volatile uint32_t cancelled = 0;
+  __block atomic_bool cancelled = ATOMIC_VAR_INIT(NO);
   RCTExecuteOnMainQueue(^{
-    if (cancelled) {
+    if (atomic_load(&cancelled)) {
       return;
     }
 
@@ -64,7 +64,7 @@ RCT_EXPORT_MODULE()
   });
 
   return ^{
-    OSAtomicOr32Barrier(1, &cancelled);
+    atomic_store(&cancelled, YES);
   };
 }