add files changed count to reload metrics

Reviewed By: alexeylang

Differential Revision: D5694813

fbshipit-source-id: 2e2517e60a7547e261a7c15a3a9138dbb3cb9783

React/Base/RCTBridge.h

@@ -62,6 +62,12 @@ RCT_EXTERN NSString *const RCTBridgeWillDownloadScriptNotification;
  */
 RCT_EXTERN NSString *const RCTBridgeDidDownloadScriptNotification;
 
+/**
+ * Key for the RCTSource object in the RCTBridgeDidDownloadScriptNotification
+ * userInfo dictionary.
+ */
+RCT_EXTERN NSString *const RCTBridgeDidDownloadScriptNotificationSourceKey;
+
 /**
  * This block can be used to instantiate modules that require additional
  * init parameters, or additional configuration prior to being used.

React/Base/RCTBridge.m

@@ -32,6 +32,7 @@ NSString *const RCTDidInitializeModuleNotification = @"RCTDidInitializeModuleNot
 NSString *const RCTBridgeWillReloadNotification = @"RCTBridgeWillReloadNotification";
 NSString *const RCTBridgeWillDownloadScriptNotification = @"RCTBridgeWillDownloadScriptNotification";
 NSString *const RCTBridgeDidDownloadScriptNotification = @"RCTBridgeDidDownloadScriptNotification";
+NSString *const RCTBridgeDidDownloadScriptNotificationSourceKey = @"source";
 
 static NSMutableArray<Class> *RCTModuleClasses;
 NSArray<Class> *RCTGetModuleClasses(void)

React/Base/RCTJavaScriptLoader.h

@@ -25,6 +25,11 @@ NS_ENUM(NSInteger) {
   RCTJavaScriptLoaderErrorCannotBeLoadedSynchronously = 1000,
 };
 
+NS_ENUM(NSInteger) {
+  RCTSourceFilesChangedCountNotBuiltByBundler = -2,
+  RCTSourceFilesChangedCountRebuiltFromScratch = -1,
+};
+
 @interface RCTLoadingProgress : NSObject
 
 @property (nonatomic, copy) NSString *status;
@@ -55,6 +60,15 @@ NS_ENUM(NSInteger) {
  */
 @property (nonatomic, readonly) NSUInteger length;
 
+/**
+ * Returns number of files changed when building this bundle:
+ *
+ *  - RCTSourceFilesChangedCountNotBuiltByBundler if the source wasn't built by the bundler (e.g. read from disk)
+ *  - RCTSourceFilesChangedCountRebuiltFromScratch if the source was rebuilt from scratch by the bundler
+ *  - Otherwise, the number of files changed when incrementally rebuilding the source
+ */
+@property (nonatomic, readonly) NSInteger filesChangedCount;
+
 @end
 
 typedef void (^RCTSourceLoadProgressBlock)(RCTLoadingProgress *progressData);

React/Base/RCTJavaScriptLoader.mm

@@ -28,6 +28,7 @@ NSString *const RCTJavaScriptLoaderErrorDomain = @"RCTJavaScriptLoaderErrorDomai
   NSURL *_url;
   NSData *_data;
   NSUInteger _length;
+  NSInteger _filesChangedCount;
 }
 
 @end
@@ -40,6 +41,7 @@ static RCTSource *RCTSourceCreate(NSURL *url, NSData *data, int64_t length) NS_R
   source->_url = url;
   source->_data = data;
   source->_length = length;
+  source->_filesChangedCount = RCTSourceFilesChangedCountNotBuiltByBundler;
   return source;
 }
 
@@ -205,6 +207,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   return [NSData dataWithBytes:&header length:sizeof(header)];
 }
 
+static void parseHeaders(NSDictionary *headers, RCTSource *source) {
+  source->_filesChangedCount = [headers[@"X-Metro-Files-Changed-Count"] integerValue];
+}
+
 static void attemptAsynchronousLoadOfBundleAtURL(NSURL *scriptURL, RCTSourceLoadProgressBlock onProgress, RCTSourceLoadBlock onComplete)
 {
   scriptURL = sanitizeURL(scriptURL);
@@ -282,7 +288,9 @@ static void attemptAsynchronousLoadOfBundleAtURL(NSURL *scriptURL, RCTSourceLoad
       return;
     }
 
-    onComplete(nil, RCTSourceCreate(scriptURL, data, data.length));
+    RCTSource *source = RCTSourceCreate(scriptURL, data, data.length);
+    parseHeaders(headers, source);
+    onComplete(nil, source);
   } progressHandler:^(NSDictionary *headers, NSNumber *loaded, NSNumber *total) {
     // Only care about download progress events for the javascript bundle part.
     if ([headers[@"Content-Type"] isEqualToString:@"application/javascript"]) {

React/CxxBridge/RCTCxxBridge.mm

@@ -390,7 +390,9 @@ struct RCTInstanceCallback : public InstanceCallback {
     RCTProfileEndAsyncEvent(0, @"native", cookie, @"JavaScript download", @"JS async");
     [performanceLogger markStopForTag:RCTPLScriptDownload];
     [performanceLogger setValue:source.length forTag:RCTPLBundleSize];
-    [center postNotificationName:RCTBridgeDidDownloadScriptNotification object:self->_parentBridge];
+
+    NSDictionary *userInfo = source ? @{ RCTBridgeDidDownloadScriptNotificationSourceKey: source } : nil;
+    [center postNotificationName:RCTBridgeDidDownloadScriptNotification object:self->_parentBridge userInfo:userInfo];
 
     _onSourceLoad(error, source);
   };