add notifications for dev reload

Reviewed By: alexeylang

Differential Revision: D5630472

fbshipit-source-id: 1c44a52fddead361b43551384bbfc73e2d89438f

React/Base/RCTBridge.h

@@ -44,6 +44,24 @@ RCT_EXTERN NSString *const RCTJavaScriptDidFailToLoadNotification;
  */
 RCT_EXTERN NSString *const RCTDidInitializeModuleNotification;
 
+/**
+ * This notification fires just before the bridge starts processing a request to
+ * reload.
+ */
+RCT_EXTERN NSString *const RCTBridgeWillReloadNotification;
+
+/**
+ * This notification fires just before the bridge begins downloading a script
+ * from the packager.
+ */
+RCT_EXTERN NSString *const RCTBridgeWillDownloadScriptNotification;
+
+/**
+ * This notification fires just after the bridge finishes downloading a script
+ * from the packager.
+ */
+RCT_EXTERN NSString *const RCTBridgeDidDownloadScriptNotification;
+
 /**
  * This block can be used to instantiate modules that require additional
  * init parameters, or additional configuration prior to being used.

React/Base/RCTBridge.m

@@ -29,6 +29,9 @@
 NSString *const RCTJavaScriptDidLoadNotification = @"RCTJavaScriptDidLoadNotification";
 NSString *const RCTJavaScriptDidFailToLoadNotification = @"RCTJavaScriptDidFailToLoadNotification";
 NSString *const RCTDidInitializeModuleNotification = @"RCTDidInitializeModuleNotification";
+NSString *const RCTBridgeWillReloadNotification = @"RCTBridgeWillReloadNotification";
+NSString *const RCTBridgeWillDownloadScriptNotification = @"RCTBridgeWillDownloadScriptNotification";
+NSString *const RCTBridgeDidDownloadScriptNotification = @"RCTBridgeDidDownloadScriptNotification";
 
 static NSMutableArray<Class> *RCTModuleClasses;
 NSArray<Class> *RCTGetModuleClasses(void)
@@ -260,6 +263,8 @@ - (void)reload
   [RCTInspectorDevServerHelper disableDebugger];
   #endif
 
+  [[NSNotificationCenter defaultCenter] postNotificationName:RCTBridgeWillReloadNotification object:self];
+
   /**
    * Any thread
    */

React/CxxBridge/RCTCxxBridge.mm

@@ -377,6 +377,8 @@ - (void)start
 
 - (void)loadSource:(RCTSourceLoadBlock)_onSourceLoad onProgress:(RCTSourceLoadProgressBlock)onProgress
 {
+  NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
+  [center postNotificationName:RCTBridgeWillDownloadScriptNotification object:_parentBridge];
   [_performanceLogger markStartForTag:RCTPLScriptDownload];
   NSUInteger cookie = RCTProfileBeginAsyncEvent(0, @"JavaScript download", nil);
 
@@ -388,6 +390,8 @@ - (void)loadSource:(RCTSourceLoadBlock)_onSourceLoad onProgress:(RCTSourceLoadPr
     RCTProfileEndAsyncEvent(0, @"native", cookie, @"JavaScript download", @"JS async");
     [performanceLogger markStopForTag:RCTPLScriptDownload];
     [performanceLogger setValue:sourceLength forTag:RCTPLBundleSize];
+    [center postNotificationName:RCTBridgeDidDownloadScriptNotification object:self->_parentBridge];
+
     _onSourceLoad(error, source, sourceLength);
   };