Introduce Module Setup Metric (facebook#23859)

Summary:
The `RCTBridge` contains numerous definitions of notification names, which we can observe in order to get insights into the React Native performance.

The Android implementation is a little different, such that you can listen for any of the [following](https://github.com/facebook/react-native/blob/master/ReactAndroid/src/main/java/com/facebook/react/bridge/ReactMarkerConstants.java) marker constants, simply by including the following code:

```java
ReactMarker.addListener(new ReactMarker.MarkerListener() {
  Override
  public void logMarker(ReactMarkerConstants name, Nullable String tag, int instanceKey) {
    Log.d("ReactNativeEvent", "name: "+ name.name() + " tag: " + tag);
  }
});
```
This will allow you to perform the necessary processing, calculations as required.

 ---

This PR enables observing for the module setup event (`RCTDidSetupModuleNotification`) by including the respective module's name & setup time in milliseconds.

[iOS] [Added] - Gain insights on the module setup times by observing `RCTDidSetupModuleNotification`. The `userInfo` dictionary will contain the module name and setup time in milliseconds. These values can be extracted via `RCTDidSetupModuleNotificationModuleNameKey ` and `RCTDidSetupModuleNotificationSetupTimeKey`.
Pull Request resolved: facebook#23859

Differential Revision: D14579066

Pulled By: PeteTheHeat

fbshipit-source-id: 52645127c3fc6aa5bd73e3bd471fccd79cb05c14

Author: a-dilettante

React/Base/RCTBridge.h

@@ -48,6 +48,25 @@ RCT_EXTERN NSString *const RCTJavaScriptDidFailToLoadNotification;
  */
 RCT_EXTERN NSString *const RCTDidInitializeModuleNotification;
 
+/**
+ * This notification fires each time a native module is setup after it is initialized. The
+ * `RCTDidSetupModuleNotificationModuleNameKey` key will contain a reference to the module name and
+ * `RCTDidSetupModuleNotificationSetupTimeKey` will contain the setup time in ms.
+ */
+RCT_EXTERN NSString *const RCTDidSetupModuleNotification;
+
+/**
+ * Key for the module name (NSString) in the
+ * RCTDidSetupModuleNotification userInfo dictionary.
+ */
+RCT_EXTERN NSString *const RCTDidSetupModuleNotificationModuleNameKey;
+
+/**
+ * Key for the setup time (NSNumber) in the
+ * RCTDidSetupModuleNotification userInfo dictionary.
+ */
+RCT_EXTERN NSString *const RCTDidSetupModuleNotificationSetupTimeKey;
+
 /**
  * This notification fires just before the bridge starts processing a request to
  * reload.

React/Base/RCTBridge.m

@@ -27,6 +27,9 @@
 NSString *const RCTJavaScriptDidLoadNotification = @"RCTJavaScriptDidLoadNotification";
 NSString *const RCTJavaScriptDidFailToLoadNotification = @"RCTJavaScriptDidFailToLoadNotification";
 NSString *const RCTDidInitializeModuleNotification = @"RCTDidInitializeModuleNotification";
+NSString *const RCTDidSetupModuleNotification = @"RCTDidSetupModuleNotification";
+NSString *const RCTDidSetupModuleNotificationModuleNameKey = @"moduleName";
+NSString *const RCTDidSetupModuleNotificationSetupTimeKey = @"setupTime";
 NSString *const RCTBridgeWillReloadNotification = @"RCTBridgeWillReloadNotification";
 NSString *const RCTBridgeWillDownloadScriptNotification = @"RCTBridgeWillDownloadScriptNotification";
 NSString *const RCTBridgeDidDownloadScriptNotification = @"RCTBridgeDidDownloadScriptNotification";

React/Base/RCTPerformanceLogger.h

@@ -20,6 +20,7 @@ typedef NS_ENUM(NSUInteger, RCTPLTag) {
   RCTPLNativeModuleMainThread,
   RCTPLNativeModulePrepareConfig,
   RCTPLNativeModuleMainThreadUsesCount,
+  RCTPLNativeModuleSetup,
   RCTPLJSCWrapperOpenLibrary,
   RCTPLBridgeStartup,
   RCTPLTTI,

React/Base/RCTPerformanceLogger.m

@@ -41,6 +41,7 @@ - (instancetype)init
       @"NativeModulePrepareConfig",
       @"NativeModuleInjectConfig",
       @"NativeModuleMainThreadUsesCount",
+      @"NativeModuleSetup",
       @"JSCWrapperOpenLibrary",
       @"JSCExecutorSetup",
       @"BridgeStartup",

React/CxxBridge/RCTCxxBridge.mm

@@ -99,6 +99,19 @@ static bool isRAMBundle(NSData *script) {
   return parseTypeFromHeader(header) == ScriptTag::RAMBundle;
 }
 
+static void notifyAboutModuleSetup(RCTPerformanceLogger *performanceLogger, const char *tag) {
+  NSString *moduleName = [[NSString alloc] initWithUTF8String:tag];
+  if (moduleName) {
+    int64_t setupTime = [performanceLogger durationForTag:RCTPLNativeModuleSetup];
+    [[NSNotificationCenter defaultCenter] postNotificationName:RCTDidSetupModuleNotification
+                                                        object:nil
+                                                      userInfo:@{
+                                                                 RCTDidSetupModuleNotificationModuleNameKey: moduleName,
+                                                                 RCTDidSetupModuleNotificationSetupTimeKey: @(setupTime)
+                                                                 }];
+  }
+}
+
 static void registerPerformanceLoggerHooks(RCTPerformanceLogger *performanceLogger) {
   __weak RCTPerformanceLogger *weakPerformanceLogger = performanceLogger;
   ReactMarker::logTaggedMarker = [weakPerformanceLogger](const ReactMarker::ReactMarkerId markerId, const char *__unused tag) {
@@ -116,11 +129,16 @@ static void registerPerformanceLoggerHooks(RCTPerformanceLogger *performanceLogg
         [weakPerformanceLogger appendStopForTag:RCTPLRAMNativeRequires];
         [weakPerformanceLogger addValue:1 forTag:RCTPLRAMNativeRequiresCount];
         break;
+      case ReactMarker::NATIVE_MODULE_SETUP_START:
+        [weakPerformanceLogger markStartForTag:RCTPLNativeModuleSetup];
+        break;
+      case ReactMarker::NATIVE_MODULE_SETUP_STOP:
+        [weakPerformanceLogger markStopForTag:RCTPLNativeModuleSetup];
+        notifyAboutModuleSetup(weakPerformanceLogger, tag);
+        break;
       case ReactMarker::CREATE_REACT_CONTEXT_STOP:
       case ReactMarker::JS_BUNDLE_STRING_CONVERT_START:
       case ReactMarker::JS_BUNDLE_STRING_CONVERT_STOP:
-      case ReactMarker::NATIVE_MODULE_SETUP_START:
-      case ReactMarker::NATIVE_MODULE_SETUP_STOP:
       case ReactMarker::REGISTER_JS_SEGMENT_START:
       case ReactMarker::REGISTER_JS_SEGMENT_STOP:
         // These are not used on iOS.