Add and use reloadWithReason to iOS

Summary:
This diff adds a new reloading method reloadWithReason that allows callers to provide a reason for why a reload was requested.

This reason is useful for understanding why users are reloading, and why Fast Refresh is bailing out to a full reload. I also updated the places we reload with the reasons listed below.

**Standard native reasons:**
- Redbox
- Command
- Global hotkey
- Profiling controls
- Dev menu - reload
- Dev menu - reset to default
- Dev menu - apply changes

**From JavaScript (added in a later diff):**
- Fast Refresh - Unrecoverable
- Fast Refresh - No root boundary
- Fast Refresh - Invalidated boundary
- Fast Refresh - Invalidated root boundary

**Misc reasons and fallback for when a reason is unavailable:**
- Unknown from JS
- Uncategorized from JS
- Unknown from bridge
- Unknown from cxx bridge
- Requested from bridge
- Custom executor class reset

Reviewed By: cpojer

Differential Revision: D17499339

fbshipit-source-id: 12a21ffa05708c9b921d93911f190cdffc5c78d5

React/Base/RCTBridge.h

@@ -254,12 +254,17 @@ RCT_EXTERN void RCTEnableTurboModule(BOOL enabled);
 /**
  * Reload the bundle and reset executor & modules. Safe to call from any thread.
  */
-- (void)reload;
+- (void)reload __deprecated_msg("Call reloadWithReason instead");
+
+/**
+ * Reload the bundle and reset executor & modules. Safe to call from any thread.
+ */
+- (void)reloadWithReason:(NSString *)reason;
 
 /**
  * Inform the bridge, and anything subscribing to it, that it should reload.
  */
-- (void)requestReload __deprecated_msg("Call reload instead");
+- (void)requestReload __deprecated_msg("Call reloadWithReason instead");
 
 /**
  * Says whether bridge has started receiving calls from javascript.

React/Base/RCTBridge.m

@@ -244,7 +244,7 @@ - (void)setRCTTurboModuleLookupDelegate:(id<RCTTurboModuleLookupDelegate>)turboM
 
 - (void)didReceiveReloadCommand
 {
-  [self reload];
+  [self reloadWithReason:@"Command"];
 }
 
 - (NSArray<Class> *)moduleClasses
@@ -290,14 +290,22 @@ - (BOOL)moduleIsInitialized:(Class)moduleClass
   return [self.batchedBridge moduleIsInitialized:moduleClass];
 }
 
+/**
+ * Legacy reload, please use reloadWithReason and provide a reason for stats.
+ */
 - (void)reload
+{
+   [self reloadWithReason:@"Unknown from bridge"];
+}
+
+- (void)reloadWithReason:(NSString *)reason
 {
   #if RCT_ENABLE_INSPECTOR && !TARGET_OS_UIKITFORMAC
   // Disable debugger to resume the JsVM & avoid thread locks while reloading
   [RCTInspectorDevServerHelper disableDebugger];
   #endif
 
-  [[NSNotificationCenter defaultCenter] postNotificationName:RCTBridgeWillReloadNotification object:self];
+  [[NSNotificationCenter defaultCenter] postNotificationName:RCTBridgeWillReloadNotification object:self userInfo:@{@"reason": reason} ];
 
   /**
    * Any thread
@@ -314,7 +322,7 @@ - (void)reload
 
 - (void)requestReload
 {
-  [self reload];
+  [self reloadWithReason:@"Requested from bridge"];
 }
 
 - (Class)bridgeClass

React/CxxBridge/RCTCxxBridge.mm

@@ -487,7 +487,7 @@ - (id)moduleForName:(NSString *)moduleName lazilyLoadIfNecessary:(BOOL)lazilyLoa
     }
     return moduleData.instance;
   }
-  
+
   static NSSet<NSString *> *ignoredModuleLoadFailures = [NSSet setWithArray: @[@"UIManager"]];
 
   // Module may not be loaded yet, so attempt to force load it here.
@@ -1009,7 +1009,15 @@ - (void)reload
   if (!_valid) {
     RCTLogWarn(@"Attempting to reload bridge before it's valid: %@. Try restarting the development server if connected.", self);
   }
-  [_parentBridge reload];
+  [_parentBridge reloadWithReason:@"Unknown from cxx bridge"];
+}
+
+- (void)reloadWithReason:(NSString *)reason
+{
+  if (!_valid) {
+    RCTLogWarn(@"Attempting to reload bridge before it's valid: %@. Try restarting the development server if connected.", self);
+  }
+  [_parentBridge reloadWithReason:reason];
 }
 
 - (Class)executorClass

React/DevSupport/RCTDevMenu.m

@@ -200,7 +200,7 @@ - (void)setDefaultJSBundle
   [[RCTBundleURLProvider sharedSettings] resetToDefaults];
   self->_bridge.bundleURL = [[RCTBundleURLProvider sharedSettings] jsBundleURLForFallbackResource:nil
                                                                                 fallbackExtension:nil];
-  [self->_bridge reload];
+  [self->_bridge reloadWithReason:@"Dev menu - reset to default"];
 }
 
 - (NSArray<RCTDevMenuItem *> *)_menuItemsToPresent
@@ -214,7 +214,7 @@ - (void)setDefaultJSBundle
 
   [items addObject:[RCTDevMenuItem buttonItemWithTitle:@"Reload"
                                                handler:^{
-                                                 [bridge reload];
+                                                 [bridge reloadWithReason:@"Dev menu - reload"];
                                                }]];
 
   if (!devSettings.isProfilingEnabled) {
@@ -373,7 +373,7 @@ - (void)setDefaultJSBundle
                                                                       fallbackResource:nil]
                                                         : [strongBridge.delegate sourceURLForBridge:strongBridge];
                                                     strongBridge.bundleURL = bundleURL;
-                                                    [strongBridge reload];
+                                                    [strongBridge reloadWithReason:@"Dev menu - apply changes"];
                                                   }
                                                 }]];
                       [alertController addAction:[UIAlertAction actionWithTitle:@"Reset to Default"
@@ -455,7 +455,7 @@ - (BOOL)shakeToShow
 RCT_EXPORT_METHOD(reload)
 {
   WARN_DEPRECATED_DEV_MENU_EXPORT();
-  [_bridge reload];
+    [_bridge reloadWithReason:@"Unknown from JS"];
 }
 
 RCT_EXPORT_METHOD(debugRemotely : (BOOL)enableDebug)

React/Modules/RCTDevSettings.mm

@@ -161,7 +161,7 @@ - (void)setBridge:(RCTBridge *)bridge
         if (params != (id)kCFNull && [params[@"debug"] boolValue]) {
           weakBridge.executorClass = objc_lookUpClass("RCTWebSocketExecutor");
         }
-        [weakBridge reload];
+        [weakBridge reloadWithReason:@"Global hotkey"];
       }
                        queue:dispatch_get_main_queue()
                    forMethod:@"reload"];
@@ -236,7 +236,13 @@ - (BOOL)isHotLoadingAvailable
 
 RCT_EXPORT_METHOD(reload)
 {
-  [self.bridge reload];
+  [self.bridge reloadWithReason:@"Unknown From JS"];
+}
+
+RCT_EXPORT_METHOD(reloadWithReason : (NSString *) reason)
+{
+  [self.bridge reloadWithReason:reason];
+
 }
 
 RCT_EXPORT_METHOD(setIsShakeToShowDevMenuEnabled : (BOOL)enabled)
@@ -369,7 +375,7 @@ - (void)setExecutorClass:(Class)executorClass
     }
 
     self.bridge.executorClass = executorClass;
-    [self.bridge reload];
+    [self.bridge reloadWithReason:@"Custom executor class reset"];
   }
 }
 
@@ -442,6 +448,9 @@ - (id)settingForKey:(NSString *)key
 - (void)reload
 {
 }
+- (void)reloadWithReason
+{
+}
 - (void)toggleElementInspector
 {
 }

React/Modules/RCTRedBox.m

@@ -607,7 +607,7 @@ - (void)reloadFromRedBoxWindow:(__unused RCTRedBoxWindow *)redBoxWindow
     if (_overrideReloadAction) {
         _overrideReloadAction();
     } else {
-        [_bridge reload];
+        [_bridge reloadWithReason:@"Redbox"];
     }
     [self dismiss];
 }

React/Profiler/RCTProfile.m

@@ -372,7 +372,7 @@ + (void)vsync:(CADisplayLink *)displayLink
 
 + (void)reload
 {
-  [RCTProfilingBridge() reload];
+  [RCTProfilingBridge() reloadWithReason:@"Profiling controls"];
 }
 
 + (void)toggle:(UIButton *)target