Add option to start sampling profiler on app launch

Reviewed By: mhorowitz

Differential Revision: D4415989

fbshipit-source-id: 30704c2b618656cb7cc0ccdf87dec315b30b62f3

React/Executors/RCTJSCExecutor.mm

@@ -338,7 +338,9 @@ static NSThread *newJavaScriptThread(void)
       contextRef = context.JSGlobalContextRef;
     } else {
       if (self->_useCustomJSCLibrary) {
-        JSC_configureJSCForIOS(true);
+        JSC_configureJSCForIOS(true, RCTJSONStringify(@{
+          @"StartSamplingProfilerOnInit": @(self->_bridge.devMenu.startSamplingProfilerOnLaunch)
+        }, NULL).UTF8String);
       }
       contextRef = JSC_JSGlobalContextCreateInGroup(self->_useCustomJSCLibrary, nullptr, nullptr);
       context = [JSC_JSContext(contextRef) contextWithJSGlobalContextRef:contextRef];
@@ -1028,7 +1030,7 @@ static NSData *loadRAMBundle(NSURL *sourceURL, NSError **error, RandomAccessBund
 - (void)_createContext
 {
   if (_useCustomJSCLibrary) {
-    JSC_configureJSCForIOS(true);
+    JSC_configureJSCForIOS(true, "{}");
   }
   JSGlobalContextRef ctx = JSC_JSGlobalContextCreateInGroup(_useCustomJSCLibrary, nullptr, nullptr);
   _context = [JSC_JSContext(ctx) contextWithJSGlobalContextRef:ctx];

React/Modules/RCTDevMenu.h

@@ -30,6 +30,11 @@
  */
 @property (nonatomic, assign) BOOL profilingEnabled;
 
+/**
+ * Enables starting of profiling sampler on launch
+ */
+@property (nonatomic, assign) BOOL startSamplingProfilerOnLaunch;
+
 /**
  * Enables automatic polling for JS code changes. Only applicable when
  * running the app from a server.

React/Modules/RCTDevMenu.mm

@@ -212,6 +212,9 @@ RCT_EXPORT_MODULE()
       self->_executorOverride = [self->_defaults objectForKey:@"executor-override"];
     });
 
+    // Same values are read during the bridge starup path
+    _startSamplingProfilerOnLaunch = [_settings[@"startSamplingProfilerOnLaunch"] boolValue];
+
     // Delay setup until after Bridge init
     dispatch_async(dispatch_get_main_queue(), ^{
       [weakSelf updateSettings:self->_settings];
@@ -537,6 +540,8 @@ RCT_EXPORT_MODULE()
   }
 
   // Add toggles for JSC's sampling profiler, if the profiler is enabled
+  // Note: bridge.jsContext is not implemented in the old bridge, so this code is
+  // duplicated in RCTJSCExecutor
   if (JSC_JSSamplingProfilerEnabled(self->_bridge.jsContext.JSGlobalContextRef)) {
     JSContext *context = self->_bridge.jsContext;
     // Allow to toggle the sampling profiler through RN's dev menu
@@ -625,6 +630,12 @@ RCT_EXPORT_METHOD(debugRemotely:(BOOL)enableDebug)
   [self updateSetting:@"shakeToShow" value:@(_shakeToShow)];
 }
 
+- (void)setStartSamplingProfilerOnLaunch:(BOOL)startSamplingProfilerOnLaunch
+{
+  _startSamplingProfilerOnLaunch = startSamplingProfilerOnLaunch;
+  [self updateSetting:@"startSamplingProfilerOnLaunch" value:@(_startSamplingProfilerOnLaunch)];
+}
+
 RCT_EXPORT_METHOD(setProfilingEnabled:(BOOL)enabled)
 {
   _profilingEnabled = enabled;

ReactCommon/cxxreact/JSCExecutor.cpp

@@ -226,7 +226,7 @@ void JSCExecutor::initOnJSVMThread() throw(JSException) {
   #if defined(__APPLE__)
   const bool useCustomJSC = m_jscConfig.getDefault("UseCustomJSC", false).getBool();
   if (useCustomJSC) {
-    JSC_configureJSCForIOS(true);
+    JSC_configureJSCForIOS(true, toJson(m_jscConfig));
   }
   #else
   const bool useCustomJSC = false;

ReactCommon/jschelpers/JSCWrapper.h

@@ -18,10 +18,11 @@
 #if defined(__APPLE__)
 #import <objc/objc.h>
 #import <JavaScriptCore/JSStringRefCF.h>
+#import <string>
 
 // This is used to substitute an alternate JSC implementation for
 // testing. These calls must all be ABI compatible with the standard JSC.
-extern void configureJSCForIOS();
+extern void configureJSCForIOS(std::string); // TODO: replace with folly::dynamic once supported
 extern JSValueRef JSEvaluateBytecodeBundle(JSContextRef, JSObjectRef, int, JSStringRef, JSValueRef*);
 extern bool JSSamplingProfilerEnabled();
 extern void JSStartSamplingProfilingOnMainJSCThread(JSGlobalContextRef);