Decoupling initialisation and synchronous execution.

Reviewed By: javache

Differential Revision: D4117471

fbshipit-source-id: b00de532c99f041ebba8b9d74972a36827a1a3f4

React/Executors/RCTJSCExecutor.h

@@ -87,15 +87,21 @@ RCT_EXTERN NSString *const RCTFBJSValueClassKey;
 /**
  * @experimental
  * Pass a RCTJSContextProvider object to use an NSThread/JSContext pair that have already been created.
- * The returned executor has already executed the supplied application script synchronously.
+ * The underlying JSContext will be returned in the JSContext pointer if it is non-NULL.
- * The underlying JSContext will be returned in the JSContext pointer if it is non-NULL and there was no error.
- * If an error occurs, this method will return nil and specify the error in the error pointer if it is non-NULL.
  */
 + (instancetype)initializedExecutorWithContextProvider:(RCTJSContextProvider *)JSContextProvider
-                                     applicationScript:(NSData *)applicationScript
+                                             JSContext:(JSContext **)JSContext;
-                                             sourceURL:(NSURL *)sourceURL
+
-                                             JSContext:(JSContext **)JSContext
+/**
-                                                 error:(NSError **)error;
+ * @experimental
+ * synchronouslyExecuteApplicationScript:sourceURL:JSContext:error:
+ *
+ * Run the provided JS Script/Bundle, blocking the caller until it finishes.
+ * If there is an error during execution, it is returned, otherwise `NULL` is
+ * returned.
+ */
+- (NSError *)synchronouslyExecuteApplicationScript:(NSData *)script
+                                         sourceURL:(NSURL *)sourceURL;
 
 /**
  * Invokes the given module/method directly. The completion block will be called with the

React/Executors/RCTJSCExecutor.mm

@@ -252,20 +252,13 @@ static NSThread *newJavaScriptThread(void)
 }
 
 + (instancetype)initializedExecutorWithContextProvider:(RCTJSContextProvider *)JSContextProvider
-                                     applicationScript:(NSData *)applicationScript
-                                             sourceURL:(NSURL *)sourceURL
                                              JSContext:(JSContext **)JSContext
-                                                 error:(NSError **)error
 {
   const RCTJSContextData data = JSContextProvider.data;
   if (JSContext) {
     *JSContext = data.context;
   }
-  RCTJSCExecutor *executor = [[RCTJSCExecutor alloc] initWithJSContextData:data];
+  return [[RCTJSCExecutor alloc] initWithJSContextData:data];
-  if (applicationScript && ![executor _synchronouslyExecuteApplicationScript:applicationScript sourceURL:sourceURL JSContext:data.context error:error]) {
-    return nil; // error has been set by _synchronouslyExecuteApplicationScript:
-  }
-  return executor;
 }
 
 - (instancetype)initWithJSContextData:(const RCTJSContextData &)data
@@ -280,33 +273,29 @@ static NSThread *newJavaScriptThread(void)
   return self;
 }
 
-- (BOOL)_synchronouslyExecuteApplicationScript:(NSData *)script
+- (NSError *)synchronouslyExecuteApplicationScript:(NSData *)script
-                                     sourceURL:(NSURL *)sourceURL
+                                         sourceURL:(NSURL *)sourceURL
-                                     JSContext:(JSContext *)context
-                                         error:(NSError **)error
 {
-  TaggedScript taggedScript = loadTaggedScript(script, sourceURL, _performanceLogger, _randomAccessBundle, error);
+  NSError *loadError;
+  TaggedScript taggedScript = loadTaggedScript(script, sourceURL, _performanceLogger, _randomAccessBundle, &loadError);
 
-  if (!taggedScript.script) {
+  if (loadError) {
-    return NO;
+    return loadError;
   }
 
   if (taggedScript.tag == RCTScriptRAMBundle) {
-    registerNativeRequire(context, self);
+    registerNativeRequire(_context.context, self);
   }
 
-  NSError *returnedError = executeApplicationScript(taggedScript, sourceURL,
+  NSError *execError = executeApplicationScript(taggedScript, sourceURL,
-                                                    _jscWrapper,
+                                                _jscWrapper,
-                                                    _performanceLogger,
+                                                _performanceLogger,
-                                                    _context.context.JSGlobalContextRef);
+                                                _context.context.JSGlobalContextRef);
-  if (returnedError) {
+  if (execError) {
-    if (error) {
+    return execError;
-      *error = returnedError;
-    }
-    return NO;
-  } else {
-    return YES;
   }
+
+  return NULL;
 }
 
 - (RCTJavaScriptContext *)context