BC Kill-switch

Reviewed By: javache

Differential Revision: D4159923

fbshipit-source-id: 9814c76d04f7230fda7693efac3f6623cc882ccf

React/Executors/RCTJSCExecutor.h

@@ -51,13 +51,19 @@ RCT_EXTERN NSString *const RCTFBJSValueClassKey;
  */
 @interface RCTJSContextProvider : NSObject
 
-- (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary;
+- (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary
+                                tryBytecode:(BOOL)tryBytecode;
 
 /**
  * Marks whether the provider uses the custom implementation of JSC and not the system one.
  */
 @property (nonatomic, readonly, assign) BOOL useCustomJSCLibrary;
 
+/**
+ * Marks whether it is safe to try and run bytecode if given the choice.
+ */
+@property (nonatomic, readonly) BOOL tryBytecode;
+
 @end
 
 /**
@@ -89,6 +95,15 @@ RCT_EXTERN NSString *const RCTFBJSValueClassKey;
  */
 - (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary;
 
+/**
+ * @experimental
+ * Inits a new executor instance with given configuration flags. Please refer to
+ * the documentation for `RCTJSContextProvider` for more information as to their
+ * purpose.
+ */
+- (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary
+                                tryBytecode:(BOOL)tryBytecode;
+
 /**
  * @experimental
  * Pass a RCTJSContextProvider object to use an NSThread/JSContext pair that have already been created.

React/Executors/RCTJSCExecutor.mm

@@ -83,6 +83,7 @@ struct TaggedScript {
 
 struct RCTJSContextData {
   BOOL useCustomJSCLibrary;
+  BOOL tryBytecode;
   NSThread *javaScriptThread;
   JSContext *context;
   RCTJSCWrapper *jscWrapper;
@@ -154,6 +155,7 @@ RCT_NOT_IMPLEMENTED(-(instancetype)init)
 {
   // Set at init time:
   BOOL _useCustomJSCLibrary;
+  BOOL _tryBytecode;
   NSThread *_javaScriptThread;
 
   // Set at setUp time:
@@ -238,11 +240,19 @@ static NSThread *newJavaScriptThread(void)
 }
 
 - (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary
+{
+  return [self initWithUseCustomJSCLibrary:useCustomJSCLibrary
+                               tryBytecode:NO];
+}
+
+- (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary
+                                tryBytecode:(BOOL)tryBytecode
 {
   RCT_PROFILE_BEGIN_EVENT(0, @"-[RCTJSCExecutor init]", nil);
 
   if (self = [super init]) {
     _useCustomJSCLibrary = useCustomJSCLibrary;
+    _tryBytecode = tryBytecode;
     _valid = YES;
     _javaScriptThread = newJavaScriptThread();
   }
@@ -265,6 +275,7 @@ static NSThread *newJavaScriptThread(void)
 {
   if (self = [super init]) {
     _useCustomJSCLibrary = data.useCustomJSCLibrary;
+    _tryBytecode = data.tryBytecode;
     _valid = YES;
     _javaScriptThread = data.javaScriptThread;
     _jscWrapper = data.jscWrapper;
@@ -502,7 +513,9 @@ static void installBasicSynchronousHooksOnContext(JSContext *context)
 
 - (int32_t)bytecodeFileFormatVersion
 {
-  return _jscWrapper->JSBytecodeFileFormatVersion;
+  return _tryBytecode
+    ? _jscWrapper->JSBytecodeFileFormatVersion
+    : JSNoBytecodeFileFormatVersion;
 }
 
 - (NSString *)contextName
@@ -978,10 +991,12 @@ static NSData *loadRAMBundle(NSURL *sourceURL, NSError **error, RandomAccessBund
 }
 
 - (instancetype)initWithUseCustomJSCLibrary:(BOOL)useCustomJSCLibrary
+                                tryBytecode:(BOOL)tryBytecode
 {
   if (self = [super init]) {
     _semaphore = dispatch_semaphore_create(0);
     _useCustomJSCLibrary = useCustomJSCLibrary;
+    _tryBytecode = tryBytecode;
     _javaScriptThread = newJavaScriptThread();
     [self performSelector:@selector(_createContext) onThread:_javaScriptThread withObject:nil waitUntilDone:NO];
   }
@@ -1003,6 +1018,7 @@ static NSData *loadRAMBundle(NSURL *sourceURL, NSError **error, RandomAccessBund
   dispatch_semaphore_wait(_semaphore, DISPATCH_TIME_FOREVER);
   return {
     .useCustomJSCLibrary = _useCustomJSCLibrary,
+    .tryBytecode = _tryBytecode,
     .javaScriptThread = _javaScriptThread,
     .context = _context,
     .jscWrapper = _jscWrapper,