Base class for all object private data passed to JSC

Reviewed By: amnn

Differential Revision: D5761937

fbshipit-source-id: de88cf8b959fc855c3c0786f817bb6032491c819

ReactAndroid/src/main/jni/react/jni/Android.mk

@@ -35,12 +35,13 @@ LOCAL_CFLAGS += $(CXX11_FLAGS)
 LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
 
 LOCAL_LDLIBS += -landroid
-LOCAL_SHARED_LIBRARIES := libfolly_json libfbjni libjsc libglog_init libyoga
+LOCAL_SHARED_LIBRARIES := libfolly_json libfbjni libjsc libglog_init libyoga libprivatedata
 LOCAL_STATIC_LIBRARIES := libreactnative
 
 include $(BUILD_SHARED_LIBRARY)
 
 $(call import-module,cxxreact)
+$(call import-module,privatedata)
 $(call import-module,fb)
 $(call import-module,fbgloginit)
 $(call import-module,folly)

ReactCommon/cxxreact/Android.mk

@@ -44,3 +44,4 @@ $(call import-module,folly)
 $(call import-module,jsc)
 $(call import-module,glog)
 $(call import-module,jschelpers)
+$(call import-module,privatedata)

ReactCommon/cxxreact/JSCExecutor.h

@@ -14,6 +14,7 @@
 #include <jschelpers/JSCHelpers.h>
 #include <jschelpers/JavaScriptCore.h>
 #include <jschelpers/Value.h>
+#include <privatedata/PrivateDataBase.h>
 
 #ifndef RN_EXPORT
 #define RN_EXPORT __attribute__((visibility("default")))
@@ -50,7 +51,7 @@ struct JSCValueEncoder<folly::dynamic> {
   }
 };
 
-class RN_EXPORT JSCExecutor : public JSExecutor {
+class RN_EXPORT JSCExecutor : public JSExecutor, public PrivateDataBase {
 public:
   /**
    * Must be invoked from thread this Executor will run on.

ReactCommon/jschelpers/Android.mk

@@ -27,3 +27,4 @@ include $(BUILD_STATIC_LIBRARY)
 $(call import-module,folly)
 $(call import-module,jsc)
 $(call import-module,glog)
+$(call import-module,privatedata)

ReactCommon/jschelpers/BUCK

@@ -31,9 +31,13 @@ rn_xplat_cxx_library(
     compiler_flags = [
         "-Wall",
         "-fexceptions",
+        "-frtti",
         "-fvisibility=hidden",
         "-std=c++1y",
     ],
+    exported_deps = [
+        react_native_xplat_target("privatedata:privatedata"),
+    ],
     fbobjc_inherited_buck_flags = STATIC_LIBRARY_IOS_FLAGS,
     force_static = True,
     visibility = [

ReactCommon/jschelpers/JSCHelpers.cpp

@@ -14,6 +14,7 @@
 
 #include "JavaScriptCore.h"
 #include "Value.h"
+#include <privatedata/PrivateDataBase.h>
 
 #if WITH_FBJSCEXTENSIONS
 #undef ASSERT
@@ -31,6 +32,18 @@ namespace react {
 
 namespace {
 
+class JSFunctionPrivateData : public PrivateDataBase {
+ public:
+  explicit JSFunctionPrivateData(JSFunction&& function) : jsFunction_{std::move(function)} {}
+
+  JSFunction& getJSFunction() {
+    return jsFunction_;
+  }
+
+private:
+  JSFunction jsFunction_;
+};
+
 JSValueRef functionCaller(
     JSContextRef ctx,
     JSObjectRef function,
@@ -39,8 +52,9 @@ JSValueRef functionCaller(
     const JSValueRef arguments[],
     JSValueRef* exception) {
   const bool isCustomJSC = isCustomJSCPtr(ctx);
-  auto* f = static_cast<JSFunction*>(JSC_JSObjectGetPrivate(isCustomJSC, function));
-  return (*f)(ctx, thisObject, argumentCount, arguments);
+  auto* privateData = PrivateDataBase::cast<JSFunctionPrivateData>(
+    JSC_JSObjectGetPrivate(isCustomJSC, function));
+  return (privateData->getJSFunction())(ctx, thisObject, argumentCount, arguments);
 }
 
 JSClassRef createFuncClass(JSContextRef ctx) {
@@ -52,13 +66,15 @@ JSClassRef createFuncClass(JSContextRef ctx) {
   const bool isCustomJSC = isCustomJSCPtr(ctx);
   if (isCustomJSC) {
     definition.finalize = [](JSObjectRef object) {
-      auto* function = static_cast<JSFunction*>(JSC_JSObjectGetPrivate(true, object));
-      delete function;
+      auto* privateData = PrivateDataBase::cast<JSFunctionPrivateData>(
+        JSC_JSObjectGetPrivate(true, object));
+      delete privateData;
     };
   } else {
     definition.finalize = [](JSObjectRef object) {
-      auto* function = static_cast<JSFunction*>(JSC_JSObjectGetPrivate(false, object));
-      delete function;
+      auto* privateData = PrivateDataBase::cast<JSFunctionPrivateData>(
+        JSC_JSObjectGetPrivate(false, object));
+      delete privateData;
     };
   }
   definition.callAsFunction = exceptionWrapMethod<&functionCaller>();
@@ -77,8 +93,8 @@ JSObjectRef makeFunction(
   }
 
   // dealloc in kClassDef.finalize
-  JSFunction *functionPtr = new JSFunction(std::move(function));
-  auto functionObject = Object(ctx, JSC_JSObjectMake(ctx, *classRef, functionPtr));
+  JSFunctionPrivateData *functionDataPtr = new JSFunctionPrivateData(std::move(function));
+  auto functionObject = Object(ctx, JSC_JSObjectMake(ctx, *classRef, functionDataPtr));
   functionObject.setProperty("name", Value(ctx, name));
   return functionObject;
 }

ReactCommon/jschelpers/Value.h

@@ -11,6 +11,7 @@
 #include <jschelpers/JavaScriptCore.h>
 #include <jschelpers/Unicode.h>
 #include <jschelpers/noncopyable.h>
+#include <privatedata/PrivateDataBase.h>
 
 #ifndef RN_EXPORT
 #define RN_EXPORT __attribute__((visibility("default")))
@@ -211,10 +212,10 @@ class Object : public noncopyable {
   template<typename ReturnType>
   ReturnType* getPrivate() const {
     const bool isCustomJSC = isCustomJSCPtr(m_context);
-    return static_cast<ReturnType*>(JSC_JSObjectGetPrivate(isCustomJSC, m_obj));
+    return PrivateDataBase::cast<ReturnType>(JSC_JSObjectGetPrivate(isCustomJSC, m_obj));
   }
 
-  void setPrivate(void* data) const {
+  void setPrivate(PrivateDataBase* data) const {
     const bool isCustomJSC = isCustomJSCPtr(m_context);
     JSC_JSObjectSetPrivate(isCustomJSC, m_obj, data);
   }

ReactCommon/privatedata/Android.mk

@@ -0,0 +1,21 @@
+LOCAL_PATH := $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := privatedata
+
+LOCAL_SRC_FILES := \
+  PrivateDataBase.cpp \
+
+LOCAL_C_INCLUDES := $(LOCAL_PATH)/..
+LOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)
+
+LOCAL_CFLAGS := \
+  -DLOG_TAG=\"ReactNative\"
+
+LOCAL_CFLAGS += -Wall -Werror -fexceptions -frtti
+CXX11_FLAGS := -std=c++11
+LOCAL_CFLAGS += $(CXX11_FLAGS)
+LOCAL_EXPORT_CPPFLAGS := $(CXX11_FLAGS)
+
+include $(BUILD_SHARED_LIBRARY)

ReactCommon/privatedata/BUCK

@@ -0,0 +1,23 @@
+include_defs("//ReactCommon/DEFS")
+
+rn_xplat_cxx_library(
+    name = "privatedata",
+    srcs = glob(["**/*.cpp"]),
+    header_namespace = "",
+    exported_headers = subdir_glob(
+        [
+            ("", "**/*.h"),
+        ],
+        prefix = "privatedata",
+    ),
+    compiler_flags = [
+        "-Wall",
+        "-fexceptions",
+        "-frtti",
+        "-fvisibility=hidden",
+        "-std=c++1y",
+    ],
+    visibility = [
+        "PUBLIC",
+    ],
+)

ReactCommon/privatedata/PrivateDataBase.cpp

@@ -0,0 +1,10 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+#include "PrivateDataBase.h"
+
+namespace facebook {
+namespace react {
+
+PrivateDataBase::~PrivateDataBase() {}
+
+} }

ReactCommon/privatedata/PrivateDataBase.h

@@ -0,0 +1,42 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+#pragma once
+
+#include <cassert>
+#include <cstdlib>
+#include <type_traits>
+
+#ifndef RN_EXPORT
+#define RN_EXPORT __attribute__((visibility("default")))
+#endif
+
+namespace facebook {
+namespace react {
+
+// Base class for private data used to implement hybrid JS-native objects. A common root class,
+// rtti and dynamic_cast allow us to do some runtime type checking that makes it possible
+// for multiple hybrid object implementations to co-exist.
+class RN_EXPORT PrivateDataBase {
+ public:
+  virtual ~PrivateDataBase();
+
+  // Casts given void* to PrivateDataBase and performs dynamic_cast to desired type. Returns null on
+  // failure.
+  template <typename T>
+  static typename std::enable_if<std::is_base_of<PrivateDataBase, T>::value, T>::type* tryCast(void* ptr) {
+    return dynamic_cast<T*>(reinterpret_cast<PrivateDataBase*>(ptr));
+  }
+
+  // Like tryCast, but aborts on failure.
+  template <typename T>
+  static typename std::enable_if<std::is_base_of<PrivateDataBase, T>::value, T>::type* cast(void* ptr) {
+    auto result = tryCast<T>(ptr);
+    if (!result) {
+      assert(false && "could not cast to desired type");
+      abort();
+    }
+    return result;
+  }
+};
+
+} }