Add thread affinity and ASSERT() for same-thread restriction to WTF::Function

third_party/WebKit/Source/wtf/Functional.h

Index: third_party/WebKit/Source/wtf/Functional.h
diff --git a/third_party/WebKit/Source/wtf/Functional.h b/third_party/WebKit/Source/wtf/Functional.h
index d254fd900030641338e13a91a556b3ce19dca36a..8d25909680343619cbcd2e7e9455c24c2f93c35c 100644
--- a/third_party/WebKit/Source/wtf/Functional.h
+++ b/third_party/WebKit/Source/wtf/Functional.h
@@ -176,11 +176,16 @@ template<> struct ParamStorageTraits<void*> {
     static void* unwrap(const StorageType& value) { return value; }
 };
 
-template<typename>
+enum FunctionThreadAffinity {
+    CrossThreadAffinity,
+    SameThreadAffinity
+};
+
+template<typename, FunctionThreadAffinity threadAffinity = SameThreadAffinity>
 class Function;
 
-template<typename R, typename... Args>
-class Function<R(Args...)> {
+template<FunctionThreadAffinity threadAffinity, typename R, typename... Args>
+class Function<R(Args...), threadAffinity> {
     USING_FAST_MALLOC(Function);
     WTF_MAKE_NONCOPYABLE(Function);
 public:
@@ -188,13 +193,41 @@ public:
     virtual R operator()(Args... args) = 0;
 protected:
     Function() = default;
+    void checkThread() { }
 };
 
-template <typename BoundParametersTuple, typename FunctionWrapper, typename... UnboundParameters>
+#if ENABLE(ASSERT)
+template<typename R, typename... Args>
+class Function<R(Args...), SameThreadAffinity> {
+    USING_FAST_MALLOC(Function);
+    WTF_MAKE_NONCOPYABLE(Function);
+public:
+    virtual ~Function()
+    {
+        checkThread();
+    }
+    virtual R operator()(Args... args) = 0;
+protected:
+    Function()
+        : m_createdThread(currentThread())
+    {
+    }
+
+    void NEVER_INLINE checkThread()

[kinuko, 2016/03/02 07:30:56]

sorry, why we need this to be noinline?

[hiroshige, 2016/03/03 02:21:07]

This is to make checkThread() to appear in the crash stack trace to make
detection of violation easier.

+    {
+        RELEASE_ASSERT(m_createdThread == currentThread());
+    }
+
+private:
+    ThreadIdentifier m_createdThread;
+};
+#endif
+
+template <FunctionThreadAffinity threadAffinity, typename BoundParametersTuple, typename FunctionWrapper, typename... UnboundParameters>
 class PartBoundFunctionImpl;
 
-template <typename... BoundParameters, typename FunctionWrapper, typename... UnboundParameters>
-class PartBoundFunctionImpl<std::tuple<BoundParameters...>, FunctionWrapper, UnboundParameters...> final : public Function<typename FunctionWrapper::ResultType(UnboundParameters...)> {
+template <FunctionThreadAffinity threadAffinity, typename... BoundParameters, typename FunctionWrapper, typename... UnboundParameters>
+class PartBoundFunctionImpl<threadAffinity, std::tuple<BoundParameters...>, FunctionWrapper, UnboundParameters...> final : public Function<typename FunctionWrapper::ResultType(UnboundParameters...), threadAffinity> {
 public:
     // We would like to use StorageTraits<UnboundParameters>... with StorageTraits defined as below in order to obtain
     // storage traits of UnboundParameters, but unfortunately MSVC can't handle template using declarations correctly.
@@ -221,6 +254,7 @@ private:
     template <std::size_t... boundIndices>
     typename FunctionWrapper::ResultType callInternal(UnboundParameters... unbound, const base::IndexSequence<boundIndices...>&)
     {
+        this->checkThread();
         // Get each element in m_bound, unwrap them, and call the function with the desired arguments.
         return m_functionWrapper(ParamStorageTraits<typename std::decay<BoundParameters>::type>::unwrap(std::get<boundIndices>(m_bound))..., unbound...);
     }
@@ -229,23 +263,31 @@ private:
     std::tuple<typename ParamStorageTraits<typename std::decay<BoundParameters>::type>::StorageType...> m_bound;
 };
 
-template <typename... UnboundParameters, typename FunctionType, typename... BoundParameters>
-PassOwnPtr<Function<typename FunctionWrapper<FunctionType>::ResultType(UnboundParameters...)>> bind(FunctionType function, BoundParameters&&... boundParameters)
+template <FunctionThreadAffinity threadAffinity, typename... UnboundParameters, typename FunctionType, typename... BoundParameters>
+PassOwnPtr<Function<typename FunctionWrapper<FunctionType>::ResultType(UnboundParameters...), threadAffinity>> bindInternal(FunctionType function, BoundParameters&&... boundParameters)
 {
     // Bound parameters' types are wrapped with std::tuple so we can pass two template parameter packs (bound
     // parameters and unbound) to PartBoundFunctionImpl. Note that a tuple of this type isn't actually created;
     // std::tuple<> is just for carrying the bound parameters' types. Any other class template taking a type parameter
     // pack can be used instead of std::tuple. std::tuple is used just because it's most convenient for this purpose.
-    using BoundFunctionType = PartBoundFunctionImpl<std::tuple<BoundParameters&&...>, FunctionWrapper<FunctionType>, UnboundParameters...>;
+    using BoundFunctionType = PartBoundFunctionImpl<threadAffinity, std::tuple<BoundParameters&&...>, FunctionWrapper<FunctionType>, UnboundParameters...>;
     return adoptPtr(new BoundFunctionType(FunctionWrapper<FunctionType>(function), std::forward<BoundParameters>(boundParameters)...));
 }
 
-typedef Function<void()> Closure;
+template <typename... UnboundParameters, typename FunctionType, typename... BoundParameters>
+PassOwnPtr<Function<typename FunctionWrapper<FunctionType>::ResultType(UnboundParameters...), SameThreadAffinity>> bind(FunctionType function, BoundParameters&&... boundParameters)
+{
+    return bindInternal<SameThreadAffinity, UnboundParameters...>(function, std::forward<BoundParameters>(boundParameters)...);
+}
+
+typedef Function<void(), SameThreadAffinity> Closure;
+typedef Function<void(), CrossThreadAffinity> CrossThreadClosure;
 
 } // namespace WTF
 
 using WTF::Function;
 using WTF::bind;
 using WTF::Closure;
+using WTF::CrossThreadClosure;
 
 #endif // WTF_Functional_h