1 // Copyright 2016 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_WASM_MANAGED_H_ 6 #define V8_WASM_MANAGED_H_ 7 8 #include "src/factory.h" 9 #include "src/global-handles.h" 10 #include "src/handles.h" 11 #include "src/isolate.h" 12 13 namespace v8 { 14 namespace internal { 15 // An object that wraps a pointer to a C++ object and manages its lifetime. 16 // The C++ object will be deleted when the managed wrapper object is 17 // garbage collected, or, last resort, if the isolate is torn down before GC, 18 // as part of Isolate::Dispose(). 19 // Managed<CppType> may be used polymorphically as Foreign, where the held 20 // address is typed as CppType**. The double indirection is due to the 21 // use, by Managed, of Isolate::ManagedObjectFinalizer, which has a CppType* 22 // first field. 23 template <class CppType> 24 class Managed : public Foreign { 25 public: get()26 V8_INLINE CppType* get() { 27 return *(reinterpret_cast<CppType**>(foreign_address())); 28 } 29 cast(Object * obj)30 static Managed<CppType>* cast(Object* obj) { 31 SLOW_DCHECK(obj->IsForeign()); 32 return reinterpret_cast<Managed<CppType>*>(obj); 33 } 34 New(Isolate * isolate,CppType * ptr)35 static Handle<Managed<CppType>> New(Isolate* isolate, CppType* ptr) { 36 Isolate::ManagedObjectFinalizer* node = 37 isolate->RegisterForReleaseAtTeardown(ptr, 38 Managed<CppType>::NativeDelete); 39 Handle<Managed<CppType>> handle = Handle<Managed<CppType>>::cast( 40 isolate->factory()->NewForeign(reinterpret_cast<Address>(node))); 41 RegisterWeakCallbackForDelete(isolate, handle); 42 return handle; 43 } 44 45 private: RegisterWeakCallbackForDelete(Isolate * isolate,Handle<Managed<CppType>> handle)46 static void RegisterWeakCallbackForDelete(Isolate* isolate, 47 Handle<Managed<CppType>> handle) { 48 Handle<Object> global_handle = isolate->global_handles()->Create(*handle); 49 GlobalHandles::MakeWeak(global_handle.location(), global_handle.location(), 50 &Managed<CppType>::GCDelete, 51 v8::WeakCallbackType::kFinalizer); 52 } 53 GCDelete(const v8::WeakCallbackInfo<void> & data)54 static void GCDelete(const v8::WeakCallbackInfo<void>& data) { 55 Managed<CppType>** p = 56 reinterpret_cast<Managed<CppType>**>(data.GetParameter()); 57 58 Isolate::ManagedObjectFinalizer* finalizer = (*p)->GetFinalizer(); 59 60 Isolate* isolate = reinterpret_cast<Isolate*>(data.GetIsolate()); 61 finalizer->Dispose(); 62 isolate->UnregisterFromReleaseAtTeardown(&finalizer); 63 64 (*p)->set_foreign_address(static_cast<Address>(nullptr)); 65 GlobalHandles::Destroy(reinterpret_cast<Object**>(p)); 66 } 67 NativeDelete(void * value)68 static void NativeDelete(void* value) { 69 CppType* typed_value = reinterpret_cast<CppType*>(value); 70 delete typed_value; 71 } 72 GetFinalizer()73 Isolate::ManagedObjectFinalizer* GetFinalizer() { 74 return reinterpret_cast<Isolate::ManagedObjectFinalizer*>( 75 foreign_address()); 76 } 77 }; 78 } // namespace internal 79 } // namespace v8 80 81 #endif // V8_WASM_MANAGED_H_ 82