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// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_WASM_MANAGED_H_
#define V8_WASM_MANAGED_H_
#include "src/factory.h"
#include "src/global-handles.h"
#include "src/handles.h"
#include "src/isolate.h"
namespace v8 {
namespace internal {
// An object that wraps a pointer to a C++ object and manages its lifetime.
// The C++ object will be deleted when the managed wrapper object is
// garbage collected, or, last resort, if the isolate is torn down before GC,
// as part of Isolate::Dispose().
// Managed<CppType> may be used polymorphically as Foreign, where the held
// address is typed as CppType**. The double indirection is due to the
// use, by Managed, of Isolate::ManagedObjectFinalizer, which has a CppType*
// first field.
template <class CppType>
class Managed : public Foreign {
public:
V8_INLINE CppType* get() {
return *(reinterpret_cast<CppType**>(foreign_address()));
}
static Managed<CppType>* cast(Object* obj) {
SLOW_DCHECK(obj->IsForeign());
return reinterpret_cast<Managed<CppType>*>(obj);
}
static Handle<Managed<CppType>> New(Isolate* isolate, CppType* ptr) {
Isolate::ManagedObjectFinalizer* node =
isolate->RegisterForReleaseAtTeardown(ptr,
Managed<CppType>::NativeDelete);
Handle<Managed<CppType>> handle = Handle<Managed<CppType>>::cast(
isolate->factory()->NewForeign(reinterpret_cast<Address>(node)));
RegisterWeakCallbackForDelete(isolate, handle);
return handle;
}
private:
static void RegisterWeakCallbackForDelete(Isolate* isolate,
Handle<Managed<CppType>> handle) {
Handle<Object> global_handle = isolate->global_handles()->Create(*handle);
GlobalHandles::MakeWeak(global_handle.location(), global_handle.location(),
&Managed<CppType>::GCDelete,
v8::WeakCallbackType::kFinalizer);
}
static void GCDelete(const v8::WeakCallbackInfo<void>& data) {
Managed<CppType>** p =
reinterpret_cast<Managed<CppType>**>(data.GetParameter());
Isolate::ManagedObjectFinalizer* finalizer = (*p)->GetFinalizer();
Isolate* isolate = reinterpret_cast<Isolate*>(data.GetIsolate());
finalizer->Dispose();
isolate->UnregisterFromReleaseAtTeardown(&finalizer);
(*p)->set_foreign_address(static_cast<Address>(nullptr));
GlobalHandles::Destroy(reinterpret_cast<Object**>(p));
}
static void NativeDelete(void* value) {
CppType* typed_value = reinterpret_cast<CppType*>(value);
delete typed_value;
}
Isolate::ManagedObjectFinalizer* GetFinalizer() {
return reinterpret_cast<Isolate::ManagedObjectFinalizer*>(
foreign_address());
}
};
} // namespace internal
} // namespace v8
#endif // V8_WASM_MANAGED_H_
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