[Oilpan] Create UnsafePtr to store on-heap pointers in Vector

third_party/WebKit/Source/platform/heap/Handle.h

Index: third_party/WebKit/Source/platform/heap/Handle.h
diff --git a/third_party/WebKit/Source/platform/heap/Handle.h b/third_party/WebKit/Source/platform/heap/Handle.h
index fd9415a02382af0ad0f35457dd7285cb41c122fa..7fa6060f4685b0252355dcf6d213e87c3b543baa 100644
--- a/third_party/WebKit/Source/platform/heap/Handle.h
+++ b/third_party/WebKit/Source/platform/heap/Handle.h
@@ -48,6 +48,9 @@
 
 namespace blink {
 
+template<typename T> class Member;
+template<typename T> class UntracedMember;
+
 enum WeaknessPersistentConfiguration {
     NonWeakPersistentConfiguration,
     WeakPersistentConfiguration
@@ -101,6 +104,14 @@ public:
     }
 
     template<typename U>
+    PersistentBase(const UntracedMember<U>& other) : m_raw(other)
+    {
+        initialize();
+        checkPointer();
+        recordBacktrace();
+    }
+
+    template<typename U>
     PersistentBase(const Member<U>& other) : m_raw(other)
     {
         initialize();
@@ -176,6 +187,13 @@ public:
     }
 
     template<typename U>
+    PersistentBase& operator=(const UntracedMember<U>& other)
+    {
+        assign(other);
+        return *this;
+    }
+
+    template<typename U>
     PersistentBase& operator=(const Member<U>& other)
     {
         assign(other);
@@ -298,6 +316,8 @@ public:
     template<typename U>
     Persistent(const Persistent<U>& other) : Parent(other) { }
     template<typename U>
+    Persistent(const UntracedMember<U>& other) : Parent(other) { }
+    template<typename U>
     Persistent(const Member<U>& other) : Parent(other) { }
     template<typename U>
     Persistent(const RawPtr<U>& other) : Parent(other.get()) { }
@@ -329,6 +349,13 @@ public:
     }
 
     template<typename U>
+    Persistent& operator=(const UntracedMember<U>& other)
+    {
+        Parent::operator=(other);
+        return *this;
+    }
+
+    template<typename U>
     Persistent& operator=(const Member<U>& other)
     {
         Parent::operator=(other);
@@ -425,6 +452,8 @@ public:
     template<typename U>
     CrossThreadPersistent(const CrossThreadPersistent<U>& other) : Parent(other) { }
     template<typename U>
+    CrossThreadPersistent(const UntracedMember<U>& other) : Parent(other) { }
+    template<typename U>
     CrossThreadPersistent(const Member<U>& other) : Parent(other) { }
     template<typename U>
     CrossThreadPersistent(const RawPtr<U>& other) : Parent(other.get()) { }
@@ -456,6 +485,13 @@ public:
     }
 
     template<typename U>
+    CrossThreadPersistent& operator=(const UntracedMember<U>& other)
+    {
+        Parent::operator=(other);
+        return *this;
+    }
+
+    template<typename U>
     CrossThreadPersistent& operator=(const Member<U>& other)
     {
         Parent::operator=(other);
@@ -483,6 +519,8 @@ public:
     template<typename U>
     CrossThreadWeakPersistent(const CrossThreadWeakPersistent<U>& other) : Parent(other) { }
     template<typename U>
+    CrossThreadWeakPersistent(const UntracedMember<U>& other) : Parent(other) { }
+    template<typename U>
     CrossThreadWeakPersistent(const Member<U>& other) : Parent(other) { }
     template<typename U>
     CrossThreadWeakPersistent(const RawPtr<U>& other) : Parent(other.get()) { }
@@ -514,6 +552,13 @@ public:
     }
 
     template<typename U>
+    CrossThreadWeakPersistent& operator=(const UntracedMember<U>& other)
+    {
+        Parent::operator=(other);
+        return *this;
+    }
+
+    template<typename U>
     CrossThreadWeakPersistent& operator=(const Member<U>& other)
     {
         Parent::operator=(other);
@@ -691,6 +736,12 @@ public:
         checkPointer();
     }
 
+    template<typename U>
+    Member(const UntracedMember<U>& other) : m_raw(other)
+    {
+        checkPointer();
+    }
+
     Member(const Member& other) : m_raw(other)
     {
         checkPointer();
@@ -735,6 +786,14 @@ public:
     }
 
     template<typename U>
+    Member& operator=(const UntracedMember<U>& other)
+    {
+        m_raw = other;
+        checkPointer();
+        return *this;
+    }
+
+    template<typename U>
     Member& operator=(U* other)
     {
         m_raw = other;
@@ -823,6 +882,9 @@ public:
     WeakMember(const Persistent<U>& other) : Member<T>(other) { }
 
     template<typename U>
+    WeakMember(const UntracedMember<U>& other) : Member<T>(other) { }
+
+    template<typename U>
     WeakMember(const Member<U>& other) : Member<T>(other) { }
 
     template<typename U>
@@ -842,6 +904,14 @@ public:
     }
 
     template<typename U>
+    WeakMember& operator=(const UntracedMember<U>& other)
+    {
+        this->m_raw = other;
+        this->checkPointer();
+        return *this;
+    }
+
+    template<typename U>
     WeakMember& operator=(U* other)
     {
         this->m_raw = other;
@@ -869,15 +939,182 @@ private:
     template<typename Derived> friend class VisitorHelper;
 };
 
-// Comparison operators between (Weak)Members and Persistents
+// UntracedMember is actually a raw pointer.
+// It is allowed to store a pointer to an object on oilpan heap,
+// and it is also allowed to store UntracedMember in off heap Vector.
+// UntracedMember does not keep the pointee object alive, so if you use
+// UntracedMember, you must guarantee that the pointee object is alive in
+// some reason.
+// TODO(peria): Enable to store UntracedMember in hash collections. (i.e. HashSet)
+template<typename T>
+class UntracedMember {

[haraken, 2015/10/14 09:39:53]

I'm just curious but would it be possible to make UntracedMember inherit from
Member? Then maybe can we decrease the code duplication? (I should have asked
this earlier... sorry :-/)

[peria, 2015/10/15 02:13:15]

Done.

+public:
+    UntracedMember() : m_raw(nullptr)
+    {
+    }
+
+    UntracedMember(std::nullptr_t) : m_raw(nullptr)
+    {
+    }
+
+    UntracedMember(const UntracedMember& other) : m_raw(other)
+    {
+        checkPointer();
+    }
+
+    template<typename U>
+    UntracedMember(const UntracedMember<U>& other) : m_raw(other)
+    {
+        checkPointer();
+    }
+
+    UntracedMember(T* raw) : m_raw(raw)
+    {
+        checkPointer();
+    }
+
+    template<typename U>
+    UntracedMember(const RawPtr<U>& other) : m_raw(other.get())
+    {
+        checkPointer();
+    }
+
+    template<typename U>
+    UntracedMember(const Persistent<U>& other) : m_raw(other)
+    {
+        checkPointer();
+    }
+
+    template<typename U>
+    UntracedMember(const Member<U>& other) : m_raw(other)
+    {
+        checkPointer();
+    }
+
+    UntracedMember(WTF::HashTableDeletedValueType) : m_raw(reinterpret_cast<T*>(-1))
+    {
+    }
+
+    bool isHashTableDeletedValue() const { return m_raw == reinterpret_cast<T*>(-1); }
+
+    T* release()
+    {
+        T* result = m_raw;
+        m_raw = nullptr;
+        return result;
+    }
+
+    bool operator!() const { return !m_raw; }
+
+    operator T*() const { return m_raw; }
+
+    T* operator->() const { return m_raw; }
+    T& operator*() const { return *m_raw; }
+    template<typename U>
+    operator RawPtr<U>() const { return m_raw; }
+
+    template<typename U>
+    UntracedMember& operator=(const UntracedMember<U>& other)
+    {
+        m_raw = other;
+        checkPointer();
+        return *this;
+    }
+
+    template<typename U>
+    UntracedMember& operator=(const Persistent<U>& other)
+    {
+        m_raw = other;
+        checkPointer();
+        return *this;
+    }
+
+    template<typename U>
+    UntracedMember& operator=(const Member<U>& other)
+    {
+        m_raw = other;
+        checkPointer();
+        return *this;
+    }
+
+    template<typename U>
+    UntracedMember& operator=(RawPtr<U> other)
+    {
+        m_raw = other;
+        checkPointer();
+        return *this;
+    }
+
+    template<typename U>
+    UntracedMember& operator=(U* other)
+    {
+        m_raw = other;
+        checkPointer();
+        return *this;
+    }
+
+    UntracedMember& operator=(std::nullptr_t)
+    {
+        m_raw = nullptr;
+        return *this;
+    }
+
+    void swap(UntracedMember<T>& other)
+    {
+        std::swap(m_raw, other.m_raw);
+        checkPointer();
+    }
+
+    T* get() const { return m_raw; }
+
+    void clear() { m_raw = nullptr; }
+
+
+protected:
+    void checkPointer()
+    {
+#if ENABLE(ASSERT)
+        if (!m_raw)
+            return;
+
+        // TODO(haraken): What we really want to check here is that the pointer
+        // is a traceable object. In other words, the pointer is either of:
+        //
+        //   (a) a pointer to the head of an on-heap object.
+        //   (b) a pointer to the head of an on-heap mixin object.
+        //
+        // We can check it by calling Heap::isHeapObjectAlive(m_raw),
+        // but we cannot call it here because it requires to include T.h.
+        // So we currently only try to implement the check for (a), but do
+        // not insist that T's definition is in scope.
+        if (IsFullyDefined<T>::value && !IsGarbageCollectedMixin<T>::value)
+            ASSERT(HeapObjectHeader::fromPayload(m_raw)->checkHeader());
+#endif
+    }
+
+    T* m_raw;
+};
+
+// Comparison operators between (Weak)Members, Persistents, and UntracedMembers.
 template<typename T, typename U> inline bool operator==(const Member<T>& a, const Member<U>& b) { return a.get() == b.get(); }
 template<typename T, typename U> inline bool operator!=(const Member<T>& a, const Member<U>& b) { return a.get() != b.get(); }
+template<typename T, typename U> inline bool operator==(const UntracedMember<T>& a, const UntracedMember<U>& b) { return a.get() == b.get(); }
+template<typename T, typename U> inline bool operator!=(const UntracedMember<T>& a, const UntracedMember<U>& b) { return a.get() != b.get(); }
+template<typename T, typename U> inline bool operator==(const Persistent<T>& a, const Persistent<U>& b) { return a.get() == b.get(); }
+template<typename T, typename U> inline bool operator!=(const Persistent<T>& a, const Persistent<U>& b) { return a.get() != b.get(); }
+
 template<typename T, typename U> inline bool operator==(const Member<T>& a, const Persistent<U>& b) { return a.get() == b.get(); }
 template<typename T, typename U> inline bool operator!=(const Member<T>& a, const Persistent<U>& b) { return a.get() != b.get(); }
 template<typename T, typename U> inline bool operator==(const Persistent<T>& a, const Member<U>& b) { return a.get() == b.get(); }
 template<typename T, typename U> inline bool operator!=(const Persistent<T>& a, const Member<U>& b) { return a.get() != b.get(); }
-template<typename T, typename U> inline bool operator==(const Persistent<T>& a, const Persistent<U>& b) { return a.get() == b.get(); }
-template<typename T, typename U> inline bool operator!=(const Persistent<T>& a, const Persistent<U>& b) { return a.get() != b.get(); }
+template<typename T, typename U> inline bool operator==(const Member<T>& a, const UntracedMember<U>& b) { return a.get() == b.get(); }
+template<typename T, typename U> inline bool operator!=(const Member<T>& a, const UntracedMember<U>& b) { return a.get() != b.get(); }
+template<typename T, typename U> inline bool operator==(const UntracedMember<T>& a, const Member<U>& b) { return a.get() == b.get(); }
+template<typename T, typename U> inline bool operator!=(const UntracedMember<T>& a, const Member<U>& b) { return a.get() != b.get(); }
+template<typename T, typename U> inline bool operator==(const UntracedMember<T>& a, const Persistent<U>& b) { return a.get() == b.get(); }
+template<typename T, typename U> inline bool operator!=(const UntracedMember<T>& a, const Persistent<U>& b) { return a.get() != b.get(); }
+template<typename T, typename U> inline bool operator==(const Persistent<T>& a, const UntracedMember<U>& b) { return a.get() == b.get(); }
+template<typename T, typename U> inline bool operator!=(const Persistent<T>& a, const UntracedMember<U>& b) { return a.get() != b.get(); }
 
 template<typename T>
 class DummyBase {
@@ -925,6 +1162,7 @@ public:
 #define RawPtrWillBePersistent blink::Persistent
 #define RawPtrWillBeWeakMember blink::WeakMember
 #define RawPtrWillBeWeakPersistent blink::WeakPersistent
+#define RawPtrWillBeUntracedMember blink::UntracedMember
 #define OwnPtrWillBeCrossThreadPersistent blink::CrossThreadPersistent
 #define OwnPtrWillBeMember blink::Member
 #define OwnPtrWillBePersistent blink::Persistent
@@ -1008,6 +1246,7 @@ template<typename T> T* adoptPtrWillBeNoop(T* ptr)
 #define RawPtrWillBePersistent WTF::RawPtr
 #define RawPtrWillBeWeakMember WTF::RawPtr
 #define RawPtrWillBeWeakPersistent WTF::RawPtr
+#define RawPtrWillBeUntracedMember WTF::RawPtr
 #define OwnPtrWillBeCrossThreadPersistent WTF::OwnPtr
 #define OwnPtrWillBeMember WTF::OwnPtr
 #define OwnPtrWillBePersistent WTF::OwnPtr
@@ -1198,6 +1437,13 @@ template <typename T> struct VectorTraits<blink::WeakMember<T>> : VectorTraitsBa
     static const bool canMoveWithMemcpy = true;
 };
 
+template <typename T> struct VectorTraits<blink::UntracedMember<T>> : VectorTraitsBase<blink::UntracedMember<T>> {
+    static const bool needsDestruction = false;
+    static const bool canInitializeWithMemset = true;
+    static const bool canClearUnusedSlotsWithMemset = true;
+    static const bool canMoveWithMemcpy = true;
+};
+
 template <typename T> struct VectorTraits<blink::HeapVector<T, 0>> : VectorTraitsBase<blink::HeapVector<T, 0>> {
     static const bool needsDestruction = false;
     static const bool canInitializeWithMemset = true;
@@ -1289,6 +1535,32 @@ template<typename T> struct HashTraits<blink::WeakMember<T>> : SimpleClassHashTr
     }
 };
 
+template<typename T> struct HashTraits<blink::UntracedMember<T>> : SimpleClassHashTraits<blink::UntracedMember<T>> {
+    static const bool needsDestruction = false;
+    // FIXME: The distinction between PeekInType and PassInType is there for
+    // the sake of the reference counting handles. When they are gone the two
+    // types can be merged into PassInType.
+    // FIXME: Implement proper const'ness for iterator types.
+    using PeekInType = RawPtr<T>;
+    using PassInType = RawPtr<T>;
+    using IteratorGetType = blink::UntracedMember<T>*;
+    using IteratorConstGetType = const blink::UntracedMember<T>*;
+    using IteratorReferenceType = blink::UntracedMember<T>&;
+    using IteratorConstReferenceType = const blink::UntracedMember<T>&;
+    static IteratorReferenceType getToReferenceConversion(IteratorGetType x) { return *x; }
+    static IteratorConstReferenceType getToReferenceConstConversion(IteratorConstGetType x) { return *x; }
+    // FIXME: Similarly, there is no need for a distinction between PeekOutType
+    // and PassOutType without reference counting.
+    using PeekOutType = T*;
+    using PassOutType = T*;
+
+    template<typename U>
+    static void store(const U& value, blink::UntracedMember<T>& storage) { storage = value; }
+
+    static PeekOutType peek(const blink::UntracedMember<T>& value) { return value; }
+    static PassOutType passOut(const blink::UntracedMember<T>& value) { return value; }
+};
+
 template<typename T> struct PtrHash<blink::Member<T>> : PtrHash<T*> {
     template<typename U>
     static unsigned hash(const U& key) { return PtrHash<T*>::hash(key); }
@@ -1310,6 +1582,10 @@ template<typename T> struct DefaultHash<blink::WeakMember<T>> {
     using Hash = PtrHash<blink::WeakMember<T>>;
 };
 
+template<typename T> struct DefaultHash<blink::UntracedMember<T>> {
+    using Hash = PtrHash<blink::UntracedMember<T>>;
+};
+
 template<typename T>
 struct NeedsTracing<blink::Member<T>> {
     static const bool value = true;