Split out Members, Persistents and SelfKeepAlive in separate headers.

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

-/*
- * Copyright (C) 2014 Google Inc. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are
- * met:
- *
- *     * Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *     * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following disclaimer
- * in the documentation and/or other materials provided with the
- * distribution.
- *     * Neither the name of Google Inc. nor the names of its
- * contributors may be used to endorse or promote products derived from
- * this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
+// Copyright 2016 The Chromium 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 Handle_h
-#define Handle_h
+#ifndef Persistent_h
+#define Persistent_h
 
-#include "platform/heap/Heap.h"
-#include "platform/heap/HeapAllocator.h"
-#include "platform/heap/InlinedGlobalMarkingVisitor.h"
+#include "platform/heap/Member.h"
 #include "platform/heap/PersistentNode.h"
-#include "platform/heap/ThreadState.h"
-#include "platform/heap/TraceTraits.h"
-#include "platform/heap/Visitor.h"
 #include "wtf/Allocator.h"
 #include "wtf/Atomics.h"
-#include "wtf/HashFunctions.h"
-
-#if defined(LEAK_SANITIZER)
-#include "wtf/LeakAnnotations.h"
-#endif
 
 namespace blink {
 
 // Marker used to annotate persistent objects and collections with,
 // so as to enable reliable testing for persistent references via
 // a type trait (see TypeTraits.h's IsPersistentReferenceType<>.)
 #define IS_PERSISTENT_REFERENCE_TYPE()               \
     public:                                          \
         using IsPersistentReferenceTypeMarker = int; \
     private:
@@ skipping 600 matching lines @@
 public:
     PersistentHeapDeque() { }
 
     template<size_t otherCapacity>
     PersistentHeapDeque(const HeapDeque<T, otherCapacity>& other)
         : PersistentHeapCollectionBase<HeapDeque<T, inlineCapacity>>(other)
     {
     }
 };
 
-// Members are used in classes to contain strong pointers to other oilpan heap
-// allocated objects.
-// All Member fields of a class must be traced in the class' trace method.
-// During the mark phase of the GC all live objects are marked as live and
-// all Member fields of a live object will be traced marked as live as well.
-template<typename T>
-class Member {
-    DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
-public:
-    Member() : m_raw(nullptr)
-    {
-    }
-
-    Member(std::nullptr_t) : m_raw(nullptr)
-    {
-    }
-
-    Member(T* raw) : m_raw(raw)
-    {
-        checkPointer();
-    }
-
-    explicit Member(T& raw) : m_raw(&raw)
-    {
-        checkPointer();
-    }
-
-    Member(WTF::HashTableDeletedValueType) : m_raw(reinterpret_cast<T*>(-1))
-    {
-    }
-
-    bool isHashTableDeletedValue() const { return m_raw == reinterpret_cast<T*>(-1); }
-
-    template<typename U>
-    Member(const Persistent<U>& other) : m_raw(other)
-    {
-        checkPointer();
-    }
-
-    Member(const Member& other) : m_raw(other)
-    {
-        checkPointer();
-    }
-
-    template<typename U>
-    Member(const Member<U>& other) : m_raw(other)
-    {
-        checkPointer();
-    }
-
-    T* release()
-    {
-        T* result = m_raw;
-        m_raw = nullptr;
-        return result;
-    }
-
-    explicit operator bool() 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>
-    Member& operator=(const Persistent<U>& other)
-    {
-        m_raw = other;
-        checkPointer();
-        return *this;
-    }
-
-    template<typename U>
-    Member& operator=(const Member<U>& other)
-    {
-        m_raw = other;
-        checkPointer();
-        return *this;
-    }
-
-    template<typename U>
-    Member& operator=(U* other)
-    {
-        m_raw = other;
-        checkPointer();
-        return *this;
-    }
-
-    Member& operator=(std::nullptr_t)
-    {
-        m_raw = nullptr;
-        return *this;
-    }
-
-    void swap(Member<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) && defined(ADDRESS_SANITIZER)
-        if (!m_raw)
-            return;
-        // HashTable can store a special value (which is not aligned to the
-        // allocation granularity) to Member<> to represent a deleted entry.
-        // Thus we treat a pointer that is not aligned to the granularity
-        // as a valid pointer.
-        if (reinterpret_cast<intptr_t>(m_raw) % allocationGranularity)
-            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 ThreadHeap::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;
-
-    template<bool x, WTF::WeakHandlingFlag y, WTF::ShouldWeakPointersBeMarkedStrongly z, typename U, typename V> friend struct CollectionBackingTraceTrait;
-    friend class Visitor;
-
-};
-
-// WeakMember is similar to Member in that it is used to point to other oilpan
-// heap allocated objects.
-// However instead of creating a strong pointer to the object, the WeakMember creates
-// a weak pointer, which does not keep the pointee alive. Hence if all pointers to
-// to a heap allocated object are weak the object will be garbage collected. At the
-// time of GC the weak pointers will automatically be set to null.
-template<typename T>
-class WeakMember : public Member<T> {
-public:
-    WeakMember() : Member<T>() { }
-
-    WeakMember(std::nullptr_t) : Member<T>(nullptr) { }
-
-    WeakMember(T* raw) : Member<T>(raw) { }
-
-    WeakMember(WTF::HashTableDeletedValueType x) : Member<T>(x) { }
-
-    template<typename U>
-    WeakMember(const Persistent<U>& other) : Member<T>(other) { }
-
-    template<typename U>
-    WeakMember(const Member<U>& other) : Member<T>(other) { }
-
-    template<typename U>
-    WeakMember& operator=(const Persistent<U>& other)
-    {
-        this->m_raw = other;
-        this->checkPointer();
-        return *this;
-    }
-
-    template<typename U>
-    WeakMember& operator=(const Member<U>& other)
-    {
-        this->m_raw = other;
-        this->checkPointer();
-        return *this;
-    }
-
-    template<typename U>
-    WeakMember& operator=(U* other)
-    {
-        this->m_raw = other;
-        this->checkPointer();
-        return *this;
-    }
-
-    WeakMember& operator=(std::nullptr_t)
-    {
-        this->m_raw = nullptr;
-        return *this;
-    }
-
-private:
-    T** cell() const { return const_cast<T**>(&this->m_raw); }
-
-    template<typename Derived> friend class VisitorHelper;
-};
-
-// UntracedMember is a pointer to an on-heap object that is not traced for some
-// reason. Please don't use this unless you understand what you're doing.
-// Basically, all pointers to on-heap objects must be stored in either of
-// Persistent, Member or WeakMember. It is not allowed to leave raw pointers to
-// on-heap objects. However, there can be scenarios where you have to use raw
-// pointers for some reason, and in that case you can use UntracedMember. Of
-// course, it must be guaranteed that the pointing on-heap object is kept alive
-// while the raw pointer is pointing to the object.
-template<typename T>
-class UntracedMember final : public Member<T> {
-public:
-    UntracedMember() : Member<T>() { }
-
-    UntracedMember(std::nullptr_t) : Member<T>(nullptr) { }
-
-    UntracedMember(T* raw) : Member<T>(raw) { }
-
-    template<typename U>
-    UntracedMember(const Persistent<U>& other) : Member<T>(other) { }
-
-    template<typename U>
-    UntracedMember(const Member<U>& other) : Member<T>(other) { }
-
-    UntracedMember(WTF::HashTableDeletedValueType x) : Member<T>(x) { }
-
-    template<typename U>
-    UntracedMember& operator=(const Persistent<U>& other)
-    {
-        this->m_raw = other;
-        this->checkPointer();
-        return *this;
-    }
-
-    template<typename U>
-    UntracedMember& operator=(const Member<U>& other)
-    {
-        this->m_raw = other;
-        this->checkPointer();
-        return *this;
-    }
-
-    template<typename U>
-    UntracedMember& operator=(U* other)
-    {
-        this->m_raw = other;
-        this->checkPointer();
-        return *this;
-    }
-
-    UntracedMember& operator=(std::nullptr_t)
-    {
-        this->m_raw = nullptr;
-        return *this;
-    }
-};
-
-// 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 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, bool = IsGarbageCollectedType<T>::value>
-class RawPtrOrMemberTrait {
-    STATIC_ONLY(RawPtrOrMemberTrait)
-public:
-    using Type = T*;
-};
-
-template<typename T>
-class RawPtrOrMemberTrait<T, true> {
-    STATIC_ONLY(RawPtrOrMemberTrait)
-public:
-    using Type = Member<T>;
-};
-
-// Abstraction for injecting calls to an object's 'dispose()' method
-// on leaving a stack scope, ensuring earlier release of resources
-// than waiting until the object is eventually GCed.
-template<typename T, void (T::*Disposer)() = (&T::dispose)>
-class ScopedDisposal {
-    STACK_ALLOCATED();
-public:
-    ScopedDisposal(T* object)
-        : m_object(object)
-    {
-    }
-
-    ~ScopedDisposal()
-    {
-        if (m_object)
-            (m_object->*Disposer)();
-    }
-
-    void clear() { m_object.clear(); }
-
-private:
-    typename RawPtrOrMemberTrait<T>::Type m_object;
-};
-
-// SelfKeepAlive<Object> is the idiom to use for objects that have to keep
-// themselves temporarily alive and cannot rely on there being some
-// external reference in that interval:
-//
-//  class Opener {
-//  public:
-//     ...
-//     void open()
-//     {
-//         // Retain a self-reference while in an open()ed state:
-//         m_keepAlive = this;
-//         ....
-//     }
-//
-//     void close()
-//     {
-//         // Clear self-reference that ensured we were kept alive while opened.
-//         m_keepAlive.clear();
-//         ....
-//     }
-//
-//  private:
-//     ...
-//     SelfKeepAlive m_keepAlive;
-//  };
-//
-// The responsibility to call clear() in a timely fashion resides with the implementation
-// of the object.
-//
-//
-template<typename Self>
-class SelfKeepAlive final {
-    DISALLOW_NEW();
-public:
-    SelfKeepAlive()
-    {
-    }
-
-    explicit SelfKeepAlive(Self* self)
-    {
-        assign(self);
-    }
-
-    SelfKeepAlive& operator=(Self* self)
-    {
-        assign(self);
-        return *this;
-    }
-
-    void clear()
-    {
-        m_keepAlive.clear();
-    }
-
-    typedef Persistent<Self> (SelfKeepAlive::*UnspecifiedBoolType);
-    operator UnspecifiedBoolType() const { return m_keepAlive ? &SelfKeepAlive::m_keepAlive : 0; }
-
-private:
-    void assign(Self* self)
-    {
-        ASSERT(!m_keepAlive || m_keepAlive.get() == self);
-        m_keepAlive = self;
-    }
-
-    GC_PLUGIN_IGNORE("420515")
-    Persistent<Self> m_keepAlive;
-};
-
 // Only a very reduced form of weak heap object references can currently be held
 // by WTF::Closure<>s. i.e., bound as a 'this' pointer only.
 //
 // TODO(sof): once wtf/Functional.h is able to work over platform/heap/ types
 // (like CrossThreadWeakPersistent<>), drop the restriction on weak persistent
 // use by function closures (and rename this ad-hoc type.)
 template<typename T>
 class WeakPersistentThisPointer {
     STACK_ALLOCATED();
 public:
@@ skipping 18 matching lines @@
 {
     return Persistent<T>(value);
 }
 
 template <typename T>
 CrossThreadPersistent<T> wrapCrossThreadPersistent(T* value)
 {
     return CrossThreadPersistent<T>(value);
 }
 
-// LEAK_SANITIZER_DISABLED_SCOPE: all allocations made in the current scope
-// will be exempted from LSan consideration.
-//
-// TODO(sof): move this to wtf/LeakAnnotations.h (LeakSanitizer.h?) once
-// wtf/ can freely call upon Oilpan functionality.
-#if defined(LEAK_SANITIZER)
-class LeakSanitizerDisableScope {
-    STACK_ALLOCATED();
-    WTF_MAKE_NONCOPYABLE(LeakSanitizerDisableScope);
-public:
-    LeakSanitizerDisableScope()
-    {
-        __lsan_disable();
-        if (ThreadState::current())
-            ThreadState::current()->enterStaticReferenceRegistrationDisabledScope();
-    }
+// 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 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(); }
 
-    ~LeakSanitizerDisableScope()
-    {
-        __lsan_enable();
-        if (ThreadState::current())
-            ThreadState::current()->leaveStaticReferenceRegistrationDisabledScope();
-    }
-};
-#define LEAK_SANITIZER_DISABLED_SCOPE LeakSanitizerDisableScope lsanDisabledScope
-#else
-#define LEAK_SANITIZER_DISABLED_SCOPE
-#endif
+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(); }
 
 } // namespace blink
 
 namespace WTF {
 
-template <typename T>
-struct MemberHash : PtrHash<T> {
-    STATIC_ONLY(MemberHash);
-    template <typename U>
-    static unsigned hash(const U& key) { return PtrHash<T>::hash(key); }
-    template <typename U, typename V>
-    static bool equal(const U& a, const V& b) { return a == b; }
-};
-
-template <typename T>
-struct WeakMemberHash : MemberHash<T> {
-    STATIC_ONLY(WeakMemberHash);
-};
-
-template <typename T>
-struct UntracedMemberHash : MemberHash<T> {
-    STATIC_ONLY(UntracedMemberHash);
-};
-
-// PtrHash is the default hash for hash tables with members.
-template <typename T>
-struct DefaultHash<blink::Member<T>> {
-    STATIC_ONLY(DefaultHash);
-    using Hash = MemberHash<T>;
-};
-
-template <typename T>
-struct DefaultHash<blink::WeakMember<T>> {
-    STATIC_ONLY(DefaultHash);
-    using Hash = WeakMemberHash<T>;
-};
-
-template <typename T>
-struct DefaultHash<blink::UntracedMember<T>> {
-    STATIC_ONLY(DefaultHash);
-    using Hash = UntracedMemberHash<T>;
-};
-
-template<typename T>
-struct NeedsTracing<blink::Member<T>> {
-    STATIC_ONLY(NeedsTracing);
-    static const bool value = true;
-};
-
-template<typename T>
-struct IsWeak<blink::WeakMember<T>> {
-    STATIC_ONLY(IsWeak);
-    static const bool value = true;
-};
-
 template<typename T>
 struct ParamStorageTraits<blink::WeakPersistentThisPointer<T>> {
     STATIC_ONLY(ParamStorageTraits);
     static_assert(sizeof(T), "T must be fully defined");
     using StorageType = blink::WeakPersistent<T>;
 
     static StorageType wrap(const blink::WeakPersistentThisPointer<T>& value) { return value.value(); }
 
     // WTF::FunctionWrapper<> handles WeakPtr<>, so recast this weak persistent
     // into it.
@@ skipping 14 matching lines @@
     // WTF::FunctionWrapper<> handles WeakPtr<>, so recast this weak persistent
     // into it.
     //
     // TODO(sof): remove this hack once wtf/Functional.h can also work with a type like
     // CrossThreadWeakPersistent<>.
     static WeakPtr<T> unwrap(const StorageType& value) { return WeakPtr<T>(WeakReference<T>::create(value.get())); }
 };
 
 } // namespace WTF
 
-#endif
+#endif // Persistent_h