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authorwolfbeast <mcwerewolf@gmail.com>2018-05-14 10:50:01 +0200
committerwolfbeast <mcwerewolf@gmail.com>2018-05-14 10:50:01 +0200
commite9dd029f5d00590e1a53e63b0ab805110a10b54c (patch)
tree1126ca5dda925a62be3dc12c99c90e953d08afcf /security/sandbox/chromium/base/memory/weak_ptr.h
parent9d6a7ae25d7f5da855a8f8df884de483b4e2a538 (diff)
parent36b8fd734f590eb726ca2e50f8d1ff9cc968b8e1 (diff)
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Merge branch 'master' into Basilisk-release
Diffstat (limited to 'security/sandbox/chromium/base/memory/weak_ptr.h')
-rw-r--r--security/sandbox/chromium/base/memory/weak_ptr.h345
1 files changed, 0 insertions, 345 deletions
diff --git a/security/sandbox/chromium/base/memory/weak_ptr.h b/security/sandbox/chromium/base/memory/weak_ptr.h
deleted file mode 100644
index 33d1e4736..000000000
--- a/security/sandbox/chromium/base/memory/weak_ptr.h
+++ /dev/null
@@ -1,345 +0,0 @@
-// Copyright (c) 2012 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.
-
-// Weak pointers are pointers to an object that do not affect its lifetime,
-// and which may be invalidated (i.e. reset to NULL) by the object, or its
-// owner, at any time, most commonly when the object is about to be deleted.
-
-// Weak pointers are useful when an object needs to be accessed safely by one
-// or more objects other than its owner, and those callers can cope with the
-// object vanishing and e.g. tasks posted to it being silently dropped.
-// Reference-counting such an object would complicate the ownership graph and
-// make it harder to reason about the object's lifetime.
-
-// EXAMPLE:
-//
-// class Controller {
-// public:
-// Controller() : weak_factory_(this) {}
-// void SpawnWorker() { Worker::StartNew(weak_factory_.GetWeakPtr()); }
-// void WorkComplete(const Result& result) { ... }
-// private:
-// // Member variables should appear before the WeakPtrFactory, to ensure
-// // that any WeakPtrs to Controller are invalidated before its members
-// // variable's destructors are executed, rendering them invalid.
-// WeakPtrFactory<Controller> weak_factory_;
-// };
-//
-// class Worker {
-// public:
-// static void StartNew(const WeakPtr<Controller>& controller) {
-// Worker* worker = new Worker(controller);
-// // Kick off asynchronous processing...
-// }
-// private:
-// Worker(const WeakPtr<Controller>& controller)
-// : controller_(controller) {}
-// void DidCompleteAsynchronousProcessing(const Result& result) {
-// if (controller_)
-// controller_->WorkComplete(result);
-// }
-// WeakPtr<Controller> controller_;
-// };
-//
-// With this implementation a caller may use SpawnWorker() to dispatch multiple
-// Workers and subsequently delete the Controller, without waiting for all
-// Workers to have completed.
-
-// ------------------------- IMPORTANT: Thread-safety -------------------------
-
-// Weak pointers may be passed safely between threads, but must always be
-// dereferenced and invalidated on the same SequencedTaskRunner otherwise
-// checking the pointer would be racey.
-//
-// To ensure correct use, the first time a WeakPtr issued by a WeakPtrFactory
-// is dereferenced, the factory and its WeakPtrs become bound to the calling
-// thread or current SequencedWorkerPool token, and cannot be dereferenced or
-// invalidated on any other task runner. Bound WeakPtrs can still be handed
-// off to other task runners, e.g. to use to post tasks back to object on the
-// bound sequence.
-//
-// If all WeakPtr objects are destroyed or invalidated then the factory is
-// unbound from the SequencedTaskRunner/Thread. The WeakPtrFactory may then be
-// destroyed, or new WeakPtr objects may be used, from a different sequence.
-//
-// Thus, at least one WeakPtr object must exist and have been dereferenced on
-// the correct thread to enforce that other WeakPtr objects will enforce they
-// are used on the desired thread.
-
-#ifndef BASE_MEMORY_WEAK_PTR_H_
-#define BASE_MEMORY_WEAK_PTR_H_
-
-#include "base/base_export.h"
-#include "base/logging.h"
-#include "base/macros.h"
-#include "base/memory/ref_counted.h"
-#include "base/sequence_checker.h"
-#include "base/template_util.h"
-
-namespace base {
-
-template <typename T> class SupportsWeakPtr;
-template <typename T> class WeakPtr;
-
-namespace internal {
-// These classes are part of the WeakPtr implementation.
-// DO NOT USE THESE CLASSES DIRECTLY YOURSELF.
-
-class BASE_EXPORT WeakReference {
- public:
- // Although Flag is bound to a specific SequencedTaskRunner, it may be
- // deleted from another via base::WeakPtr::~WeakPtr().
- class BASE_EXPORT Flag : public RefCountedThreadSafe<Flag> {
- public:
- Flag();
-
- void Invalidate();
- bool IsValid() const;
-
- private:
- friend class base::RefCountedThreadSafe<Flag>;
-
- ~Flag();
-
- SequenceChecker sequence_checker_;
- bool is_valid_;
- };
-
- WeakReference();
- explicit WeakReference(const Flag* flag);
- ~WeakReference();
-
- bool is_valid() const;
-
- private:
- scoped_refptr<const Flag> flag_;
-};
-
-class BASE_EXPORT WeakReferenceOwner {
- public:
- WeakReferenceOwner();
- ~WeakReferenceOwner();
-
- WeakReference GetRef() const;
-
- bool HasRefs() const {
- return flag_.get() && !flag_->HasOneRef();
- }
-
- void Invalidate();
-
- private:
- mutable scoped_refptr<WeakReference::Flag> flag_;
-};
-
-// This class simplifies the implementation of WeakPtr's type conversion
-// constructor by avoiding the need for a public accessor for ref_. A
-// WeakPtr<T> cannot access the private members of WeakPtr<U>, so this
-// base class gives us a way to access ref_ in a protected fashion.
-class BASE_EXPORT WeakPtrBase {
- public:
- WeakPtrBase();
- ~WeakPtrBase();
-
- protected:
- explicit WeakPtrBase(const WeakReference& ref);
-
- WeakReference ref_;
-};
-
-// This class provides a common implementation of common functions that would
-// otherwise get instantiated separately for each distinct instantiation of
-// SupportsWeakPtr<>.
-class SupportsWeakPtrBase {
- public:
- // A safe static downcast of a WeakPtr<Base> to WeakPtr<Derived>. This
- // conversion will only compile if there is exists a Base which inherits
- // from SupportsWeakPtr<Base>. See base::AsWeakPtr() below for a helper
- // function that makes calling this easier.
- template<typename Derived>
- static WeakPtr<Derived> StaticAsWeakPtr(Derived* t) {
- typedef
- is_convertible<Derived, internal::SupportsWeakPtrBase&> convertible;
- static_assert(convertible::value,
- "AsWeakPtr argument must inherit from SupportsWeakPtr");
- return AsWeakPtrImpl<Derived>(t, *t);
- }
-
- private:
- // This template function uses type inference to find a Base of Derived
- // which is an instance of SupportsWeakPtr<Base>. We can then safely
- // static_cast the Base* to a Derived*.
- template <typename Derived, typename Base>
- static WeakPtr<Derived> AsWeakPtrImpl(
- Derived* t, const SupportsWeakPtr<Base>&) {
- WeakPtr<Base> ptr = t->Base::AsWeakPtr();
- return WeakPtr<Derived>(ptr.ref_, static_cast<Derived*>(ptr.ptr_));
- }
-};
-
-} // namespace internal
-
-template <typename T> class WeakPtrFactory;
-
-// The WeakPtr class holds a weak reference to |T*|.
-//
-// This class is designed to be used like a normal pointer. You should always
-// null-test an object of this class before using it or invoking a method that
-// may result in the underlying object being destroyed.
-//
-// EXAMPLE:
-//
-// class Foo { ... };
-// WeakPtr<Foo> foo;
-// if (foo)
-// foo->method();
-//
-template <typename T>
-class WeakPtr : public internal::WeakPtrBase {
- public:
- WeakPtr() : ptr_(NULL) {
- }
-
- // Allow conversion from U to T provided U "is a" T. Note that this
- // is separate from the (implicit) copy constructor.
- template <typename U>
- WeakPtr(const WeakPtr<U>& other) : WeakPtrBase(other), ptr_(other.ptr_) {
- }
-
- T* get() const { return ref_.is_valid() ? ptr_ : NULL; }
-
- T& operator*() const {
- DCHECK(get() != NULL);
- return *get();
- }
- T* operator->() const {
- DCHECK(get() != NULL);
- return get();
- }
-
- // Allow WeakPtr<element_type> to be used in boolean expressions, but not
- // implicitly convertible to a real bool (which is dangerous).
- //
- // Note that this trick is only safe when the == and != operators
- // are declared explicitly, as otherwise "weak_ptr1 == weak_ptr2"
- // will compile but do the wrong thing (i.e., convert to Testable
- // and then do the comparison).
- private:
- typedef T* WeakPtr::*Testable;
-
- public:
- operator Testable() const { return get() ? &WeakPtr::ptr_ : NULL; }
-
- void reset() {
- ref_ = internal::WeakReference();
- ptr_ = NULL;
- }
-
- private:
- // Explicitly declare comparison operators as required by the bool
- // trick, but keep them private.
- template <class U> bool operator==(WeakPtr<U> const&) const;
- template <class U> bool operator!=(WeakPtr<U> const&) const;
-
- friend class internal::SupportsWeakPtrBase;
- template <typename U> friend class WeakPtr;
- friend class SupportsWeakPtr<T>;
- friend class WeakPtrFactory<T>;
-
- WeakPtr(const internal::WeakReference& ref, T* ptr)
- : WeakPtrBase(ref),
- ptr_(ptr) {
- }
-
- // This pointer is only valid when ref_.is_valid() is true. Otherwise, its
- // value is undefined (as opposed to NULL).
- T* ptr_;
-};
-
-// A class may be composed of a WeakPtrFactory and thereby
-// control how it exposes weak pointers to itself. This is helpful if you only
-// need weak pointers within the implementation of a class. This class is also
-// useful when working with primitive types. For example, you could have a
-// WeakPtrFactory<bool> that is used to pass around a weak reference to a bool.
-template <class T>
-class WeakPtrFactory {
- public:
- explicit WeakPtrFactory(T* ptr) : ptr_(ptr) {
- }
-
- ~WeakPtrFactory() {
- ptr_ = NULL;
- }
-
- WeakPtr<T> GetWeakPtr() {
- DCHECK(ptr_);
- return WeakPtr<T>(weak_reference_owner_.GetRef(), ptr_);
- }
-
- // Call this method to invalidate all existing weak pointers.
- void InvalidateWeakPtrs() {
- DCHECK(ptr_);
- weak_reference_owner_.Invalidate();
- }
-
- // Call this method to determine if any weak pointers exist.
- bool HasWeakPtrs() const {
- DCHECK(ptr_);
- return weak_reference_owner_.HasRefs();
- }
-
- private:
- internal::WeakReferenceOwner weak_reference_owner_;
- T* ptr_;
- DISALLOW_IMPLICIT_CONSTRUCTORS(WeakPtrFactory);
-};
-
-// A class may extend from SupportsWeakPtr to let others take weak pointers to
-// it. This avoids the class itself implementing boilerplate to dispense weak
-// pointers. However, since SupportsWeakPtr's destructor won't invalidate
-// weak pointers to the class until after the derived class' members have been
-// destroyed, its use can lead to subtle use-after-destroy issues.
-template <class T>
-class SupportsWeakPtr : public internal::SupportsWeakPtrBase {
- public:
- SupportsWeakPtr() {}
-
- WeakPtr<T> AsWeakPtr() {
- return WeakPtr<T>(weak_reference_owner_.GetRef(), static_cast<T*>(this));
- }
-
- protected:
- ~SupportsWeakPtr() {}
-
- private:
- internal::WeakReferenceOwner weak_reference_owner_;
- DISALLOW_COPY_AND_ASSIGN(SupportsWeakPtr);
-};
-
-// Helper function that uses type deduction to safely return a WeakPtr<Derived>
-// when Derived doesn't directly extend SupportsWeakPtr<Derived>, instead it
-// extends a Base that extends SupportsWeakPtr<Base>.
-//
-// EXAMPLE:
-// class Base : public base::SupportsWeakPtr<Producer> {};
-// class Derived : public Base {};
-//
-// Derived derived;
-// base::WeakPtr<Derived> ptr = base::AsWeakPtr(&derived);
-//
-// Note that the following doesn't work (invalid type conversion) since
-// Derived::AsWeakPtr() is WeakPtr<Base> SupportsWeakPtr<Base>::AsWeakPtr(),
-// and there's no way to safely cast WeakPtr<Base> to WeakPtr<Derived> at
-// the caller.
-//
-// base::WeakPtr<Derived> ptr = derived.AsWeakPtr(); // Fails.
-
-template <typename Derived>
-WeakPtr<Derived> AsWeakPtr(Derived* t) {
- return internal::SupportsWeakPtrBase::StaticAsWeakPtr<Derived>(t);
-}
-
-} // namespace base
-
-#endif // BASE_MEMORY_WEAK_PTR_H_