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Diffstat (limited to 'security/sandbox/chromium/base/memory/ref_counted.h')
-rw-r--r-- | security/sandbox/chromium/base/memory/ref_counted.h | 446 |
1 files changed, 446 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/memory/ref_counted.h b/security/sandbox/chromium/base/memory/ref_counted.h new file mode 100644 index 000000000..a1c126969 --- /dev/null +++ b/security/sandbox/chromium/base/memory/ref_counted.h @@ -0,0 +1,446 @@ +// 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. + +#ifndef BASE_MEMORY_REF_COUNTED_H_ +#define BASE_MEMORY_REF_COUNTED_H_ + +#include <cassert> +#include <iosfwd> + +#include "base/atomic_ref_count.h" +#include "base/base_export.h" +#include "base/compiler_specific.h" +#include "base/macros.h" +#ifndef NDEBUG +#include "base/logging.h" +#endif +#include "base/threading/thread_collision_warner.h" +#include "build/build_config.h" + +namespace base { + +namespace subtle { + +class BASE_EXPORT RefCountedBase { + public: + bool HasOneRef() const { return ref_count_ == 1; } + + protected: + RefCountedBase() + : ref_count_(0) + #ifndef NDEBUG + , in_dtor_(false) + #endif + { + } + + ~RefCountedBase() { + #ifndef NDEBUG + DCHECK(in_dtor_) << "RefCounted object deleted without calling Release()"; + #endif + } + + + void AddRef() const { + // TODO(maruel): Add back once it doesn't assert 500 times/sec. + // Current thread books the critical section "AddRelease" + // without release it. + // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_); + #ifndef NDEBUG + DCHECK(!in_dtor_); + #endif + ++ref_count_; + } + + // Returns true if the object should self-delete. + bool Release() const { + // TODO(maruel): Add back once it doesn't assert 500 times/sec. + // Current thread books the critical section "AddRelease" + // without release it. + // DFAKE_SCOPED_LOCK_THREAD_LOCKED(add_release_); + #ifndef NDEBUG + DCHECK(!in_dtor_); + #endif + if (--ref_count_ == 0) { + #ifndef NDEBUG + in_dtor_ = true; + #endif + return true; + } + return false; + } + + private: + mutable int ref_count_; +#ifndef NDEBUG + mutable bool in_dtor_; +#endif + + DFAKE_MUTEX(add_release_); + + DISALLOW_COPY_AND_ASSIGN(RefCountedBase); +}; + +class BASE_EXPORT RefCountedThreadSafeBase { + public: + bool HasOneRef() const; + + protected: + RefCountedThreadSafeBase(); + ~RefCountedThreadSafeBase(); + + void AddRef() const; + + // Returns true if the object should self-delete. + bool Release() const; + + private: + mutable AtomicRefCount ref_count_; +#ifndef NDEBUG + mutable bool in_dtor_; +#endif + + DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase); +}; + +} // namespace subtle + +// +// A base class for reference counted classes. Otherwise, known as a cheap +// knock-off of WebKit's RefCounted<T> class. To use this guy just extend your +// class from it like so: +// +// class MyFoo : public base::RefCounted<MyFoo> { +// ... +// private: +// friend class base::RefCounted<MyFoo>; +// ~MyFoo(); +// }; +// +// You should always make your destructor non-public, to avoid any code deleting +// the object accidently while there are references to it. +template <class T> +class RefCounted : public subtle::RefCountedBase { + public: + RefCounted() {} + + void AddRef() const { + subtle::RefCountedBase::AddRef(); + } + + void Release() const { + if (subtle::RefCountedBase::Release()) { + delete static_cast<const T*>(this); + } + } + + protected: + ~RefCounted() {} + + private: + DISALLOW_COPY_AND_ASSIGN(RefCounted<T>); +}; + +// Forward declaration. +template <class T, typename Traits> class RefCountedThreadSafe; + +// Default traits for RefCountedThreadSafe<T>. Deletes the object when its ref +// count reaches 0. Overload to delete it on a different thread etc. +template<typename T> +struct DefaultRefCountedThreadSafeTraits { + static void Destruct(const T* x) { + // Delete through RefCountedThreadSafe to make child classes only need to be + // friend with RefCountedThreadSafe instead of this struct, which is an + // implementation detail. + RefCountedThreadSafe<T, + DefaultRefCountedThreadSafeTraits>::DeleteInternal(x); + } +}; + +// +// A thread-safe variant of RefCounted<T> +// +// class MyFoo : public base::RefCountedThreadSafe<MyFoo> { +// ... +// }; +// +// If you're using the default trait, then you should add compile time +// asserts that no one else is deleting your object. i.e. +// private: +// friend class base::RefCountedThreadSafe<MyFoo>; +// ~MyFoo(); +template <class T, typename Traits = DefaultRefCountedThreadSafeTraits<T> > +class RefCountedThreadSafe : public subtle::RefCountedThreadSafeBase { + public: + RefCountedThreadSafe() {} + + void AddRef() const { + subtle::RefCountedThreadSafeBase::AddRef(); + } + + void Release() const { + if (subtle::RefCountedThreadSafeBase::Release()) { + Traits::Destruct(static_cast<const T*>(this)); + } + } + + protected: + ~RefCountedThreadSafe() {} + + private: + friend struct DefaultRefCountedThreadSafeTraits<T>; + static void DeleteInternal(const T* x) { delete x; } + + DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafe); +}; + +// +// A thread-safe wrapper for some piece of data so we can place other +// things in scoped_refptrs<>. +// +template<typename T> +class RefCountedData + : public base::RefCountedThreadSafe< base::RefCountedData<T> > { + public: + RefCountedData() : data() {} + RefCountedData(const T& in_value) : data(in_value) {} + + T data; + + private: + friend class base::RefCountedThreadSafe<base::RefCountedData<T> >; + ~RefCountedData() {} +}; + +} // namespace base + +// +// A smart pointer class for reference counted objects. Use this class instead +// of calling AddRef and Release manually on a reference counted object to +// avoid common memory leaks caused by forgetting to Release an object +// reference. Sample usage: +// +// class MyFoo : public RefCounted<MyFoo> { +// ... +// }; +// +// void some_function() { +// scoped_refptr<MyFoo> foo = new MyFoo(); +// foo->Method(param); +// // |foo| is released when this function returns +// } +// +// void some_other_function() { +// scoped_refptr<MyFoo> foo = new MyFoo(); +// ... +// foo = NULL; // explicitly releases |foo| +// ... +// if (foo) +// foo->Method(param); +// } +// +// The above examples show how scoped_refptr<T> acts like a pointer to T. +// Given two scoped_refptr<T> classes, it is also possible to exchange +// references between the two objects, like so: +// +// { +// scoped_refptr<MyFoo> a = new MyFoo(); +// scoped_refptr<MyFoo> b; +// +// b.swap(a); +// // now, |b| references the MyFoo object, and |a| references NULL. +// } +// +// To make both |a| and |b| in the above example reference the same MyFoo +// object, simply use the assignment operator: +// +// { +// scoped_refptr<MyFoo> a = new MyFoo(); +// scoped_refptr<MyFoo> b; +// +// b = a; +// // now, |a| and |b| each own a reference to the same MyFoo object. +// } +// +template <class T> +class scoped_refptr { + public: + typedef T element_type; + + scoped_refptr() : ptr_(NULL) { + } + + scoped_refptr(T* p) : ptr_(p) { + if (ptr_) + AddRef(ptr_); + } + + // Copy constructor. + scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) { + if (ptr_) + AddRef(ptr_); + } + + // Copy conversion constructor. + template <typename U> + scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) { + if (ptr_) + AddRef(ptr_); + } + + // Move constructor. This is required in addition to the conversion + // constructor below in order for clang to warn about pessimizing moves. + scoped_refptr(scoped_refptr&& r) : ptr_(r.get()) { r.ptr_ = nullptr; } + + // Move conversion constructor. + template <typename U> + scoped_refptr(scoped_refptr<U>&& r) : ptr_(r.get()) { + r.ptr_ = nullptr; + } + + ~scoped_refptr() { + if (ptr_) + Release(ptr_); + } + + T* get() const { return ptr_; } + + T& operator*() const { + assert(ptr_ != NULL); + return *ptr_; + } + + T* operator->() const { + assert(ptr_ != NULL); + return ptr_; + } + + scoped_refptr<T>& operator=(T* p) { + // AddRef first so that self assignment should work + if (p) + AddRef(p); + T* old_ptr = ptr_; + ptr_ = p; + if (old_ptr) + Release(old_ptr); + return *this; + } + + scoped_refptr<T>& operator=(const scoped_refptr<T>& r) { + return *this = r.ptr_; + } + + template <typename U> + scoped_refptr<T>& operator=(const scoped_refptr<U>& r) { + return *this = r.get(); + } + + scoped_refptr<T>& operator=(scoped_refptr<T>&& r) { + scoped_refptr<T>(std::move(r)).swap(*this); + return *this; + } + + template <typename U> + scoped_refptr<T>& operator=(scoped_refptr<U>&& r) { + scoped_refptr<T>(std::move(r)).swap(*this); + return *this; + } + + void swap(T** pp) { + T* p = ptr_; + ptr_ = *pp; + *pp = p; + } + + void swap(scoped_refptr<T>& r) { + swap(&r.ptr_); + } + + private: + template <typename U> friend class scoped_refptr; + + // Allow scoped_refptr<T> 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 "refptr1 == refptr2" + // will compile but do the wrong thing (i.e., convert to Testable + // and then do the comparison). + typedef T* scoped_refptr::*Testable; + + public: + operator Testable() const { return ptr_ ? &scoped_refptr::ptr_ : nullptr; } + + template <typename U> + bool operator==(const scoped_refptr<U>& rhs) const { + return ptr_ == rhs.get(); + } + + template <typename U> + bool operator!=(const scoped_refptr<U>& rhs) const { + return !operator==(rhs); + } + + template <typename U> + bool operator<(const scoped_refptr<U>& rhs) const { + return ptr_ < rhs.get(); + } + + protected: + T* ptr_; + + private: + // Non-inline helpers to allow: + // class Opaque; + // extern template class scoped_refptr<Opaque>; + // Otherwise the compiler will complain that Opaque is an incomplete type. + static void AddRef(T* ptr); + static void Release(T* ptr); +}; + +template <typename T> +void scoped_refptr<T>::AddRef(T* ptr) { + ptr->AddRef(); +} + +template <typename T> +void scoped_refptr<T>::Release(T* ptr) { + ptr->Release(); +} + +// Handy utility for creating a scoped_refptr<T> out of a T* explicitly without +// having to retype all the template arguments +template <typename T> +scoped_refptr<T> make_scoped_refptr(T* t) { + return scoped_refptr<T>(t); +} + +// Temporary operator overloads to facilitate the transition. See +// https://crbug.com/110610. +template <typename T, typename U> +bool operator==(const scoped_refptr<T>& lhs, const U* rhs) { + return lhs.get() == rhs; +} + +template <typename T, typename U> +bool operator==(const T* lhs, const scoped_refptr<U>& rhs) { + return lhs == rhs.get(); +} + +template <typename T, typename U> +bool operator!=(const scoped_refptr<T>& lhs, const U* rhs) { + return !operator==(lhs, rhs); +} + +template <typename T, typename U> +bool operator!=(const T* lhs, const scoped_refptr<U>& rhs) { + return !operator==(lhs, rhs); +} + +template <typename T> +std::ostream& operator<<(std::ostream& out, const scoped_refptr<T>& p) { + return out << p.get(); +} + +#endif // BASE_MEMORY_REF_COUNTED_H_ |