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authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /security/sandbox/chromium/base/memory/ref_counted.h
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
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Add m-esr52 at 52.6.0
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diff --git a/security/sandbox/chromium/base/memory/ref_counted.h b/security/sandbox/chromium/base/memory/ref_counted.h
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+// 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_