1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/security/sandbox/chromium/base/memory/ref_counted.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,301 @@
1.4 +// Copyright (c) 2012 The Chromium Authors. All rights reserved.
1.5 +// Use of this source code is governed by a BSD-style license that can be
1.6 +// found in the LICENSE file.
1.7 +
1.8 +#ifndef BASE_MEMORY_REF_COUNTED_H_
1.9 +#define BASE_MEMORY_REF_COUNTED_H_
1.10 +
1.11 +#include <cassert>
1.12 +
1.13 +#include "base/atomic_ref_count.h"
1.14 +#include "base/base_export.h"
1.15 +#include "base/compiler_specific.h"
1.16 +#include "base/threading/thread_collision_warner.h"
1.17 +
1.18 +namespace base {
1.19 +
1.20 +namespace subtle {
1.21 +
1.22 +class BASE_EXPORT RefCountedBase {
1.23 + public:
1.24 + bool HasOneRef() const { return ref_count_ == 1; }
1.25 +
1.26 + protected:
1.27 + RefCountedBase();
1.28 + ~RefCountedBase();
1.29 +
1.30 + void AddRef() const;
1.31 +
1.32 + // Returns true if the object should self-delete.
1.33 + bool Release() const;
1.34 +
1.35 + private:
1.36 + mutable int ref_count_;
1.37 +#ifndef NDEBUG
1.38 + mutable bool in_dtor_;
1.39 +#endif
1.40 +
1.41 + DFAKE_MUTEX(add_release_);
1.42 +
1.43 + DISALLOW_COPY_AND_ASSIGN(RefCountedBase);
1.44 +};
1.45 +
1.46 +class BASE_EXPORT RefCountedThreadSafeBase {
1.47 + public:
1.48 + bool HasOneRef() const;
1.49 +
1.50 + protected:
1.51 + RefCountedThreadSafeBase();
1.52 + ~RefCountedThreadSafeBase();
1.53 +
1.54 + void AddRef() const;
1.55 +
1.56 + // Returns true if the object should self-delete.
1.57 + bool Release() const;
1.58 +
1.59 + private:
1.60 + mutable AtomicRefCount ref_count_;
1.61 +#ifndef NDEBUG
1.62 + mutable bool in_dtor_;
1.63 +#endif
1.64 +
1.65 + DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase);
1.66 +};
1.67 +
1.68 +} // namespace subtle
1.69 +
1.70 +//
1.71 +// A base class for reference counted classes. Otherwise, known as a cheap
1.72 +// knock-off of WebKit's RefCounted<T> class. To use this guy just extend your
1.73 +// class from it like so:
1.74 +//
1.75 +// class MyFoo : public base::RefCounted<MyFoo> {
1.76 +// ...
1.77 +// private:
1.78 +// friend class base::RefCounted<MyFoo>;
1.79 +// ~MyFoo();
1.80 +// };
1.81 +//
1.82 +// You should always make your destructor private, to avoid any code deleting
1.83 +// the object accidently while there are references to it.
1.84 +template <class T>
1.85 +class RefCounted : public subtle::RefCountedBase {
1.86 + public:
1.87 + RefCounted() {}
1.88 +
1.89 + void AddRef() const {
1.90 + subtle::RefCountedBase::AddRef();
1.91 + }
1.92 +
1.93 + void Release() const {
1.94 + if (subtle::RefCountedBase::Release()) {
1.95 + delete static_cast<const T*>(this);
1.96 + }
1.97 + }
1.98 +
1.99 + protected:
1.100 + ~RefCounted() {}
1.101 +
1.102 + private:
1.103 + DISALLOW_COPY_AND_ASSIGN(RefCounted<T>);
1.104 +};
1.105 +
1.106 +// Forward declaration.
1.107 +template <class T, typename Traits> class RefCountedThreadSafe;
1.108 +
1.109 +// Default traits for RefCountedThreadSafe<T>. Deletes the object when its ref
1.110 +// count reaches 0. Overload to delete it on a different thread etc.
1.111 +template<typename T>
1.112 +struct DefaultRefCountedThreadSafeTraits {
1.113 + static void Destruct(const T* x) {
1.114 + // Delete through RefCountedThreadSafe to make child classes only need to be
1.115 + // friend with RefCountedThreadSafe instead of this struct, which is an
1.116 + // implementation detail.
1.117 + RefCountedThreadSafe<T,
1.118 + DefaultRefCountedThreadSafeTraits>::DeleteInternal(x);
1.119 + }
1.120 +};
1.121 +
1.122 +//
1.123 +// A thread-safe variant of RefCounted<T>
1.124 +//
1.125 +// class MyFoo : public base::RefCountedThreadSafe<MyFoo> {
1.126 +// ...
1.127 +// };
1.128 +//
1.129 +// If you're using the default trait, then you should add compile time
1.130 +// asserts that no one else is deleting your object. i.e.
1.131 +// private:
1.132 +// friend class base::RefCountedThreadSafe<MyFoo>;
1.133 +// ~MyFoo();
1.134 +template <class T, typename Traits = DefaultRefCountedThreadSafeTraits<T> >
1.135 +class RefCountedThreadSafe : public subtle::RefCountedThreadSafeBase {
1.136 + public:
1.137 + RefCountedThreadSafe() {}
1.138 +
1.139 + void AddRef() const {
1.140 + subtle::RefCountedThreadSafeBase::AddRef();
1.141 + }
1.142 +
1.143 + void Release() const {
1.144 + if (subtle::RefCountedThreadSafeBase::Release()) {
1.145 + Traits::Destruct(static_cast<const T*>(this));
1.146 + }
1.147 + }
1.148 +
1.149 + protected:
1.150 + ~RefCountedThreadSafe() {}
1.151 +
1.152 + private:
1.153 + friend struct DefaultRefCountedThreadSafeTraits<T>;
1.154 + static void DeleteInternal(const T* x) { delete x; }
1.155 +
1.156 + DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafe);
1.157 +};
1.158 +
1.159 +//
1.160 +// A thread-safe wrapper for some piece of data so we can place other
1.161 +// things in scoped_refptrs<>.
1.162 +//
1.163 +template<typename T>
1.164 +class RefCountedData
1.165 + : public base::RefCountedThreadSafe< base::RefCountedData<T> > {
1.166 + public:
1.167 + RefCountedData() : data() {}
1.168 + RefCountedData(const T& in_value) : data(in_value) {}
1.169 +
1.170 + T data;
1.171 +
1.172 + private:
1.173 + friend class base::RefCountedThreadSafe<base::RefCountedData<T> >;
1.174 + ~RefCountedData() {}
1.175 +};
1.176 +
1.177 +} // namespace base
1.178 +
1.179 +//
1.180 +// A smart pointer class for reference counted objects. Use this class instead
1.181 +// of calling AddRef and Release manually on a reference counted object to
1.182 +// avoid common memory leaks caused by forgetting to Release an object
1.183 +// reference. Sample usage:
1.184 +//
1.185 +// class MyFoo : public RefCounted<MyFoo> {
1.186 +// ...
1.187 +// };
1.188 +//
1.189 +// void some_function() {
1.190 +// scoped_refptr<MyFoo> foo = new MyFoo();
1.191 +// foo->Method(param);
1.192 +// // |foo| is released when this function returns
1.193 +// }
1.194 +//
1.195 +// void some_other_function() {
1.196 +// scoped_refptr<MyFoo> foo = new MyFoo();
1.197 +// ...
1.198 +// foo = NULL; // explicitly releases |foo|
1.199 +// ...
1.200 +// if (foo)
1.201 +// foo->Method(param);
1.202 +// }
1.203 +//
1.204 +// The above examples show how scoped_refptr<T> acts like a pointer to T.
1.205 +// Given two scoped_refptr<T> classes, it is also possible to exchange
1.206 +// references between the two objects, like so:
1.207 +//
1.208 +// {
1.209 +// scoped_refptr<MyFoo> a = new MyFoo();
1.210 +// scoped_refptr<MyFoo> b;
1.211 +//
1.212 +// b.swap(a);
1.213 +// // now, |b| references the MyFoo object, and |a| references NULL.
1.214 +// }
1.215 +//
1.216 +// To make both |a| and |b| in the above example reference the same MyFoo
1.217 +// object, simply use the assignment operator:
1.218 +//
1.219 +// {
1.220 +// scoped_refptr<MyFoo> a = new MyFoo();
1.221 +// scoped_refptr<MyFoo> b;
1.222 +//
1.223 +// b = a;
1.224 +// // now, |a| and |b| each own a reference to the same MyFoo object.
1.225 +// }
1.226 +//
1.227 +template <class T>
1.228 +class scoped_refptr {
1.229 + public:
1.230 + typedef T element_type;
1.231 +
1.232 + scoped_refptr() : ptr_(NULL) {
1.233 + }
1.234 +
1.235 + scoped_refptr(T* p) : ptr_(p) {
1.236 + if (ptr_)
1.237 + ptr_->AddRef();
1.238 + }
1.239 +
1.240 + scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
1.241 + if (ptr_)
1.242 + ptr_->AddRef();
1.243 + }
1.244 +
1.245 + template <typename U>
1.246 + scoped_refptr(const scoped_refptr<U>& r) : ptr_(r.get()) {
1.247 + if (ptr_)
1.248 + ptr_->AddRef();
1.249 + }
1.250 +
1.251 + ~scoped_refptr() {
1.252 + if (ptr_)
1.253 + ptr_->Release();
1.254 + }
1.255 +
1.256 + T* get() const { return ptr_; }
1.257 + operator T*() const { return ptr_; }
1.258 + T* operator->() const {
1.259 + assert(ptr_ != NULL);
1.260 + return ptr_;
1.261 + }
1.262 +
1.263 + scoped_refptr<T>& operator=(T* p) {
1.264 + // AddRef first so that self assignment should work
1.265 + if (p)
1.266 + p->AddRef();
1.267 + T* old_ptr = ptr_;
1.268 + ptr_ = p;
1.269 + if (old_ptr)
1.270 + old_ptr->Release();
1.271 + return *this;
1.272 + }
1.273 +
1.274 + scoped_refptr<T>& operator=(const scoped_refptr<T>& r) {
1.275 + return *this = r.ptr_;
1.276 + }
1.277 +
1.278 + template <typename U>
1.279 + scoped_refptr<T>& operator=(const scoped_refptr<U>& r) {
1.280 + return *this = r.get();
1.281 + }
1.282 +
1.283 + void swap(T** pp) {
1.284 + T* p = ptr_;
1.285 + ptr_ = *pp;
1.286 + *pp = p;
1.287 + }
1.288 +
1.289 + void swap(scoped_refptr<T>& r) {
1.290 + swap(&r.ptr_);
1.291 + }
1.292 +
1.293 + protected:
1.294 + T* ptr_;
1.295 +};
1.296 +
1.297 +// Handy utility for creating a scoped_refptr<T> out of a T* explicitly without
1.298 +// having to retype all the template arguments
1.299 +template <typename T>
1.300 +scoped_refptr<T> make_scoped_refptr(T* t) {
1.301 + return scoped_refptr<T>(t);
1.302 +}
1.303 +
1.304 +#endif // BASE_MEMORY_REF_COUNTED_H_
