ipc/chromium/src/base/ref_counted.h

Wed, 31 Dec 2014 06:09:35 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Wed, 31 Dec 2014 06:09:35 +0100
changeset 0
6474c204b198
permissions
-rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

michael@0 1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
michael@0 2 // Use of this source code is governed by a BSD-style license that can be
michael@0 3 // found in the LICENSE file.
michael@0 4
michael@0 5 #ifndef BASE_REF_COUNTED_H_
michael@0 6 #define BASE_REF_COUNTED_H_
michael@0 7
michael@0 8 #include "base/atomic_ref_count.h"
michael@0 9 #include "base/thread_collision_warner.h"
michael@0 10
michael@0 11 namespace base {
michael@0 12
michael@0 13 namespace subtle {
michael@0 14
michael@0 15 class RefCountedBase {
michael@0 16 protected:
michael@0 17 RefCountedBase();
michael@0 18 ~RefCountedBase();
michael@0 19
michael@0 20 void AddRef();
michael@0 21
michael@0 22 // Returns true if the object should self-delete.
michael@0 23 bool Release();
michael@0 24
michael@0 25 private:
michael@0 26 int ref_count_;
michael@0 27 #ifndef NDEBUG
michael@0 28 bool in_dtor_;
michael@0 29 #endif
michael@0 30
michael@0 31 DFAKE_MUTEX(add_release_)
michael@0 32
michael@0 33 DISALLOW_COPY_AND_ASSIGN(RefCountedBase);
michael@0 34 };
michael@0 35
michael@0 36 class RefCountedThreadSafeBase {
michael@0 37 protected:
michael@0 38 RefCountedThreadSafeBase();
michael@0 39 ~RefCountedThreadSafeBase();
michael@0 40
michael@0 41 void AddRef();
michael@0 42
michael@0 43 // Returns true if the object should self-delete.
michael@0 44 bool Release();
michael@0 45
michael@0 46 private:
michael@0 47 AtomicRefCount ref_count_;
michael@0 48 #ifndef NDEBUG
michael@0 49 bool in_dtor_;
michael@0 50 #endif
michael@0 51
michael@0 52 DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafeBase);
michael@0 53 };
michael@0 54
michael@0 55
michael@0 56
michael@0 57 } // namespace subtle
michael@0 58
michael@0 59 //
michael@0 60 // A base class for reference counted classes. Otherwise, known as a cheap
michael@0 61 // knock-off of WebKit's RefCounted<T> class. To use this guy just extend your
michael@0 62 // class from it like so:
michael@0 63 //
michael@0 64 // class MyFoo : public base::RefCounted<MyFoo> {
michael@0 65 // ...
michael@0 66 // };
michael@0 67 //
michael@0 68 template <class T>
michael@0 69 class RefCounted : public subtle::RefCountedBase {
michael@0 70 public:
michael@0 71 RefCounted() { }
michael@0 72 ~RefCounted() { }
michael@0 73
michael@0 74 void AddRef() {
michael@0 75 subtle::RefCountedBase::AddRef();
michael@0 76 }
michael@0 77
michael@0 78 void Release() {
michael@0 79 if (subtle::RefCountedBase::Release()) {
michael@0 80 delete static_cast<T*>(this);
michael@0 81 }
michael@0 82 }
michael@0 83
michael@0 84 private:
michael@0 85 DISALLOW_COPY_AND_ASSIGN(RefCounted<T>);
michael@0 86 };
michael@0 87
michael@0 88 //
michael@0 89 // A thread-safe variant of RefCounted<T>
michael@0 90 //
michael@0 91 // class MyFoo : public base::RefCountedThreadSafe<MyFoo> {
michael@0 92 // ...
michael@0 93 // };
michael@0 94 //
michael@0 95 template <class T>
michael@0 96 class RefCountedThreadSafe : public subtle::RefCountedThreadSafeBase {
michael@0 97 public:
michael@0 98 RefCountedThreadSafe() { }
michael@0 99 ~RefCountedThreadSafe() { }
michael@0 100
michael@0 101 void AddRef() {
michael@0 102 subtle::RefCountedThreadSafeBase::AddRef();
michael@0 103 }
michael@0 104
michael@0 105 void Release() {
michael@0 106 if (subtle::RefCountedThreadSafeBase::Release()) {
michael@0 107 delete static_cast<T*>(this);
michael@0 108 }
michael@0 109 }
michael@0 110
michael@0 111 private:
michael@0 112 DISALLOW_COPY_AND_ASSIGN(RefCountedThreadSafe<T>);
michael@0 113 };
michael@0 114
michael@0 115 //
michael@0 116 // A wrapper for some piece of data so we can place other things in
michael@0 117 // scoped_refptrs<>.
michael@0 118 //
michael@0 119 template<typename T>
michael@0 120 class RefCountedData : public base::RefCounted< base::RefCountedData<T> > {
michael@0 121 public:
michael@0 122 RefCountedData() : data() {}
michael@0 123 RefCountedData(const T& in_value) : data(in_value) {}
michael@0 124
michael@0 125 T data;
michael@0 126 };
michael@0 127
michael@0 128 } // namespace base
michael@0 129
michael@0 130 //
michael@0 131 // A smart pointer class for reference counted objects. Use this class instead
michael@0 132 // of calling AddRef and Release manually on a reference counted object to
michael@0 133 // avoid common memory leaks caused by forgetting to Release an object
michael@0 134 // reference. Sample usage:
michael@0 135 //
michael@0 136 // class MyFoo : public RefCounted<MyFoo> {
michael@0 137 // ...
michael@0 138 // };
michael@0 139 //
michael@0 140 // void some_function() {
michael@0 141 // scoped_refptr<MyFoo> foo = new MyFoo();
michael@0 142 // foo->Method(param);
michael@0 143 // // |foo| is released when this function returns
michael@0 144 // }
michael@0 145 //
michael@0 146 // void some_other_function() {
michael@0 147 // scoped_refptr<MyFoo> foo = new MyFoo();
michael@0 148 // ...
michael@0 149 // foo = NULL; // explicitly releases |foo|
michael@0 150 // ...
michael@0 151 // if (foo)
michael@0 152 // foo->Method(param);
michael@0 153 // }
michael@0 154 //
michael@0 155 // The above examples show how scoped_refptr<T> acts like a pointer to T.
michael@0 156 // Given two scoped_refptr<T> classes, it is also possible to exchange
michael@0 157 // references between the two objects, like so:
michael@0 158 //
michael@0 159 // {
michael@0 160 // scoped_refptr<MyFoo> a = new MyFoo();
michael@0 161 // scoped_refptr<MyFoo> b;
michael@0 162 //
michael@0 163 // b.swap(a);
michael@0 164 // // now, |b| references the MyFoo object, and |a| references NULL.
michael@0 165 // }
michael@0 166 //
michael@0 167 // To make both |a| and |b| in the above example reference the same MyFoo
michael@0 168 // object, simply use the assignment operator:
michael@0 169 //
michael@0 170 // {
michael@0 171 // scoped_refptr<MyFoo> a = new MyFoo();
michael@0 172 // scoped_refptr<MyFoo> b;
michael@0 173 //
michael@0 174 // b = a;
michael@0 175 // // now, |a| and |b| each own a reference to the same MyFoo object.
michael@0 176 // }
michael@0 177 //
michael@0 178 template <class T>
michael@0 179 class scoped_refptr {
michael@0 180 public:
michael@0 181 scoped_refptr() : ptr_(NULL) {
michael@0 182 }
michael@0 183
michael@0 184 scoped_refptr(T* p) : ptr_(p) {
michael@0 185 if (ptr_)
michael@0 186 ptr_->AddRef();
michael@0 187 }
michael@0 188
michael@0 189 scoped_refptr(const scoped_refptr<T>& r) : ptr_(r.ptr_) {
michael@0 190 if (ptr_)
michael@0 191 ptr_->AddRef();
michael@0 192 }
michael@0 193
michael@0 194 ~scoped_refptr() {
michael@0 195 if (ptr_)
michael@0 196 ptr_->Release();
michael@0 197 }
michael@0 198
michael@0 199 T* get() const { return ptr_; }
michael@0 200 operator T*() const { return ptr_; }
michael@0 201 T* operator->() const { return ptr_; }
michael@0 202
michael@0 203 scoped_refptr<T>& operator=(T* p) {
michael@0 204 // AddRef first so that self assignment should work
michael@0 205 if (p)
michael@0 206 p->AddRef();
michael@0 207 if (ptr_ )
michael@0 208 ptr_ ->Release();
michael@0 209 ptr_ = p;
michael@0 210 return *this;
michael@0 211 }
michael@0 212
michael@0 213 scoped_refptr<T>& operator=(const scoped_refptr<T>& r) {
michael@0 214 return *this = r.ptr_;
michael@0 215 }
michael@0 216
michael@0 217 void swap(T** pp) {
michael@0 218 T* p = ptr_;
michael@0 219 ptr_ = *pp;
michael@0 220 *pp = p;
michael@0 221 }
michael@0 222
michael@0 223 void swap(scoped_refptr<T>& r) {
michael@0 224 swap(&r.ptr_);
michael@0 225 }
michael@0 226
michael@0 227 protected:
michael@0 228 T* ptr_;
michael@0 229 };
michael@0 230
michael@0 231 #endif // BASE_REF_COUNTED_H_

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