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Side by Side Diff: include/core/SkLazyPtr.h

Issue 1316123003: Style Change: SkNEW->new; SkDELETE->delete (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: 2015-08-26 (Wednesday) 15:59:00 EDT Created 5 years, 3 months ago
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1 /* 1 /*
2 * Copyright 2014 Google Inc. 2 * Copyright 2014 Google Inc.
3 * 3 *
4 * Use of this source code is governed by a BSD-style license that can be 4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file. 5 * found in the LICENSE file.
6 */ 6 */
7 7
8 #ifndef SkLazyPtr_DEFINED 8 #ifndef SkLazyPtr_DEFINED
9 #define SkLazyPtr_DEFINED 9 #define SkLazyPtr_DEFINED
10 10
11 /** Declare a lazily-chosen static pointer (or array of pointers) of type T. 11 /** Declare a lazily-chosen static pointer (or array of pointers) of type T.
12 * 12 *
13 * Example usage: 13 * Example usage:
14 * 14 *
15 * Foo* GetSingletonFoo() { 15 * Foo* GetSingletonFoo() {
16 * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton); // Created with SkNEW, dest royed with SkDELETE. 16 * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton); // Created with new, destro yed with delete.
17 * return singleton.get(); 17 * return singleton.get();
18 * } 18 * }
19 * 19 *
20 * These macros take an optional T* (*Create)() and void (*Destroy)(T*) at the end. 20 * These macros take an optional T* (*Create)() and void (*Destroy)(T*) at the end.
21 * If not given, we'll use SkNEW and SkDELETE. 21 * If not given, we'll use new and delete.
22 * These options are most useful when T doesn't have a public constructor or de structor. 22 * These options are most useful when T doesn't have a public constructor or de structor.
23 * Create comes first, so you may use a custom Create with a default Destroy, b ut not vice versa. 23 * Create comes first, so you may use a custom Create with a default Destroy, b ut not vice versa.
24 * 24 *
25 * Foo* CustomCreate() { return ...; } 25 * Foo* CustomCreate() { return ...; }
26 * void CustomDestroy(Foo* ptr) { ... } 26 * void CustomDestroy(Foo* ptr) { ... }
27 * Foo* GetSingletonFooWithCustomCleanup() { 27 * Foo* GetSingletonFooWithCustomCleanup() {
28 * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CustomCreate, CustomDestroy); 28 * SK_DECLARE_STATIC_LAZY_PTR(Foo, singleton, CustomCreate, CustomDestroy);
29 * return singleton.get(); 29 * return singleton.get();
30 * } 30 * }
31 * 31 *
(...skipping 47 matching lines...) Expand 10 before | Expand all | Expand 10 after
79 SkASSERT(!prev); 79 SkASSERT(!prev);
80 return ptr; 80 return ptr;
81 } else { 81 } else {
82 Destroy(ptr); 82 Destroy(ptr);
83 // We need an acquire barrier before returning prev. The compare_exchan ge provided it. 83 // We need an acquire barrier before returning prev. The compare_exchan ge provided it.
84 SkASSERT(prev); 84 SkASSERT(prev);
85 return prev; 85 return prev;
86 } 86 }
87 } 87 }
88 88
89 template <typename T> T* sk_new() { return SkNEW(T); } 89 template <typename T>
90 template <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); } 90 T* sk_new() {
91 return new T;
92 }
93 template <typename T>
94 void sk_delete(T* ptr) {
95 delete ptr;
96 }
91 97
92 // We're basing these implementations here on this article: 98 // We're basing these implementations here on this article:
93 // http://preshing.com/20140709/the-purpose-of-memory_order_consume-in-cpp11/ 99 // http://preshing.com/20140709/the-purpose-of-memory_order_consume-in-cpp11/
94 // 100 //
95 // Because the users of SkLazyPtr and SkLazyPtrArray will read the pointers 101 // Because the users of SkLazyPtr and SkLazyPtrArray will read the pointers
96 // _through_ our atomically set pointer, there is a data dependency between our 102 // _through_ our atomically set pointer, there is a data dependency between our
97 // atomic and the guarded data, and so we only need writer-releases / 103 // atomic and the guarded data, and so we only need writer-releases /
98 // reader-consumes memory pairing rather than the more general write-releases / 104 // reader-consumes memory pairing rather than the more general write-releases /
99 // reader-acquires convention. 105 // reader-acquires convention.
100 // 106 //
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121 // If fPtr has already been filled, we need a consume barrier when loadi ng it. 127 // If fPtr has already been filled, we need a consume barrier when loadi ng it.
122 // If not, we need a release barrier when setting it. try_cas will do t hat. 128 // If not, we need a release barrier when setting it. try_cas will do t hat.
123 T* ptr = consume_load(&fPtr); 129 T* ptr = consume_load(&fPtr);
124 return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create()); 130 return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create());
125 } 131 }
126 132
127 private: 133 private:
128 T* fPtr; 134 T* fPtr;
129 }; 135 };
130 136
131 template <typename T> T* sk_new_arg(int i) { return SkNEW_ARGS(T, (i)); } 137 template <typename T>
138 T* sk_new_arg(int i) {
139 return new T(i);
140 }
132 141
133 // This has no constructor and must be zero-initalized (the macro above does thi s). 142 // This has no constructor and must be zero-initalized (the macro above does thi s).
134 template <typename T, int N, T* (*Create)(int) = sk_new_arg<T>, void (*Destroy)( T*) = sk_delete<T> > 143 template <typename T, int N, T* (*Create)(int) = sk_new_arg<T>, void (*Destroy)( T*) = sk_delete<T> >
135 class SkStaticLazyPtrArray { 144 class SkStaticLazyPtrArray {
136 public: 145 public:
137 T* operator[](int i) { 146 T* operator[](int i) {
138 SkASSERT(i >= 0 && i < N); 147 SkASSERT(i >= 0 && i < N);
139 // If fPtr has already been filled, we need an consume barrier when load ing it. 148 // If fPtr has already been filled, we need an consume barrier when load ing it.
140 // If not, we need a release barrier when setting it. try_cas will do t hat. 149 // If not, we need a release barrier when setting it. try_cas will do t hat.
141 T* ptr = consume_load(&fArray[i]); 150 T* ptr = consume_load(&fArray[i]);
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155 // - get() calls SkNew(T) to create the pointer; 164 // - get() calls SkNew(T) to create the pointer;
156 // - get(functor) calls functor to create the pointer. 165 // - get(functor) calls functor to create the pointer.
157 template <typename T, void (*Destroy)(T*) = Private::sk_delete<T> > 166 template <typename T, void (*Destroy)(T*) = Private::sk_delete<T> >
158 class SkLazyPtr : SkNoncopyable { 167 class SkLazyPtr : SkNoncopyable {
159 public: 168 public:
160 SkLazyPtr() : fPtr(NULL) {} 169 SkLazyPtr() : fPtr(NULL) {}
161 ~SkLazyPtr() { if (fPtr) { Destroy((T*)fPtr); } } 170 ~SkLazyPtr() { if (fPtr) { Destroy((T*)fPtr); } }
162 171
163 T* get() const { 172 T* get() const {
164 T* ptr = Private::consume_load(&fPtr); 173 T* ptr = Private::consume_load(&fPtr);
165 return ptr ? ptr : Private::try_cas<T*, Destroy>(&fPtr, SkNEW(T)); 174 return ptr ? ptr : Private::try_cas<T*, Destroy>(&fPtr, new T);
166 } 175 }
167 176
168 template <typename Create> 177 template <typename Create>
169 T* get(const Create& create) const { 178 T* get(const Create& create) const {
170 T* ptr = Private::consume_load(&fPtr); 179 T* ptr = Private::consume_load(&fPtr);
171 return ptr ? ptr : Private::try_cas<T*, Destroy>(&fPtr, create()); 180 return ptr ? ptr : Private::try_cas<T*, Destroy>(&fPtr, create());
172 } 181 }
173 182
174 private: 183 private:
175 mutable T* fPtr; 184 mutable T* fPtr;
176 }; 185 };
177 186
178 187
179 #endif//SkLazyPtr_DEFINED 188 #endif//SkLazyPtr_DEFINED
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