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1 | |
2 /* | |
3 * Copyright 2006 The Android Open Source Project | |
4 * | |
5 * Use of this source code is governed by a BSD-style license that can be | |
6 * found in the LICENSE file. | |
7 */ | |
8 | |
9 | |
10 #ifndef SkThread_platform_DEFINED | |
11 #define SkThread_platform_DEFINED | |
12 | |
13 #if defined(SK_BUILD_FOR_ANDROID) | |
14 | |
15 #if !defined(SK_BUILD_FOR_ANDROID_FRAMEWORK) | |
16 | |
17 #include <stdint.h> | |
18 | |
19 /* Just use the GCC atomic intrinsics. They're supported by the NDK toolchain, | |
20 * have reasonable performance, and provide full memory barriers | |
21 */ | |
22 static inline __attribute__((always_inline)) int32_t sk_atomic_inc(int32_t *addr
) { | |
23 return __sync_fetch_and_add(addr, 1); | |
24 } | |
25 | |
26 static inline __attribute__((always_inline)) int32_t sk_atomic_add(int32_t *addr
, int32_t inc) { | |
27 return __sync_fetch_and_add(addr, inc); | |
28 } | |
29 | |
30 static inline __attribute__((always_inline)) int32_t sk_atomic_dec(int32_t *addr
) { | |
31 return __sync_fetch_and_add(addr, -1); | |
32 } | |
33 static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic
_dec() { } | |
34 | |
35 static inline __attribute__((always_inline)) int32_t sk_atomic_conditional_inc(i
nt32_t* addr) { | |
36 int32_t value = *addr; | |
37 | |
38 while (true) { | |
39 if (value == 0) { | |
40 return 0; | |
41 } | |
42 | |
43 int32_t before = __sync_val_compare_and_swap(addr, value, value + 1); | |
44 | |
45 if (before == value) { | |
46 return value; | |
47 } else { | |
48 value = before; | |
49 } | |
50 } | |
51 } | |
52 static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic
_conditional_inc() { } | |
53 | |
54 #else // SK_BUILD_FOR_ANDROID_FRAMEWORK | |
55 | |
56 /* The platform atomics operations are slightly more efficient than the | |
57 * GCC built-ins, so use them. | |
58 */ | |
59 #include <utils/Atomic.h> | |
60 | |
61 #define sk_atomic_inc(addr) android_atomic_inc(addr) | |
62 #define sk_atomic_add(addr, inc) android_atomic_add(inc, addr) | |
63 #define sk_atomic_dec(addr) android_atomic_dec(addr) | |
64 | |
65 static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic
_dec() { | |
66 //HACK: Android is actually using full memory barriers. | |
67 // Should this change, uncomment below. | |
68 //int dummy; | |
69 //android_atomic_aquire_store(0, &dummy); | |
70 } | |
71 static inline __attribute__((always_inline)) int32_t sk_atomic_conditional_inc(i
nt32_t* addr) { | |
72 while (true) { | |
73 int32_t value = *addr; | |
74 if (value == 0) { | |
75 return 0; | |
76 } | |
77 if (0 == android_atomic_release_cas(value, value + 1, addr)) { | |
78 return value; | |
79 } | |
80 } | |
81 } | |
82 static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic
_conditional_inc() { | |
83 //HACK: Android is actually using full memory barriers. | |
84 // Should this change, uncomment below. | |
85 //int dummy; | |
86 //android_atomic_aquire_store(0, &dummy); | |
87 } | |
88 | |
89 #endif // SK_BUILD_FOR_ANDROID_FRAMEWORK | |
90 | |
91 #else // !SK_BUILD_FOR_ANDROID | |
92 | |
93 /** Implemented by the porting layer, this function adds one to the int | |
94 specified by the address (in a thread-safe manner), and returns the | |
95 previous value. | |
96 No additional memory barrier is required. | |
97 This must act as a compiler barrier. | |
98 */ | |
99 SK_API int32_t sk_atomic_inc(int32_t* addr); | |
100 | |
101 /** Implemented by the porting layer, this function adds inc to the int | |
102 specified by the address (in a thread-safe manner), and returns the | |
103 previous value. | |
104 No additional memory barrier is required. | |
105 This must act as a compiler barrier. | |
106 */ | |
107 SK_API int32_t sk_atomic_add(int32_t* addr, int32_t inc); | |
108 | |
109 /** Implemented by the porting layer, this function subtracts one from the int | |
110 specified by the address (in a thread-safe manner), and returns the | |
111 previous value. | |
112 Expected to act as a release (SL/S) memory barrier and a compiler barrier. | |
113 */ | |
114 SK_API int32_t sk_atomic_dec(int32_t* addr); | |
115 /** If sk_atomic_dec does not act as an aquire (L/SL) barrier, this is expected | |
116 to act as an aquire (L/SL) memory barrier and as a compiler barrier. | |
117 */ | |
118 SK_API void sk_membar_aquire__after_atomic_dec(); | |
119 | |
120 /** Implemented by the porting layer, this function adds one to the int | |
121 specified by the address iff the int specified by the address is not zero | |
122 (in a thread-safe manner), and returns the previous value. | |
123 No additional memory barrier is required. | |
124 This must act as a compiler barrier. | |
125 */ | |
126 SK_API int32_t sk_atomic_conditional_inc(int32_t*); | |
127 /** If sk_atomic_conditional_inc does not act as an aquire (L/SL) barrier, this | |
128 is expected to act as an aquire (L/SL) memory barrier and as a compiler | |
129 barrier. | |
130 */ | |
131 SK_API void sk_membar_aquire__after_atomic_conditional_inc(); | |
132 | |
133 #endif // !SK_BUILD_FOR_ANDROID | |
134 | |
135 #ifdef SK_USE_POSIX_THREADS | |
136 | |
137 #include <pthread.h> | |
138 | |
139 // A SkBaseMutex is a POD structure that can be directly initialized | |
140 // at declaration time with SK_DECLARE_STATIC/GLOBAL_MUTEX. This avoids the | |
141 // generation of a static initializer in the final machine code (and | |
142 // a corresponding static finalizer). | |
143 // | |
144 struct SkBaseMutex { | |
145 void acquire() { pthread_mutex_lock(&fMutex); } | |
146 void release() { pthread_mutex_unlock(&fMutex); } | |
147 pthread_mutex_t fMutex; | |
148 }; | |
149 | |
150 // Using POD-style initialization prevents the generation of a static initialize
r | |
151 // and keeps the acquire() implementation small and fast. | |
152 #define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = { PTHREAD_MUT
EX_INITIALIZER } | |
153 | |
154 // Special case used when the static mutex must be available globally. | |
155 #define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name = { PTHREAD_MUTEX_INIT
IALIZER } | |
156 | |
157 // A normal mutex that requires to be initialized through normal C++ constructio
n, | |
158 // i.e. when it's a member of another class, or allocated on the heap. | |
159 class SK_API SkMutex : public SkBaseMutex, SkNoncopyable { | |
160 public: | |
161 SkMutex(); | |
162 ~SkMutex(); | |
163 }; | |
164 | |
165 #else // !SK_USE_POSIX_THREADS | |
166 | |
167 // In the generic case, SkBaseMutex and SkMutex are the same thing, and we | |
168 // can't easily get rid of static initializers. | |
169 // | |
170 class SK_API SkMutex : SkNoncopyable { | |
171 public: | |
172 SkMutex(); | |
173 ~SkMutex(); | |
174 | |
175 void acquire(); | |
176 void release(); | |
177 | |
178 private: | |
179 bool fIsGlobal; | |
180 enum { | |
181 kStorageIntCount = 64 | |
182 }; | |
183 uint32_t fStorage[kStorageIntCount]; | |
184 }; | |
185 | |
186 typedef SkMutex SkBaseMutex; | |
187 | |
188 #define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name | |
189 #define SK_DECLARE_GLOBAL_MUTEX(name) SkBaseMutex name | |
190 | |
191 #endif // !SK_USE_POSIX_THREADS | |
192 | |
193 | |
194 #endif | |
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