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 */
sk_atomic_inc(int32_t * addr)22 static inline __attribute__((always_inline)) int32_t sk_atomic_inc(int32_t *addr) {
23 return __sync_fetch_and_add(addr, 1);
24 }
25
sk_atomic_add(int32_t * addr,int32_t inc)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
sk_atomic_dec(int32_t * addr)30 static inline __attribute__((always_inline)) int32_t sk_atomic_dec(int32_t *addr) {
31 return __sync_fetch_and_add(addr, -1);
32 }
sk_membar_aquire__after_atomic_dec()33 static inline __attribute__((always_inline)) void sk_membar_aquire__after_atomic_dec() { }
34
sk_atomic_conditional_inc(int32_t * addr)35 static inline __attribute__((always_inline)) int32_t sk_atomic_conditional_inc(int32_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 }
sk_membar_aquire__after_atomic_conditional_inc()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 <cutils/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
sk_membar_aquire__after_atomic_dec()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 }
sk_atomic_conditional_inc(int32_t * addr)71 static inline __attribute__((always_inline)) int32_t sk_atomic_conditional_inc(int32_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 }
sk_membar_aquire__after_atomic_conditional_inc()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 {
acquireSkBaseMutex145 void acquire() { pthread_mutex_lock(&fMutex); }
releaseSkBaseMutex146 void release() { pthread_mutex_unlock(&fMutex); }
147 pthread_mutex_t fMutex;
148 };
149
150 // Using POD-style initialization prevents the generation of a static initializer
151 // and keeps the acquire() implementation small and fast.
152 #define SK_DECLARE_STATIC_MUTEX(name) static SkBaseMutex name = { PTHREAD_MUTEX_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_INITIALIZER }
156
157 // A normal mutex that requires to be initialized through normal C++ construction,
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
195