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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 SkDynamicAnnotations_DEFINED | 8 #ifndef SkDynamicAnnotations_DEFINED |
| 9 #define SkDynamicAnnotations_DEFINED | 9 #define SkDynamicAnnotations_DEFINED |
| 10 | 10 |
| 11 // This file contains macros used to send out-of-band signals to dynamic instrum
entation systems, | 11 // This file contains macros used to send out-of-band signals to dynamic instrum
entation systems, |
| 12 // namely thread sanitizer. This is a cut-down version of the full dynamic_anno
tations library with | 12 // namely thread sanitizer. This is a cut-down version of the full dynamic_anno
tations library with |
| 13 // only the features used by Skia. | 13 // only the features used by Skia. |
| 14 | 14 |
| 15 // We check the same define to know to enable the annotations, but prefix all ou
r macros with SK_. | 15 // We check the same define to know to enable the annotations, but prefix all ou
r macros with SK_. |
| 16 #if DYNAMIC_ANNOTATIONS_ENABLED | 16 #if DYNAMIC_ANNOTATIONS_ENABLED |
| 17 | 17 |
| 18 extern "C" { | 18 extern "C" { |
| 19 // TSAN provides these hooks. | 19 // TSAN provides these hooks. |
| 20 void AnnotateIgnoreReadsBegin(const char* file, int line); | 20 void AnnotateIgnoreReadsBegin(const char* file, int line); |
| 21 void AnnotateIgnoreReadsEnd(const char* file, int line); | 21 void AnnotateIgnoreReadsEnd(const char* file, int line); |
| 22 void AnnotateBenignRaceSized(const char* file, int line, | |
| 23 const void* addr, long size, const char* desc); | |
| 24 } // extern "C" | 22 } // extern "C" |
| 25 | 23 |
| 26 // SK_ANNOTATE_UNPROTECTED_READ can wrap any variable read to tell TSAN to ignor
e that it appears to | 24 // SK_ANNOTATE_UNPROTECTED_READ can wrap any variable read to tell TSAN to ignor
e that it appears to |
| 27 // be a racy read. This should be used only when we can make an external guaran
tee that though this | 25 // be a racy read. This should be used only when we can make an external guaran
tee that though this |
| 28 // particular read is racy, it is being used as part of a mechanism which is thr
ead safe. Examples: | 26 // particular read is racy, it is being used as part of a mechanism which is thr
ead safe. Examples: |
| 29 // - the first check in double-checked locking; | 27 // - the first check in double-checked locking; |
| 30 // - checking if a ref count is equal to 1. | 28 // - checking if a ref count is equal to 1. |
| 31 // Note that in both these cases, we must still add terrifyingly subtle memory b
arriers to provide | 29 // Note that in both these cases, we must still add terrifyingly subtle memory b
arriers to provide |
| 32 // that overall thread safety guarantee. Using this macro to shut TSAN up witho
ut providing such an | 30 // that overall thread safety guarantee. Using this macro to shut TSAN up witho
ut providing such an |
| 33 // external guarantee is pretty much never correct. | 31 // external guarantee is pretty much never correct. |
| 34 template <typename T> | 32 template <typename T> |
| 35 inline T SK_ANNOTATE_UNPROTECTED_READ(const volatile T& x) { | 33 inline T SK_ANNOTATE_UNPROTECTED_READ(const volatile T& x) { |
| 36 AnnotateIgnoreReadsBegin(__FILE__, __LINE__); | 34 AnnotateIgnoreReadsBegin(__FILE__, __LINE__); |
| 37 T read = x; | 35 T read = x; |
| 38 AnnotateIgnoreReadsEnd(__FILE__, __LINE__); | 36 AnnotateIgnoreReadsEnd(__FILE__, __LINE__); |
| 39 return read; | 37 return read; |
| 40 } | 38 } |
| 41 | 39 |
| 42 // Ignore racy reads and racy writes to this pointer, indefinitely. | |
| 43 // If at all possible, use the more precise SK_ANNOTATE_UNPROTECTED_READ. | |
| 44 template <typename T> | |
| 45 void SK_ANNOTATE_BENIGN_RACE(T* ptr) { | |
| 46 AnnotateBenignRaceSized(__FILE__, __LINE__, ptr, sizeof(*ptr), "SK_ANNOTATE_
BENIGN_RACE"); | |
| 47 } | |
| 48 | |
| 49 #else // !DYNAMIC_ANNOTATIONS_ENABLED | 40 #else // !DYNAMIC_ANNOTATIONS_ENABLED |
| 50 | 41 |
| 51 #define SK_ANNOTATE_UNPROTECTED_READ(x) (x) | 42 #define SK_ANNOTATE_UNPROTECTED_READ(x) (x) |
| 52 #define SK_ANNOTATE_BENIGN_RACE(ptr) | |
| 53 | 43 |
| 54 #endif | 44 #endif |
| 55 | 45 |
| 56 // Can be used to wrap values that are intentionally racy, usually small mutable
cached values, e.g. | |
| 57 // - SkMatrix type mask | |
| 58 // - SkPathRef bounds | |
| 59 // - SkPixelRef genIDs | |
| 60 template <typename T> | |
| 61 class SkTRacy { | |
| 62 public: | |
| 63 SkTRacy() { SK_ANNOTATE_BENIGN_RACE(&fVal); } | |
| 64 | |
| 65 operator const T&() const { | |
| 66 return fVal; | |
| 67 } | |
| 68 | |
| 69 SkTRacy& operator=(const T& val) { | |
| 70 fVal = val; | |
| 71 return *this; | |
| 72 } | |
| 73 | |
| 74 const T* get() const { return &fVal; } | |
| 75 T* get() { return &fVal; } | |
| 76 | |
| 77 const T* operator->() const { return &fVal; } | |
| 78 T* operator->() { return &fVal; } | |
| 79 | |
| 80 private: | |
| 81 T fVal; | |
| 82 }; | |
| 83 | |
| 84 #endif//SkDynamicAnnotations_DEFINED | 46 #endif//SkDynamicAnnotations_DEFINED |
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