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comparison: gfx/skia/trunk/include/core/SkDynamicAnnotations.h
gfx/skia/trunk/include/core/SkDynamicAnnotations.h
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:939599a4325d |
|---|---|
| 1 /* | |
| 2 * Copyright 2014 Google Inc. | |
| 3 * | |
| 4 * Use of this source code is governed by a BSD-style license that can be | |
| 5 * found in the LICENSE file. | |
| 6 */ | |
| 7 | |
| 8 #ifndef SkDynamicAnnotations_DEFINED | |
| 9 #define SkDynamicAnnotations_DEFINED | |
| 10 | |
| 11 // This file contains macros used to send out-of-band signals to dynamic instrumentation systems, | |
| 12 // namely thread sanitizer. This is a cut-down version of the full dynamic_annotations library with | |
| 13 // only the features used by Skia. | |
| 14 | |
| 15 // We check the same define to know to enable the annotations, but prefix all our macros with SK_. | |
| 16 #if DYNAMIC_ANNOTATIONS_ENABLED | |
| 17 | |
| 18 extern "C" { | |
| 19 // TSAN provides these hooks. | |
| 20 void AnnotateIgnoreReadsBegin(const char* file, int line); | |
| 21 void AnnotateIgnoreReadsEnd(const char* file, int line); | |
| 22 } // extern "C" | |
| 23 | |
| 24 // SK_ANNOTATE_UNPROTECTED_READ can wrap any variable read to tell TSAN to ignore that it appears to | |
| 25 // be a racy read. This should be used only when we can make an external guarantee that though this | |
| 26 // particular read is racy, it is being used as part of a mechanism which is thread safe. Examples: | |
| 27 // - the first check in double-checked locking; | |
| 28 // - checking if a ref count is equal to 1. | |
| 29 // Note that in both these cases, we must still add terrifyingly subtle memory barriers to provide | |
| 30 // that overall thread safety guarantee. Using this macro to shut TSAN up without providing such an | |
| 31 // external guarantee is pretty much never correct. | |
| 32 template <typename T> | |
| 33 inline T SK_ANNOTATE_UNPROTECTED_READ(const volatile T& x) { | |
| 34 AnnotateIgnoreReadsBegin(__FILE__, __LINE__); | |
| 35 T read = x; | |
| 36 AnnotateIgnoreReadsEnd(__FILE__, __LINE__); | |
| 37 return read; | |
| 38 } | |
| 39 | |
| 40 #else // !DYNAMIC_ANNOTATIONS_ENABLED | |
| 41 | |
| 42 #define SK_ANNOTATE_UNPROTECTED_READ(x) (x) | |
| 43 | |
| 44 #endif | |
| 45 | |
| 46 #endif//SkDynamicAnnotations_DEFINED |
