The Tor Browser / file revision

 /*

  * Copyright 2014 Google Inc.

  *

  * Use of this source code is governed by a BSD-style license that can be

  * found in the LICENSE file.

  */

 #ifndef SkDynamicAnnotations_DEFINED

 #define SkDynamicAnnotations_DEFINED

 // This file contains macros used to send out-of-band signals to dynamic instrumentation systems,

 // namely thread sanitizer.  This is a cut-down version of the full dynamic_annotations library with

 // only the features used by Skia.

 // We check the same define to know to enable the annotations, but prefix all our macros with SK_.

 #if DYNAMIC_ANNOTATIONS_ENABLED

 extern "C" {

 // TSAN provides these hooks.

 void AnnotateIgnoreReadsBegin(const char* file, int line);

 void AnnotateIgnoreReadsEnd(const char* file, int line);

 }  // extern "C"

 // SK_ANNOTATE_UNPROTECTED_READ can wrap any variable read to tell TSAN to ignore that it appears to

 // be a racy read.  This should be used only when we can make an external guarantee that though this

 // particular read is racy, it is being used as part of a mechanism which is thread safe.  Examples:

 //   - the first check in double-checked locking;

 //   - checking if a ref count is equal to 1.

 // Note that in both these cases, we must still add terrifyingly subtle memory barriers to provide

 // that overall thread safety guarantee.  Using this macro to shut TSAN up without providing such an

 // external guarantee is pretty much never correct.

 template <typename T>

 inline T SK_ANNOTATE_UNPROTECTED_READ(const volatile T& x) {

     AnnotateIgnoreReadsBegin(__FILE__, __LINE__);

     T read = x;

     AnnotateIgnoreReadsEnd(__FILE__, __LINE__);

     return read;

 }

 #else  // !DYNAMIC_ANNOTATIONS_ENABLED

 #define SK_ANNOTATE_UNPROTECTED_READ(x) (x)

 #endif

 #endif//SkDynamicAnnotations_DEFINED