0a62ad734c
Reason for revert: http://build.chromium.org/p/client.skia/builders/Test-Ubuntu13.10-GCE-NoGPU-x86_64-Release-TSAN/builds/1557/steps/dm/logs/stdio Original issue's description: > I cannot remember what the race here actually was. > > Removing SkTRacy will show us, or perhaps show us we already fixed the race. > > BUG=chromium:437511 > > No public API changes. > TBR=reed@google.com > > Committed: https://skia.googlesource.com/skia/+/71409c83e69b387b3c5d567197d0421c36baf68d TBR=bungeman@google.com,mtklein@chromium.org NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true BUG=chromium:437511 Review URL: https://codereview.chromium.org/923543003
89 lines
3.1 KiB
C++
89 lines
3.1 KiB
C++
/*
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* Copyright 2014 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkDynamicAnnotations_DEFINED
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#define SkDynamicAnnotations_DEFINED
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// Make sure we see anything set via SkUserConfig.h (e.g. DYNAMIC_ANNOTATIONS_ENABLED).
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#include "SkTypes.h"
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// This file contains macros used to send out-of-band signals to dynamic instrumentation systems,
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// namely thread sanitizer. This is a cut-down version of the full dynamic_annotations library with
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// only the features used by Skia.
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#if DYNAMIC_ANNOTATIONS_ENABLED
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extern "C" {
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// TSAN provides these hooks.
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void AnnotateIgnoreReadsBegin(const char* file, int line);
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void AnnotateIgnoreReadsEnd(const char* file, int line);
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void AnnotateIgnoreWritesBegin(const char* file, int line);
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void AnnotateIgnoreWritesEnd(const char* file, int line);
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void AnnotateBenignRaceSized(const char* file, int line,
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const volatile void* addr, long size, const char* desc);
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} // extern "C"
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// SK_ANNOTATE_UNPROTECTED_READ can wrap any variable read to tell TSAN to ignore that it appears to
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// be a racy read. This should be used only when we can make an external guarantee that though this
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// particular read is racy, it is being used as part of a mechanism which is thread safe. Examples:
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// - the first check in double-checked locking;
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// - checking if a ref count is equal to 1.
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// Note that in both these cases, we must still add terrifyingly subtle memory barriers to provide
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// that overall thread safety guarantee. Using this macro to shut TSAN up without providing such an
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// external guarantee is pretty much never correct.
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template <typename T>
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inline T SK_ANNOTATE_UNPROTECTED_READ(const volatile T& x) {
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AnnotateIgnoreReadsBegin(__FILE__, __LINE__);
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T read = x;
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AnnotateIgnoreReadsEnd(__FILE__, __LINE__);
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return read;
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}
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// Like SK_ANNOTATE_UNPROTECTED_READ, but for writes.
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template <typename T>
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inline void SK_ANNOTATE_UNPROTECTED_WRITE(T* ptr, const T& val) {
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AnnotateIgnoreWritesBegin(__FILE__, __LINE__);
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*ptr = val;
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AnnotateIgnoreWritesEnd(__FILE__, __LINE__);
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}
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// Ignore racy reads and racy writes to this pointer, indefinitely.
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// If at all possible, use the more precise SK_ANNOTATE_UNPROTECTED_READ.
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template <typename T>
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void SK_ANNOTATE_BENIGN_RACE(T* ptr) {
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AnnotateBenignRaceSized(__FILE__, __LINE__, ptr, sizeof(*ptr), "SK_ANNOTATE_BENIGN_RACE");
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}
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#else // !DYNAMIC_ANNOTATIONS_ENABLED
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#define SK_ANNOTATE_UNPROTECTED_READ(x) (x)
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#define SK_ANNOTATE_UNPROTECTED_WRITE(ptr, val) *(ptr) = (val)
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#define SK_ANNOTATE_BENIGN_RACE(ptr)
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#endif
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// Can be used to wrap values that are intentionally racy, usually small mutable cached values, e.g.
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// - SkMatrix type mask
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// - SkPixelRef genIDs
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template <typename T>
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class SkTRacy {
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public:
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operator const T() const {
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return SK_ANNOTATE_UNPROTECTED_READ(fVal);
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}
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SkTRacy& operator=(const T& val) {
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SK_ANNOTATE_UNPROTECTED_WRITE(&fVal, val);
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return *this;
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}
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private:
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T fVal;
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};
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#endif//SkDynamicAnnotations_DEFINED
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