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* tweak SkOnce.h header to work around issues with ↵Gravatar Lee Salzman2016-12-16
| | | | | | | | | | | std::atomic::compare_exchange_strong BUG=skia: Change-Id: Id29c47cb4bec6a6d70d6514d18fa4ab9bd31b1e2 Reviewed-on: https://skia-review.googlesource.com/6200 Reviewed-by: Mike Klein <mtklein@chromium.org> Commit-Queue: Mike Klein <mtklein@chromium.org>
* Simplify implementation of SkOnce to not need so many comments.Gravatar mtklein2016-05-04
| | | | | | | | | | | | I think this version reads more clearly, and the key invariants are expressed in code rather than comments: - race losers always go through an acquire - we never exit the function unless fState is Done BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1951013004 Review-Url: https://codereview.chromium.org/1951013004
* Add reminders that these classes have constexpr default constructors.Gravatar mtklein2016-04-29
| | | | | | | | We can do this now that we can write "constexpr". GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1936653002 Review-Url: https://codereview.chromium.org/1936653002
* SkOnce: 2 bytes -> 1 byteGravatar mtklein2016-04-20
| | | | | | | | | | | | | | | | | | | | | | | | This uses the same logic we worked out for SkOncePtr to reduce the memory footprint of SkOnce from a done byte and lock byte to a single 3-state byte: - NotStarted: no thread has tried to run fn() yet - Active: a thread is running fn() - Done: fn() is complete Threads which see Done return immediately. Threads which see NotStarted try to move to Active, run fn(), then move to Done. Threads which see Active spin until the active thread moves to Done. This additionally fixes a too-weak memory order bug in SkOncePtr, and adds a big note to explain. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1904483003 Committed: https://skia.googlesource.com/skia/+/df02d338be8e3c1c50b48a3a9faa582703a39c07 Review URL: https://codereview.chromium.org/1904483003
* Revert of SkOnce: 2 bytes -> 1 byte (patchset #4 id:60001 of ↵Gravatar mtklein2016-04-20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | https://codereview.chromium.org/1904483003/ ) Reason for revert: bust the roll Original issue's description: > SkOnce: 2 bytes -> 1 byte > > This uses the same logic we worked out for SkOncePtr to reduce > the memory footprint of SkOnce from a done byte and lock byte > to a single 3-state byte: > > - NotStarted: no thread has tried to run fn() yet > - Active: a thread is running fn() > - Done: fn() is complete > > Threads which see Done return immediately. > Threads which see NotStarted try to move to Active, run fn(), then move to Done. > Threads which see Active spin until the active thread moves to Done. > > This additionally fixes a too-weak memory order bug in SkOncePtr, > and adds a big note to explain. > > BUG=skia: > GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1904483003 > > Committed: https://skia.googlesource.com/skia/+/df02d338be8e3c1c50b48a3a9faa582703a39c07 TBR=herb@google.com # Skipping CQ checks because original CL landed less than 1 days ago. NOPRESUBMIT=true NOTREECHECKS=true NOTRY=true BUG=skia: Review URL: https://codereview.chromium.org/1898413004
* SkOnce: 2 bytes -> 1 byteGravatar mtklein2016-04-20
| | | | | | | | | | | | | | | | | | | | | | This uses the same logic we worked out for SkOncePtr to reduce the memory footprint of SkOnce from a done byte and lock byte to a single 3-state byte: - NotStarted: no thread has tried to run fn() yet - Active: a thread is running fn() - Done: fn() is complete Threads which see Done return immediately. Threads which see NotStarted try to move to Active, run fn(), then move to Done. Threads which see Active spin until the active thread moves to Done. This additionally fixes a too-weak memory order bug in SkOncePtr, and adds a big note to explain. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1904483003 Review URL: https://codereview.chromium.org/1904483003
* Modernize and trim down SkOnce.Gravatar mtklein2016-04-18
| | | | | | | | | | | | | | | | | | | | | | | | | | The API and implementation are very much simplified. You may not want to bother reading the diff. As is our trend, SkOnce now uses <atomic> directly. Member initialization means we don't need SK_DECLARE_STATIC_ONCE. SkSpinlock already works this same way. All uses of the old API taking an external bool* and Lock* were pessimal, so I have not carried this sort of API forward. It's simpler, faster, and more space-efficient to always use this single SkOnce class interface. SkOnce weighs 2 bytes: a done bool and an SkSpinlock, also a bool internally. This API refactoring opens up the opportunity to fuse those into a single three-state byte if we'd like. No public API changes. TBR=reed@google.com BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1894893002 Review URL: https://codereview.chromium.org/1894893002
* Convert SkRefCnt to std::atomic.Gravatar bungeman2016-04-08
| | | | | | | | | | | This enables removing the more complicated atomic shims from SkAtomics.h. TBR=reed This doesn't actually change any API. CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-TSAN-Trybot,Test-Ubuntu-GCC-Golo-GPU-GT610-x86_64-Release-TSAN-Trybot Review URL: https://codereview.chromium.org/1867863002
* Modernize SkSpinlock.Gravatar mtklein2016-02-29
| | | | | | | | | | | | | | | | | | | | | | | | - Use std::atomic directly. - No more need for SkPODSpinlock or SK_DECLARE_STATIC_SPINLOCK. Now simple code like this works as you'd hope: static SkSpinlock gLock; That is, it starts unlocked and there's no static initializer. std::atomic_flag would make this terser and standard-guaranteed, but ATOMIC_FLAG_INIT caused not-yet-implemented errors on MSVC 2013. The generated code for this approach is identical. It appears the implicit constructor is constexpr when all the member initializers are. I'm hoping this way of producing constexpr constructors without typing "constexpr" gives us a way to eliminate more SkFoo / SkBaseFoo distinctions and SK_DECLARE_STATIC_FOO. This was certainly the easiest. BUG=skia: GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1734383002 Review URL: https://codereview.chromium.org/1734383002
* Move Mutexy things to private.Gravatar herb2015-09-29
There is no API change. TBR=reed@google.com BUG=skia: Review URL: https://codereview.chromium.org/1368333004
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