diff options
author | mtklein <mtklein@chromium.org> | 2016-05-05 16:05:56 -0700 |
---|---|---|
committer | Commit bot <commit-bot@chromium.org> | 2016-05-05 16:05:56 -0700 |
commit | ffa4a9213b4e754adc210fa02a3c4b1ae8d3b6d0 (patch) | |
tree | e6f20243b4ed7c36e36302d914e255dfa6799217 /include | |
parent | 4017007b288087c07c596baa9fe8ecf485bca1c3 (diff) |
SkOncePtr -> SkOnce
It's always nice to kill off a synchronization primitive.
And while less terse, I think this new code reads more clearly.
... and, SkOncePtr's tests were the only thing now using sk_num_cores()
outside of SkTaskGroup, so I've hidden it as static inside SkTaskGroup.cpp.
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1953533002
CQ_EXTRA_TRYBOTS=client.skia:Test-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release-SKNX_NO_SIMD-Trybot
Committed: https://skia.googlesource.com/skia/+/9bd3fc7fa9bb7cad050bd619aa93d4c48ebb5c02
Review-Url: https://codereview.chromium.org/1953533002
Diffstat (limited to 'include')
-rw-r--r-- | include/private/SkOncePtr.h | 65 |
1 files changed, 0 insertions, 65 deletions
diff --git a/include/private/SkOncePtr.h b/include/private/SkOncePtr.h deleted file mode 100644 index 921c6a6534..0000000000 --- a/include/private/SkOncePtr.h +++ /dev/null @@ -1,65 +0,0 @@ -/* - * Copyright 2015 Google Inc. - * - * Use of this source code is governed by a BSD-style license that can be - * found in the LICENSE file. - */ - -#ifndef SkOncePtr_DEFINED -#define SkOncePtr_DEFINED - -#include "../private/SkAtomics.h" -#include <memory> - -// Use this to create a global static pointer that's intialized exactly once when you call get(). -#define SK_DECLARE_STATIC_ONCE_PTR(type, name) namespace {} static SkBaseOncePtr<type> name; - -template <typename T> -class SkBaseOncePtr { -public: - template <typename F> - T* get(const F& f) const { - uintptr_t state = sk_atomic_load(&fState, sk_memory_order_acquire); - if (state < 2) { - if (state == 0) { - // It looks like no one has tried to create our pointer yet. - // We try to claim that task by atomically swapping our state from '0' to '1'. - // See SkOnce.h for why we use an acquire memory order here rather than relaxed. - if (sk_atomic_compare_exchange( - &fState, &state, (uintptr_t)1, sk_memory_order_acquire, sk_memory_order_acquire)) { - // We've claimed it. Create our pointer and store it into fState. - state = (uintptr_t)f(); - SkASSERT(state > 1); - sk_atomic_store(&fState, state, sk_memory_order_release); - } else { - // Someone else claimed it. - // We fall through to the spin loop just below to wait for them to finish. - } - } - - while (state == 1) { - // State '1' is our busy-but-not-done state. - // Some other thread has claimed the job of creating our pointer. - // We just need to wait for it to finish. - state = sk_atomic_load(&fState, sk_memory_order_acquire); - } - - // We shouldn't be able to get here without having created our pointer. - SkASSERT(state > 1); - } - return (T*)state; - } - - operator T*() const { - auto state = sk_atomic_load(&fState, sk_memory_order_acquire); - return state < 2 ? nullptr : (T*)state; - // TODO: If state == 1 spin until it's not? - } - - // fState == 0 --> we have not created our ptr yet - // fState == 1 --> someone is in the middle of creating our ptr - // else --> (T*)fState is our ptr - mutable uintptr_t fState; -}; - -#endif//SkOncePtr_DEFINED |