skia2/include/private/SkSpinlock.h
Mike Klein c0bd9f9fe5 rewrite includes to not need so much -Ifoo
Current strategy: everything from the top

Things to look at first are the manual changes:

   - added tools/rewrite_includes.py
   - removed -Idirectives from BUILD.gn
   - various compile.sh simplifications
   - tweak tools/embed_resources.py
   - update gn/find_headers.py to write paths from the top
   - update gn/gn_to_bp.py SkUserConfig.h layout
     so that #include "include/config/SkUserConfig.h" always
     gets the header we want.

No-Presubmit: true
Change-Id: I73a4b181654e0e38d229bc456c0d0854bae3363e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/209706
Commit-Queue: Mike Klein <mtklein@google.com>
Reviewed-by: Hal Canary <halcanary@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
2019-04-24 16:27:11 +00:00

48 lines
1.3 KiB
C++

/*
* 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 SkSpinlock_DEFINED
#define SkSpinlock_DEFINED
#include "include/core/SkTypes.h"
#include <atomic>
class SkSpinlock {
public:
constexpr SkSpinlock() = default;
void acquire() {
// To act as a mutex, we need an acquire barrier when we acquire the lock.
if (fLocked.exchange(true, std::memory_order_acquire)) {
// Lock was contended. Fall back to an out-of-line spin loop.
this->contendedAcquire();
}
}
// Acquire the lock or fail (quickly). Lets the caller decide to do something other than wait.
bool tryAcquire() {
// To act as a mutex, we need an acquire barrier when we acquire the lock.
if (fLocked.exchange(true, std::memory_order_acquire)) {
// Lock was contended. Let the caller decide what to do.
return false;
}
return true;
}
void release() {
// To act as a mutex, we need a release barrier when we release the lock.
fLocked.store(false, std::memory_order_release);
}
private:
SK_API void contendedAcquire();
std::atomic<bool> fLocked{false};
};
#endif//SkSpinlock_DEFINED