mirror of
https://github.com/klzgrad/naiveproxy.git
synced 2024-12-01 09:46:09 +03:00
51 lines
1.5 KiB
C++
51 lines
1.5 KiB
C++
// Copyright (c) 2013 The Chromium Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style license that can be
|
|
// found in the LICENSE file.
|
|
|
|
#ifndef BASE_ALLOCATOR_PARTITION_ALLOCATOR_SPIN_LOCK_H
|
|
#define BASE_ALLOCATOR_PARTITION_ALLOCATOR_SPIN_LOCK_H
|
|
|
|
#include <atomic>
|
|
#include <memory>
|
|
#include <mutex>
|
|
|
|
#include "base/base_export.h"
|
|
#include "base/compiler_specific.h"
|
|
|
|
// Spinlock is a simple spinlock class based on the standard CPU primitive of
|
|
// atomic increment and decrement of an int at a given memory address. These are
|
|
// intended only for very short duration locks and assume a system with multiple
|
|
// cores. For any potentially longer wait you should use a real lock, such as
|
|
// |base::Lock|.
|
|
namespace base {
|
|
namespace subtle {
|
|
|
|
class BASE_EXPORT SpinLock {
|
|
public:
|
|
SpinLock();
|
|
~SpinLock();
|
|
using Guard = std::lock_guard<SpinLock>;
|
|
|
|
ALWAYS_INLINE void lock() {
|
|
static_assert(sizeof(lock_) == sizeof(int),
|
|
"int and lock_ are different sizes");
|
|
if (LIKELY(!lock_.exchange(true, std::memory_order_acquire)))
|
|
return;
|
|
LockSlow();
|
|
}
|
|
|
|
ALWAYS_INLINE void unlock() { lock_.store(false, std::memory_order_release); }
|
|
|
|
private:
|
|
// This is called if the initial attempt to acquire the lock fails. It's
|
|
// slower, but has a much better scheduling and power consumption behavior.
|
|
void LockSlow();
|
|
|
|
std::atomic_int lock_{0};
|
|
};
|
|
|
|
} // namespace subtle
|
|
} // namespace base
|
|
|
|
#endif // BASE_ALLOCATOR_PARTITION_ALLOCATOR_SPIN_LOCK_H
|