From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- gfx/angle/checkout/src/common/Spinlock.h | 71 ++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) create mode 100644 gfx/angle/checkout/src/common/Spinlock.h (limited to 'gfx/angle/checkout/src/common/Spinlock.h') diff --git a/gfx/angle/checkout/src/common/Spinlock.h b/gfx/angle/checkout/src/common/Spinlock.h new file mode 100644 index 0000000000..494da0943e --- /dev/null +++ b/gfx/angle/checkout/src/common/Spinlock.h @@ -0,0 +1,71 @@ +// +// Copyright 2021 The ANGLE Project Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. +// +// Spinlock.h: +// Spinlock is a lock that loops actively until it gets the resource. +// Only use it when the lock will be granted in reasonably short time. + +#ifndef COMMON_SPINLOCK_H_ +#define COMMON_SPINLOCK_H_ + +#include + +// TODO(jplate) Add pause for ARM, http://anglebug.com:6067 +#if defined(_MSC_VER) && (defined(_M_IX86) || defined(_M_X64)) +extern "C" void _mm_pause(); +# pragma intrinsic(_mm_pause) +# define ANGLE_SMT_PAUSE() _mm_pause() +#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__)) +# define ANGLE_SMT_PAUSE() __asm__ __volatile__("pause;") +#else +# define ANGLE_SMT_PAUSE() static_cast(0) +#endif + +namespace angle +{ + +class Spinlock +{ + public: + Spinlock() noexcept; + + bool try_lock() noexcept; + void lock() noexcept; + void unlock() noexcept; + + private: + std::atomic_bool mLock; +}; + +inline Spinlock::Spinlock() noexcept : mLock(false) {} + +inline bool Spinlock::try_lock() noexcept +{ + // Relaxed check first to prevent unnecessary cache misses. + return !mLock.load(std::memory_order_relaxed) && + !mLock.exchange(true, std::memory_order_acquire); +} + +inline void Spinlock::lock() noexcept +{ + while (mLock.exchange(true, std::memory_order_acquire)) + { + // Relaxed wait to prevent unnecessary cache misses. + while (mLock.load(std::memory_order_relaxed)) + { + // Optimization for simultaneous multithreading. + ANGLE_SMT_PAUSE(); + } + } +} + +inline void Spinlock::unlock() noexcept +{ + mLock.store(false, std::memory_order_release); +} + +} // namespace angle + +#endif // COMMON_SPINLOCK_H_ -- cgit v1.2.3