mirror of
https://github.com/godotengine/godot.git
synced 2024-12-21 10:25:24 +08:00
111 lines
3.8 KiB
C++
111 lines
3.8 KiB
C++
/**************************************************************************/
|
|
/* spin_lock.h */
|
|
/**************************************************************************/
|
|
/* This file is part of: */
|
|
/* GODOT ENGINE */
|
|
/* https://godotengine.org */
|
|
/**************************************************************************/
|
|
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
|
|
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
|
|
/* */
|
|
/* Permission is hereby granted, free of charge, to any person obtaining */
|
|
/* a copy of this software and associated documentation files (the */
|
|
/* "Software"), to deal in the Software without restriction, including */
|
|
/* without limitation the rights to use, copy, modify, merge, publish, */
|
|
/* distribute, sublicense, and/or sell copies of the Software, and to */
|
|
/* permit persons to whom the Software is furnished to do so, subject to */
|
|
/* the following conditions: */
|
|
/* */
|
|
/* The above copyright notice and this permission notice shall be */
|
|
/* included in all copies or substantial portions of the Software. */
|
|
/* */
|
|
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
|
|
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
|
|
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
|
|
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
|
|
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
|
|
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
|
|
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
|
|
/**************************************************************************/
|
|
|
|
#ifndef SPIN_LOCK_H
|
|
#define SPIN_LOCK_H
|
|
|
|
#include "core/typedefs.h"
|
|
|
|
#ifdef _MSC_VER
|
|
#include <intrin.h>
|
|
#endif
|
|
|
|
#if defined(__APPLE__)
|
|
|
|
#include <os/lock.h>
|
|
|
|
class SpinLock {
|
|
mutable os_unfair_lock _lock = OS_UNFAIR_LOCK_INIT;
|
|
|
|
public:
|
|
_ALWAYS_INLINE_ void lock() const {
|
|
os_unfair_lock_lock(&_lock);
|
|
}
|
|
|
|
_ALWAYS_INLINE_ void unlock() const {
|
|
os_unfair_lock_unlock(&_lock);
|
|
}
|
|
};
|
|
|
|
#else
|
|
|
|
#include "core/os/thread.h"
|
|
|
|
#include <atomic>
|
|
|
|
_ALWAYS_INLINE_ static void _cpu_pause() {
|
|
#if defined(_MSC_VER)
|
|
// ----- MSVC.
|
|
#if defined(_M_ARM) || defined(_M_ARM64) // ARM.
|
|
__yield();
|
|
#elif defined(_M_IX86) || defined(_M_X64) // x86.
|
|
_mm_pause();
|
|
#endif
|
|
#elif defined(__GNUC__) || defined(__clang__)
|
|
// ----- GCC/Clang.
|
|
#if defined(__i386__) || defined(__x86_64__) // x86.
|
|
__builtin_ia32_pause();
|
|
#elif defined(__arm__) || defined(__aarch64__) // ARM.
|
|
asm volatile("yield");
|
|
#elif defined(__powerpc__) || defined(__ppc__) || defined(__PPC__) // PowerPC.
|
|
asm volatile("or 27,27,27");
|
|
#elif defined(__riscv) // RISC-V.
|
|
asm volatile(".insn i 0x0F, 0, x0, x0, 0x010");
|
|
#endif
|
|
#endif
|
|
}
|
|
|
|
static_assert(std::atomic_bool::is_always_lock_free);
|
|
|
|
class alignas(Thread::CACHE_LINE_BYTES) SpinLock {
|
|
mutable std::atomic<bool> locked = ATOMIC_VAR_INIT(false);
|
|
|
|
public:
|
|
_ALWAYS_INLINE_ void lock() const {
|
|
while (true) {
|
|
bool expected = false;
|
|
if (locked.compare_exchange_weak(expected, true, std::memory_order_acquire, std::memory_order_relaxed)) {
|
|
break;
|
|
}
|
|
do {
|
|
_cpu_pause();
|
|
} while (locked.load(std::memory_order_relaxed));
|
|
}
|
|
}
|
|
|
|
_ALWAYS_INLINE_ void unlock() const {
|
|
locked.store(false, std::memory_order_release);
|
|
}
|
|
};
|
|
|
|
#endif // __APPLE__
|
|
|
|
#endif // SPIN_LOCK_H
|