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Code Releases Wiki Activity

Enhance SpinLock

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This commit is contained in:
Pedro J. Estébanez
2024-11-04 18:35:23 +01:00
parent 95c6a24795
commit 360ed2b00d
1 changed files with 42 additions and 5 deletions
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47
core/os/spin_lock.h
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@@ -33,6 +33,10 @@
#include "core/typedefs.h"
#ifdef _MSC_VER
#include <intrin.h>
#endif
#if defined(__APPLE__)
#include <os/lock.h>
@@ -52,19 +56,52 @@ public:
#else
#include "core/os/thread.h"
#include <atomic>
class SpinLock {
mutable std::atomic_flag locked = ATOMIC_FLAG_INIT;
_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 (locked.test_and_set(std::memory_order_acquire)) {
// Continue.
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.clear(std::memory_order_release);
locked.store(false, std::memory_order_release);
}
};