104 lines
2.1 KiB
C++
104 lines
2.1 KiB
C++
// Copyright 2009-2021 Intel Corporation
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// SPDX-License-Identifier: Apache-2.0
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#pragma once
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#include "platform.h"
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#include "intrinsics.h"
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#include "atomic.h"
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#define CPU_CACHELINE_SIZE 64
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namespace embree
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{
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/*! system mutex */
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class MutexSys {
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friend struct ConditionImplementation;
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public:
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MutexSys();
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~MutexSys();
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private:
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MutexSys (const MutexSys& other) DELETED; // do not implement
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MutexSys& operator= (const MutexSys& other) DELETED; // do not implement
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public:
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void lock();
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bool try_lock();
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void unlock();
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protected:
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void* mutex;
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};
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/*! spinning mutex */
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class SpinLock
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{
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public:
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SpinLock ()
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: flag(false) {}
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__forceinline bool isLocked() {
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return flag.load();
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}
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__forceinline void lock()
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{
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while (true)
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{
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while (flag.load())
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{
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_mm_pause();
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_mm_pause();
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}
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bool expected = false;
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if (flag.compare_exchange_strong(expected,true,std::memory_order_acquire))
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break;
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}
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}
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__forceinline bool try_lock()
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{
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bool expected = false;
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if (flag.load() != expected) {
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return false;
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}
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return flag.compare_exchange_strong(expected,true,std::memory_order_acquire);
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}
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__forceinline void unlock() {
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flag.store(false,std::memory_order_release);
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}
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__forceinline void wait_until_unlocked()
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{
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while(flag.load())
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{
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_mm_pause();
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_mm_pause();
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}
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}
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public:
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atomic<bool> flag;
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};
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class PaddedSpinLock : public SpinLock
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{
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private:
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MAYBE_UNUSED char padding[CPU_CACHELINE_SIZE - sizeof(SpinLock)];
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};
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/*! safe mutex lock and unlock helper */
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template<typename Mutex> class Lock {
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public:
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Lock (Mutex& mutex) : mutex(mutex), locked(true) { mutex.lock(); }
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Lock (Mutex& mutex, bool locked) : mutex(mutex), locked(locked) {}
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~Lock() { if (locked) mutex.unlock(); }
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__forceinline void lock() { assert(!locked); locked = true; mutex.lock(); }
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__forceinline bool isLocked() const { return locked; }
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protected:
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Mutex& mutex;
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bool locked;
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};
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}
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