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C 置R/W内存屏障 static inline void MemoryBarrier() noexcept{std::atomic_thread_fence(std::memory_order_seq_cst);}
头文件
#pragma once#include ppp/stdafx.hnamespace ppp
{namespace threading{class SpinLock final{public:explicit SpinLock() noexcept;SpinLock(const SpinLock) delete;SpinLock(SpinLock) delete;~SpinLock() noexcept(false);public:SpinLock operator(const SpinLock) delete;public:bool TryEnter() noexcept;bool TryEnter(int loop, int timeout) noexcept;void Enter() noexcept;void Leave();inline bool IsLockTaken() noexcept { return _.load(); }public:inline void lock() noexcept { Enter(); }inline void unlock() noexcept { Leave(); }public:std::atomicbool _;};class RecursiveSpinLock final{public:explicit RecursiveSpinLock() noexcept;RecursiveSpinLock(const RecursiveSpinLock) delete;RecursiveSpinLock(RecursiveSpinLock) delete;~RecursiveSpinLock() default;public:RecursiveSpinLock operator(const RecursiveSpinLock) delete;public:bool TryEnter() noexcept;bool TryEnter(int loop, int timeout) noexcept;void Enter() noexcept;void Leave();inline bool IsLockTaken() noexcept { return lockobj_.IsLockTaken(); }public:inline void lock() noexcept { Enter(); }inline void unlock() noexcept { Leave(); }public:SpinLock lockobj_;volatile int tid_;std::atomicint reentries_;};}
}
源文件
#include ppp/threading/SpinLock.h
#include ppp/threading/Thread.hnamespace ppp
{namespace threading{template class LockObjectstatic constexpr bool Lock_TryEnter(LockObject lock, int loop,int timeout) noexcept{bool lockTaken false;if (loop -1){uint64_t last GetTickCount();for (int i 0; i loop; i){lockTaken lock.TryEnter();if (lockTaken){break;}if (timeout -1){uint64_t now GetTickCount();int64_t diff now - last;if (diff timeout){break;}}}}else{uint64_t last GetTickCount();for (;;){lockTaken lock.TryEnter();if (lockTaken){break;}if (timeout -1){uint64_t now GetTickCount();int64_t diff now - last;if (diff timeout){break;}}}}return lockTaken;}template class LockObject, class LockInternalObject, typename... TryEnterArgumentsstatic constexpr bool RecursiveLock_TryEnter(LockObject lock, LockInternalObject lock_internal, volatile int* tid,std::atomicint reentries, TryEnterArguments... arguments){int n reentries;assert(n 0);int current_tid std::hashstd::thread::id{}(std::this_thread::get_id());if (n 1){bool lockTaken lock_internal.TryEnter(std::forwardTryEnterArguments(arguments)...);if (!lockTaken){reentries--;return false;}Thread::MemoryBarrier();*tid current_tid;Thread::MemoryBarrier();}else{Thread::MemoryBarrier();int lockTaken_tid *tid;Thread::MemoryBarrier();if (lockTaken_tid current_tid){lock.Leave();return false;}}return true;}SpinLock::SpinLock() noexcept: _(false){}SpinLock::~SpinLock() noexcept(false){bool lockTaken IsLockTaken();if (lockTaken){throw std::runtime_error(fail to release the atomic lock.);}}void SpinLock::Enter() noexcept{for (;;) {bool lockTaken TryEnter();if (lockTaken){break;}}}bool SpinLock::TryEnter(int loop, int timeout) noexcept{return Lock_TryEnter(*this, loop, timeout);}bool SpinLock::TryEnter() noexcept{bool expected false;return _.compare_exchange_strong(expected, true, std::memory_order_acquire);}void SpinLock::Leave(){bool expected true;if (!_.compare_exchange_strong(expected, false, std::memory_order_release)){throw std::runtime_error(failed to acquire the atomic lock.);}}RecursiveSpinLock::RecursiveSpinLock() noexcept: lockobj_(), tid_(0), reentries_(0){}bool RecursiveSpinLock::TryEnter() noexcept{return RecursiveLock_TryEnter(*this, lockobj_, tid_, reentries_);}bool RecursiveSpinLock::TryEnter(int loop, int timeout) noexcept{return RecursiveLock_TryEnter(*this, lockobj_, tid_, reentries_, loop, timeout);}void RecursiveSpinLock::Enter() noexcept{for (;;){bool lockTaken TryEnter();if (lockTaken){break;}}}void RecursiveSpinLock::Leave() {int n --reentries_;assert(n 0);if (n 0){lockobj_.Leave();}}}
}
