用C++11实现spinlock

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我的 spin lock 代码：

#include <atomic>#include <unistd.h>struct SpinLock;struct SpinLock_t {private:  std::atomic<char> stat;  static const char UNLOCK_STAT = 0;  static const char LOCK_STAT = 1;public:  SpinLock_t() : stat(UNLOCK_STAT) {}private:  friend class SpinLock;  SpinLock_t(const SpinLock_t& s);   SpinLock_t operator=(const SpinLock_t& s); };struct SpinLock {private:  SpinLock_t *s_;public:  SpinLock(SpinLock_t* s):s_(s) {    char unlock_stat = SpinLock_t::UNLOCK_STAT;    while (!(s_->stat).compare_exchange_weak(unlock_stat,      SpinLock_t::LOCK_STAT, std::memory_order_acq_rel)) {      unlock_stat = SpinLock_t::UNLOCK_STAT;      sleep(0);    }     }  ~SpinLock() {    (s_->stat).store(SpinLock_t::UNLOCK_STAT, std::memory_order_release);  }private:  SpinLock(const SpinLock& s);   SpinLock& operator=(const SpinLock& s); };

测试框架：

#include <vector>#include <iostream>#include <thread>#include "SpinLock.h"#include <mutex>using namespace std;SpinLock_t s;std::mutex m;int g = 0;void f1() {  for (int i = 0; i < 10000000; ++i) {    m.lock();    ++g;    m.unlock();  }}void f2() {  for (int i = 0; i < 10000000; ++i) {    {         SpinLock spinlock(&s);      ++g;    }     }}int main(){  std::vector<std::thread> v;  for (int n = 0; n < 1; ++n) {    v.emplace_back(f1);    v.emplace_back(f2);  }  for (auto& t : v) {    t.join();  }  cout << g << endl;}

测试结果：

在并发严重的情况下，我实现的spinlock和mutex比，运行时间略长，总体性能略差。但是我实现的spinlock开销的系统时间比mutex少了不少，spinlock本来就不是用于竞争非常严重、临界区非常长的的场景：）

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