多线程锁的一点测试

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C++11提供了原子操作atomic；而在一些代码中，也会经常看到利用原子操作来实现spinklock（pthread提供的spinklock似乎性能不如mutex）。
于是，我就来试试用atomic来实现spinklock。
测试，仅仅是测试lock/unlock。测试平台是windows和linux.
测试结果，两种锁耗时完全一样；（另外，windows耗时大约是linux耗时的2倍）

测试结论：感觉，没有必要用spinklock，因为性能几乎没有差别；而spinklock用着还需要非常小心，因为它是忙等待（死循环等待）.

#include <ctime>#include <mutex>#include <atomic>class SpinLock{public:    SpinLock(){}    ~SpinLock(){}    void Lock()    {        //如果已经有人set了，那么返回true;如果没有set，那么set并且返回false;        while (flag_.test_and_set())        {            //do nothing;        }    }    void UnLock()    {        flag_.clear();    }private:    std::atomic_flag flag_;};struct SpinkLockGuard{public:    SpinkLockGuard(SpinLock &l) :spinlock_(l)    {        spinlock_.Lock();    }    ~SpinkLockGuard()    {        spinlock_.UnLock();    }private:    SpinLock &spinlock_;};int32_t times = 10*1024 * 1024;//#define COST(t1,t0) ((t1.tv_sec-t0.tv_sec)*1000*1000 + (t1.tv_usec-t0.tv_usec))#define COST(tv1,tv0) (int64_t)(((tv1-tv0)*1000*1000)/CLOCKS_PER_SEC)void time_show(int64_t cost){    int64_t old = cost;    int32_t avg = (int32_t)(cost / times);    int32_t r_usec = cost % (1000);    cost = (int64_t)(cost / (1000));    int32_t r_msec = cost % 1000;    cost = (int64_t)(cost / (1000));    printf("[test]lock/unlock %d times\n", times);    printf("[test]\t cost all time (%ld:%d:%d)[s:ms:us](%ld'us) \n", cost, r_msec, r_usec, old);    printf("[test]\t cost avt = (%d:%d)[ms:us](one msg)\n", (int32_t)(avg / 1000), (int32_t)(avg % 1000));}void test_lock(){    clock_t tv0, tv1;    tv0 = clock();    SpinLock lock_;    for (int32_t i = 0; i != times; ++i)    {        SpinkLockGuard guard(lock_);    }    tv1 = clock();    printf("spinklock cost time:\n");    time_show(COST(tv1, tv0));    clock_t tv2, tv3;    tv2 = clock();    std::mutex mutex_;    for (int32_t i = 0; i != times; ++i)    {        std::lock_guard<std::mutex> guard(mutex_);    }    tv3 = clock();    printf("\n---------------------------\nmutex lock cost time:\n");    time_show(COST(tv1, tv0));}int main(){    test_lock();    return 0;}

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