Question

我在Mac上找不到它，但几乎所有Linux操作系统都支持它。任何人都知道如何将它移植到mac？

Answer 1

这是替换代码。您应该能够将其放在头文件中并将其放入项目中。

typedef int pthread_spinlock_t;

int pthread_spin_init(pthread_spinlock_t *lock, int pshared) {
    __asm__ __volatile__ ("" ::: "memory");
    *lock = 0;
    return 0;
}

int pthread_spin_destroy(pthread_spinlock_t *lock) {
    return 0;
}

int pthread_spin_lock(pthread_spinlock_t *lock) {
    while (1) {
        int i;
        for (i=0; i < 10000; i++) {
            if (__sync_bool_compare_and_swap(lock, 0, 1)) {
                return 0;
            }
        }
        sched_yield();
    }
}

int pthread_spin_trylock(pthread_spinlock_t *lock) {
    if (__sync_bool_compare_and_swap(lock, 0, 1)) {
        return 0;
    }
    return EBUSY;
}

int pthread_spin_unlock(pthread_spinlock_t *lock) {
    __asm__ __volatile__ ("" ::: "memory");
    *lock = 0;
    return 0;
}

请参阅discussion和Github source

编辑：这是一个适用于所有操作系统的类，其中包含OSX上缺少pthread螺旋锁的解决方法：

class Spinlock
{
private:    //private copy-ctor and assignment operator ensure the lock never gets copied, which might cause issues.
    Spinlock operator=(const Spinlock & asdf);
    Spinlock(const Spinlock & asdf);
#ifdef __APPLE__
    OSSpinLock m_lock;
public:
    Spinlock()
    : m_lock(0)
    {}
    void lock() {
        OSSpinLockLock(&m_lock);
    }
    bool try_lock() {
        return OSSpinLockTry(&m_lock);
    }
    void unlock() {
        OSSpinLockUnlock(&m_lock);
    }
#else
    pthread_spinlock_t m_lock;
public:
    Spinlock() {
        pthread_spin_init(&m_lock, 0);
    }

    void lock() {
        pthread_spin_lock(&m_lock);
    }
    bool try_lock() {
        int ret = pthread_spin_trylock(&m_lock);
        return ret != 16;   //EBUSY == 16, lock is already taken
    }
    void unlock() {
        pthread_spin_unlock(&m_lock);
    }
    ~Spinlock() {
        pthread_spin_destroy(&m_lock);
    }
#endif
};

Answer 2

尝试使用OSSpinLock。文档在这里：http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/spinlock.3.html

Answer 3

如果锁的性能不重要，pthread_mutex_t可以用作pthread_spinlock_t的drop替换，这使得移植变得容易。

Answer 4

我改用了（OS X intel 原生支持）

pthread_rwlock_t 锁；
pthread_rwlock_init
pthread_rwlock_wrlock
pthread_rwlock_unlock

而且效果也很好

Mac OS X是否有pthread_spinlock_t类型？

4 个答案: