sem_init函数的返回值是什么

应该这样

#define CHECK(_sem) (sem_init(&(_sem)->sem, (pshared), (value)) == 0) ? ((_sem)->valid = true, 0) : ((_sem)->valid = false, -1)

然后使用的地方为

ret = CHECK(_sem)

也就是说，sem_init返回0时，_sem->valid被设置成true, ret被设置为0,

sem_init返回非0时，_sem->valid被设置成false, ret被设置为-1

struct rwlock

{

    sem_t read

    sem_t write

    int reads

}

void RWLock_Init(rwlock &lock)

{

    sem_init(lock.read, 0, 1)

    sem_init(lock.write, 0, 1)

    lock.reads = 0

}

void Acquir_read_lock(rwlock &lock)

{

    sem_wait(&lock.read)

    ++lock.reads

    if(lock.reads == 1)

    {

        sem_wait(&lock.write)

    }

    sem_post(&lock.write)

}

void acquir_read_unlock(rwlock &lock)

{

    sem_wait(&lock.read)

    --lock.reads

    if(lock.reads == 0)

    {

        sem_post(&lock.write)

    }

    sem_post(&lcok.read)

}

void acquir_write_lock(rwlock &lock)

{

    sem_wait(&lock.write)

}

void acquir_write_unlock(rwlock * lock)

{

    sem_post(&lock.write)

}

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