struct mylock {
    pthread_mutex_t entry;
    pthread_mutex_t manager;
    pthread_mutex_t core;
    int counter;
    int state;
}

void mylock_acquire(struct mylock *lock, int state)
{
    assert(state != 0);
    pthread_mutex_lock(&lock->entry);
    pthread_mutex_lock(&lock->manager);
    if (lock->state != state) {
        pthread_mutex_unlock(&lock->manager);
        pthread_mutex_lock(&lock->core);
        pthread_mutex_lock(&lock->manager);
        lock->state = state;
    }
    ++lock->counter;
    pthread_mutex_unlock(&lock->manager);
    pthread_mutex_unlock(&lock->entry);
}

void mylock_release(struct mylock *lock)
{
    pthread_mutex_lock(&lock->manager);
    if (--lock->counter == 0) {
        lock->state = 0;
        pthread_mutex_unlock(&lock->core);
    }
    pthread_mutex_unlock(&lock->manager);
}