C++ pthread_rwlock_tryrdlock函数代码示例

void* run_free_cache(void* args) {
    AtomicCacheBase::m_last_expired_ms = currentms();
    uint64_t cur_ms = 0;
    while (AtomicCacheBase::m_run_thread) {
       int ret = pthread_rwlock_tryrdlock(AtomicCacheBase::m_rwlock);
        Sleeper sleeper;
        while (ret != 0) {
            sleeper.wait();
            ret = pthread_rwlock_tryrdlock(AtomicCacheBase::m_rwlock);
        }
       // printf("rd lock %d\n",ret);  
        AtomicQueue<AtomicCacheBase*>::iterator iter = AtomicCacheBase::m_caches->begin();
        int i = 0;
        for (; iter != AtomicCacheBase::m_caches->end(); iter++) {
            (*iter)->run_free();
            //printf("free caches %d node_t %p base %p\n", i++, iter.ptr, *iter);
        }
       pthread_rwlock_unlock(AtomicCacheBase::m_rwlock);
       // printf("un lock rd %d\n",ret);  
        // sleep
        // if process has timer it will break when the timer expires
        // so we need to make sure the real time
        cur_ms = currentms();
        while (cur_ms < AtomicCacheBase::m_last_expired_ms + AtomicCacheBase::m_max_delay_seconds * 1000) {
            usleep(1000 * (AtomicCacheBase::m_last_expired_ms + AtomicCacheBase::m_max_delay_seconds * 1000 - cur_ms));
            cur_ms = currentms();
        }
        AtomicCacheBase::m_last_expired_ms = cur_ms;
    }
    return NULL;
}

bool SafeMaze::TestRWLock()
{
	for(unsigned int i = 0; i < m_uiY; i++)
	{
		for(unsigned int j = 0; j < m_uiX; j++)
			pthread_rwlock_rdlock(&m_ppObjsMutex[i][j]);
	}

	for(unsigned int i = 0; i < m_uiY; i++)
	{
		for(unsigned int j = 0; j < m_uiX; j++)
		{
			bool ret = (pthread_rwlock_tryrdlock(&m_ppObjsMutex[i][j]) == 0 && pthread_rwlock_trywrlock(&m_ppObjsMutex[i][j]) != 0);
			if(ret)
			{
				pthread_rwlock_unlock(&m_ppObjsMutex[i][j]);
				pthread_rwlock_unlock(&m_ppObjsMutex[i][j]);
				continue;
			}
			else
			{
				std::cout << "rwlock, x: " << j << " y: " << i << " has exception." << std::endl;
				pthread_rwlock_unlock(&m_ppObjsMutex[i][j]);
				pthread_rwlock_unlock(&m_ppObjsMutex[i][j]);
				return false;
			}
		}
	}

	for(unsigned int i = 0; i < m_uiY; i++)
	{
		for(unsigned int j = 0; j < m_uiX; j++)
		{
			pthread_rwlock_wrlock(&m_ppObjsMutex[i][j]);
		}
	}

	for(unsigned int i = 0; i < m_uiY; i++)
	{
		for(unsigned int j = 0; j < m_uiX; j++)
		{
			bool ret = (pthread_rwlock_tryrdlock(&m_ppObjsMutex[i][j]) != 0 && pthread_rwlock_trywrlock(&m_ppObjsMutex[i][j]));
			if(ret)
			{
				pthread_rwlock_unlock(&m_ppObjsMutex[i][j]);
				continue;
			}
			else
			{
				std::cout << "rwlock, x: " << j << " y: " << i << " has exception." << std::endl;
				pthread_rwlock_unlock(&m_ppObjsMutex[i][j]);
				return false;
			}
		}
	}
	return true;
}

void *di_rwlock_rdlock_held(di_rwlock_t * self, pthread_rwlock_t *held_lock) {
    while (1) {
        if (pthread_rwlock_tryrdlock(&self->rwlock1) == 0) {
            *held_lock = self->rwlock1;
            return self->instance1;
        }
        if (pthread_rwlock_tryrdlock(&self->rwlock2) == 0) {
            *held_lock = self->rwlock2;
            return self->instance2;
        }
    }
}

TEST(pthread, pthread_rwlock_smoke) {
  pthread_rwlock_t l;
  ASSERT_EQ(0, pthread_rwlock_init(&l, NULL));

  // Single read lock
  ASSERT_EQ(0, pthread_rwlock_rdlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

  // Multiple read lock
  ASSERT_EQ(0, pthread_rwlock_rdlock(&l));
  ASSERT_EQ(0, pthread_rwlock_rdlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

  // Write lock
  ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

  // Try writer lock
  ASSERT_EQ(0, pthread_rwlock_trywrlock(&l));
  ASSERT_EQ(EBUSY, pthread_rwlock_trywrlock(&l));
  ASSERT_EQ(EBUSY, pthread_rwlock_tryrdlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

  // Try reader lock
  ASSERT_EQ(0, pthread_rwlock_tryrdlock(&l));
  ASSERT_EQ(0, pthread_rwlock_tryrdlock(&l));
  ASSERT_EQ(EBUSY, pthread_rwlock_trywrlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

  // Try writer lock after unlock
  ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

#ifdef __BIONIC__
  // EDEADLK in "read after write"
  ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
  ASSERT_EQ(EDEADLK, pthread_rwlock_rdlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));

  // EDEADLK in "write after write"
  ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
  ASSERT_EQ(EDEADLK, pthread_rwlock_wrlock(&l));
  ASSERT_EQ(0, pthread_rwlock_unlock(&l));
#endif

  ASSERT_EQ(0, pthread_rwlock_destroy(&l));
}

void *rdlockThread(void *arg)
{
  int             rc;
  int             count=0;

  printf("Entered thread, getting read lock with mp wait\n");
  Retry:
  rc = pthread_rwlock_tryrdlock(&rwlock);
  if (rc == EBUSY) {
    if (count >= 10) {
      printf("Retried too many times, failure!\n");

      exit(EXIT_FAILURE);
    }
    ++count;
    printf("Could not get lock, do other work, then RETRY...\n");
    sleep(1);
    goto Retry;
  }
  compResults("pthread_rwlock_tryrdlock() 1\n", rc);

  sleep(2);

  printf("unlock the read lock\n");
  rc = pthread_rwlock_unlock(&rwlock);
  compResults("pthread_rwlock_unlock()\n", rc);

  printf("Secondary thread complete\n");
  return NULL;
}

void *tf10(void *arg)
{
	pthread_rwlock_t q_rwlock;
	long long count;
	struct job *p,*q;
	struct job *task=NULL;
	pthread_t tid;
	struct timeval begintime,endtime;
	float elapsed_time;
	tid=pthread_self();
	count=0;
	while(count<100000000)
	{
		if(pthread_rwlock_tryrdlock(&q_rwlock)==0)
		{
			q=(struct job*)arg;
			p=q->next;
			while(p!=NULL)
			{
				if(tid==p->tid)
					count++;
				p=p->next;
			}
			pthread_rwlock_unlock(&q_rwlock);
		}
	}
	gettimeofday(&endtime,NULL);
	elapsed_time=1000000*(endtime.tv_sec-begintime.tv_sec)+endtime.tv_usec-begintime.tv_usec;
	endtime.tv_usec-begintime.tv_usec;
	elapsed_time/=1000000;
	printf("This total used time is :%f seconds.\n",elapsed_time);
	return (void *)0;
}

 bool RWLock::try_read_lock()
 {
     IMPL(impl);
     if (pthread_rwlock_tryrdlock(&impl->rwlock) == 0)
         return true;
     return false;
 }

int main(int argc, char** argv)
{
  int r;
  pthread_mutex_t mutex;
  pthread_rwlock_t rwlock;
  struct timespec abs_timeout;

  time(&abs_timeout.tv_sec);
  abs_timeout.tv_nsec = 0;
  abs_timeout.tv_sec += 10;

  r = pthread_rwlock_init(&rwlock, NULL); assert(r == 0);
  fprintf(stderr, "Locking rwlock via pthread_rwlock_wrlock().\n");
  r = pthread_rwlock_wrlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  fprintf(stderr, "Locking rwlock via pthread_rwlock_trywrlock().\n");
  r = pthread_rwlock_trywrlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  fprintf(stderr, "Locking rwlock via pthread_rwlock_timedwrlock().\n");
#ifdef HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK
  r = pthread_rwlock_timedwrlock(&rwlock, &abs_timeout); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
#endif
  fprintf(stderr, "Locking rwlock via pthread_rwlock_rdlock().\n");
  r = pthread_rwlock_rdlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_rdlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_rdlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  fprintf(stderr, "Locking rwlock via pthread_rwlock_tryrdlock().\n");
  r = pthread_rwlock_tryrdlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  fprintf(stderr, "Locking rwlock via pthread_rwlock_timedrdlock().\n");
#ifdef HAVE_PTHREAD_RWLOCK_TIMEDRDLOCK
  r = pthread_rwlock_timedrdlock(&rwlock, &abs_timeout); assert(r == 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
#endif
  fprintf(stderr, "Attempt to lock for writing recursively (not allowed).\n");
  r = pthread_rwlock_wrlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_wrlock(&rwlock); assert(r != 0);
  r = pthread_rwlock_unlock(&rwlock); assert(r == 0);
  r = pthread_rwlock_destroy(&rwlock); assert(r == 0);

  r = pthread_mutex_init(&mutex, NULL); assert(r == 0);
  fprintf(stderr, "Locking mutex via pthread_mutex_trylock().\n");
  r = pthread_mutex_trylock(&mutex); assert(r == 0);
  r = pthread_mutex_unlock(&mutex); assert(r == 0);
  fprintf(stderr, "Locking mutex via pthread_mutex_lock().\n");
  r = pthread_mutex_lock(&mutex); assert(r == 0);
  r = pthread_mutex_unlock(&mutex); assert(r == 0);
  fprintf(stderr, "Locking mutex via pthread_mutex_timedlock().\n");
#ifdef HAVE_PTHREAD_MUTEX_TIMEDLOCK
  r = pthread_mutex_timedlock(&mutex, &abs_timeout); assert(r == 0);
  r = pthread_mutex_unlock(&mutex); assert(r == 0);
#endif
  r = pthread_mutex_destroy(&mutex); assert(r == 0);

  return 0;
}

/**
 * @brief Try for cross lock (callable from fth thread ONLY).
 *
 * @param cross <IN> cross lock structure pointer
 * @param write <IN> Nonzero for write lock, zero for read lock
 */
int fthXTryLock(XLock_t *cross, int write) {

    // Wait for the fth lock to be free
    if (__sync_val_compare_and_swap(&cross->fthLock, 0, 1) != 0) {
        return (1);
    }

    // Now aquire the queing lock (should be free except for race)
    while (pthread_rwlock_trywrlock(&cross->qLock) != 0) {
        // Another fthread might be waiting for the lock - avoid race
        fthYield(0);                         // Avoid race between 2 fthreads
    }

     // Release the FTH lock now that we have the Q lock
    (void) __sync_fetch_and_sub(&cross->fthLock, 1);

    // Now we have the pthread queueing lock so everyone will wait behind us
    if (write) {
        if (pthread_rwlock_trywrlock(&cross->lock) != 0) { // Try to get it
            pthread_rwlock_unlock(&cross->qLock); // We failed - clean up
            return (2);                      // Try failed
        }
    } else {
        if (pthread_rwlock_tryrdlock(&cross->lock) != 0) { // Try to get it
            pthread_rwlock_unlock(&cross->qLock); // We failed - clean up
            return (2);                      // Try failed
        }
    }

    // Release the Q lock now that we have the full lock
    pthread_rwlock_unlock(&cross->qLock);

    return (0);

}

bool TRI_TryReadLockReadWriteLock (TRI_read_write_lock_t* lock) {
  int rc;

  rc = pthread_rwlock_tryrdlock(lock);

  return (rc == 0);
}

static void *tryrdlock(void *arg)
{
	int r = pthread_rwlock_tryrdlock(arg);
	if (r != EBUSY)
		t_error("tryrdlock for wrlocked lock returned %s, want EBUSY\n", strerror(r));
	return 0;
}

void test_multiple_readers(void) {
  fprintf(stderr, "test_multiple_readers\n");
  tell_thread_to_acquire_lock(READ_LOCK);

  /*
   * Now attempt to acquire the lock on the main thread.
   * Since they are both readers this should succeed.
   * Try with tryrdlock, rdlock and timedrdlock.
   */
  int rc = pthread_rwlock_tryrdlock(&g_rwlock);
  ASSERT_EQ(rc, 0);
  rc = pthread_rwlock_unlock(&g_rwlock);
  ASSERT_EQ(rc, 0);

  struct timespec t = { 0, 0 };
  rc = pthread_rwlock_timedrdlock(&g_rwlock, &t);
  ASSERT_EQ(rc, 0);
  rc = pthread_rwlock_unlock(&g_rwlock);
  ASSERT_EQ(rc, 0);

  rc = pthread_rwlock_rdlock(&g_rwlock);
  ASSERT_EQ(rc, 0);
  rc = pthread_rwlock_unlock(&g_rwlock);
  ASSERT_EQ(rc, 0);

  tell_thread_to_release_lock();
}

wi_boolean_t wi_rwlock_tryrdlock(wi_rwlock_t *lock) {
#ifdef WI_PTHREADS
	return (pthread_rwlock_tryrdlock(&lock->rwlock) == 0);
#else
	return true;
#endif
}

int PlatformRWTryRLock(RWLock lock) {
#ifndef WIN32
   pthread_rwlock_t *l = lock;
   return pthread_rwlock_tryrdlock(l);
#else
#endif
}

bool rw_mutex::impl::read_lock(double sec)
{
#ifdef __linux__
  if (!valid) return false;
#ifdef JUBATUS_UTIL_CONCURRENT_RWMUTEX_ERRORCHECK
  assert(holders_lk.lock()==true);
  assert(holders.count(thread::id())==0);
#endif

  bool result;
  if (sec<1e-9) {
    result = pthread_rwlock_tryrdlock(&lk);
  } else {
    timespec end=to_timespec(get_clock_time()+sec);
    result = pthread_rwlock_timedrdlock(&lk, &end)==0;
  }
#ifdef JUBATUS_UTIL_CONCURRENT_RWMUTEX_ERRORCHECK
  if (result) holders.insert(thread::id());
  assert(holders_lk.unlock()==true);
#endif
  return result;
#else
  return false;
#endif
}