fastrtps 网络端口的计算-以共享内存为例

原创于 2024-11-01 15:50:15 发布 · 500 阅读

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root用户，运行./fastrtps/examples/cpp/dds/HelloWorldExampleSharedMem/DDSHelloWorldExampleSharedMem publisher

创建以下文件描述符

$ ll /dev/shm/
总用量 2232
drwxrwxrwt  2 root root     260 11月  1 09:37 ./
drwxr-xr-x 19 root root    4640 10月  7 13:14 ../
-rw-rw-rw-  1 root root 2122272 11月  1 09:37 fastrtps_fb0567544297e750
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_fb0567544297e750_el
-rw-rw-rw-  1 root root   52400 11月  1 09:37 fastrtps_port7400
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_port7400_sl
-rw-rw-rw-  1 root root   52400 11月  1 09:37 fastrtps_port7410
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_port7410_el
-rw-rw-rw-  1 root root   52400 11月  1 09:37 fastrtps_port7411
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_port7411_el
-rw-rw-rw-  1 root root      32 11月  1 09:37 sem.fastrtps_port7400_mutex
-rw-rw-rw-  1 root root      32 11月  1 09:37 sem.fastrtps_port7410_mutex
-rw-rw-rw-  1 root root      32 11月  1 09:37 sem.fastrtps_port7411_mutex

yong用户，运行./fastrtps/examples/cpp/dds/HelloWorldExampleSharedMem/DDSHelloWorldExampleSharedMem subscriber

$ ll /dev/shm/
总用量 2344
drwxrwxrwt  2 root root     360 11月  1 09:38 ./
drwxr-xr-x 19 root root    4640 10月  7 13:14 ../
-rw-rw-rw-  1 root root 2122272 11月  1 09:37 fastrtps_fb0567544297e750
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_fb0567544297e750_el
-rw-rw-rw-  1 root root   52400 11月  1 09:37 fastrtps_port7400
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_port7400_sl
-rw-rw-rw-  1 root root   52400 11月  1 09:37 fastrtps_port7410
-rw-rw-rw-  1 root root   52400 11月  1 09:37 fastrtps_port7411
-rw-rw-rw-  1 root root       0 11月  1 09:37 fastrtps_port7411_el
-rw-rw-rw-  1 yong yong   52400 11月  1 09:37 fastrtps_port7412
-rw-rw-rw-  1 yong yong       0 11月  1 09:37 fastrtps_port7412_el
-rw-rw-rw-  1 yong yong   52400 11月  1 09:37 fastrtps_port7413
-rw-rw-rw-  1 yong yong       0 11月  1 09:37 fastrtps_port7413_el
-rw-rw-rw-  1 root root      32 11月  1 09:37 sem.fastrtps_port7400_mutex
-rw-rw-rw-  1 root root      32 11月  1 09:37 sem.fastrtps_port7410_mutex
-rw-rw-rw-  1 root root      32 11月  1 09:37 sem.fastrtps_port7411_mutex
-rw-rw-rw-  1 yong yong      32 11月  1 09:37 sem.fastrtps_port7412_mutex
-rw-rw-rw-  1 yong yong      32 11月  1 09:37 sem.fastrtps_port7413_mutex

fastrtps_fb0567544297e750_el独占锁只有pub才会创建
el是 RobustExclusiveLock 缩写
sl是RobustSharedLock 缩写

本程序默认 domainId =0、participantId=0
PG=Paricipant Id Gain 默认2
rtps端口计算规则:
应用首个进程的端口计算方法，eg:pid=1;每个进程端口默认+PG(2),eg：Pid=2

Traffic type	Well-known port expression	pid = 1	pId = 3
Metatraffic multicast	7400 + 250 * domainId	7400	7400
Metatraffic unicast	7400 + 250 * domainId + 10 + 2 * participantId	7410	7412
User multicast	7400 + 250 * domainId + 1
User unicast	7400 + 250 * domainId + 11 + 2 * participantId	7411	7413
fasrtps 代码：
RTPSParticipantImpl.cpp

bool RTPSParticipantImpl::createReceiverResources(
        LocatorList_t& Locator_list,
        bool ApplyMutation,
        bool RegisterReceiver)
{
    //略...
    for (auto it_loc = Locator_list.begin(); it_loc != Locator_list.end(); ++it_loc)
    {
        bool ret = m_network_Factory.BuildReceiverResources(*it_loc, newItemsBuffer, max_receiver_buffer_size);
        if (!ret && ApplyMutation)
        {
            uint32_t tries = 0;
            while (!ret && (tries < m_att.builtin.mutation_tries))
            {
                tries++;
                applyLocatorAdaptRule(*it_loc);
                ret = m_network_Factory.BuildReceiverResources(*it_loc, newItemsBuffer, max_receiver_buffer_size);
            }
        }
 
        ret_val |= !newItemsBuffer.empty();
 
        for (auto it_buffer = newItemsBuffer.begin(); it_buffer != newItemsBuffer.end(); ++it_buffer)
        {
            std::lock_guard<std::mutex> lock(m_receiverResourcelistMutex);
            //Push the new items into the ReceiverResource buffer
            m_receiverResourcelist.emplace_back(*it_buffer);
            //Create and init the MessageReceiver
            auto mr = new MessageReceiver(this, (*it_buffer)->max_message_size());
            m_receiverResourcelist.back().mp_receiver = mr;
            //Start reception
            if (RegisterReceiver)
            {
                m_receiverResourcelist.back().Receiver->RegisterReceiver(mr);
            }
        }
        newItemsBuffer.clear();
    }
 
    return ret_val;
}
 
Locator_t& RTPSParticipantImpl::applyLocatorAdaptRule(
        Locator_t& loc)
{
    // This is a completely made up rule
    // It is transport responsibility to interpret this new port.
    loc.port += m_att.port.participantIDGain;
    return loc;
}