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POOBSE and Boost.Asio: Threaded async UDP server with deadline_timer on the same io_service
 

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  1. POOBSE and Boost.Asio: Threaded async UDP server with deadline_timer on the same io_service
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    <ul> <li><strong>Platform</strong>: Windows 7 Professional 64 bit</li> <li><strong>Compiler</strong>: VS2010 Express</li> <li><strong>Boost</strong>: Version 1.49</li> <li><strong>Plugin System</strong>: OBSE 20 (for the Oblivion game by Bethesda)</li> </ul> <p>I have a class based upon the async udp examples. I run the io service itself as a thread. Here is the code for the class:</p> <pre><code> // udp buffer queues extern concurrent_queue&lt;udp_packet&gt; udp_input_queue; // input from external processes extern concurrent_queue&lt;udp_packet&gt; udp_output_queue; // output to external processes using boost::asio::ip::udp; class udp_server { public: udp_server(boost::asio::io_service&amp; io_service, short port) : io_service_(io_service), socket_(io_service_, udp::endpoint(boost::asio::ip::address_v4::from_string(current_address), port))//, // udp::v4() { // start udp receive socket_.async_receive_from( boost::asio::buffer(recv_buf), sender_endpoint_, boost::bind(&amp;udp_server::handle_receive_from, this, boost::asio::placeholders::error, boost::asio::placeholders::bytes_transferred)); send_timer_ = NULL; } ~udp_server(){ io_service_.stop(); if(send_timer_){ send_timer_-&gt;cancel(); delete send_timer_; } } void start(){ // start send timer send_timer_ = new boost::asio::deadline_timer(io_service_, boost::posix_time::milliseconds(500)); send_timer_restart(); } void handle_send_to(const boost::system::error_code&amp; error, size_t bytes_recvd); void handle_receive_from(const boost::system::error_code&amp; error, size_t bytes_recvd); //void handle_send_timer(const boost::system::error_code&amp; error); void handle_send_timer(); void send_timer_restart(); void stop() { io_service_.stop(); } private: boost::asio::io_service&amp; io_service_; udp::socket socket_; udp::endpoint sender_endpoint_; std::vector&lt;udp::endpoint&gt; clientList; //std::auto_ptr&lt;boost::asio::io_service::work&gt; busy_work; udp_buffer recv_buf; boost::asio::deadline_timer* send_timer_; }; </code></pre> <p>Now I instantiate the class and thread like this:</p> <pre><code> udp_server *udp_server_ptr=NULL; boost::asio::deadline_timer* dlineTimer=NULL; static void PluginInit_PostLoadCallback() { _MESSAGE("NetworkPipe: PluginInit_PostLoadCallback called"); if(!g_Interface-&gt;isEditor) { _MESSAGE("NetworkPipe: Starting UDP"); udp_server_ptr = new udp_server(io_service, current_port); //dlineTimer = new boost::asio::deadline_timer(io_service); udp_thread = new boost::thread(boost::bind(&amp;boost::asio::io_service::run, &amp;io_service)); // _MESSAGE("NetworkPipe: UDP Started"); NetworkPipeEnable = true; } else { _MESSAGE("NetworkPipe: Running in editor, not starting UDP"); } } </code></pre> <p>Now notice that dlineTimer is commented out above. If I enable that it ceases to function. The only way I can get the dlineTimer to function with this io service is to create it during the <code>udp_server::handle_receive_from</code> call. I think this is because it is running inside the other thread. So for some reason the <code>deadline_timer</code> object does not like being created outside the thread it needs to run inside.</p> <p>Now, in order to communicate to the main thread I use <code>concurrent_queue</code> objects. So these allow me to send messages in and out of the thread pretty simply. I could theoretically run the <code>dlineTimer</code> inside its own thread and use the output queue to manage its activity. However, I like the simplicity of having is in the same thread as the <code>udp_server</code>. For instance the <code>udp_server</code> object keeps track of clients in a vector. When the <code>deadline_timer</code> expires I cycle through the known clients and send them messages. Then I restart the timer. This makes my response independent of the udp packets that are sent to the server. So when packets arrive they are put on a queue for another part of the process. Then later data is placed on the output queue and the <code>deadline_timer</code> processes those responses and sends them to the appropriate clients.</p> <p>So my main question is: </p> <p>How do I more cleanly create the <code>deadline_timer</code> object using the same thread and same <code>io_service</code> as the <code>udp_server</code> object?</p>
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    1. USDemolishun
    1. USDemolishun
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    1. COAt a glance, I can't see any problem with the way you create the `deadline_timer`. Perhaps, the problem is in some other place that you don't show? What do you mean by saying "it ceases to function"? What behavior do you observe exactly?
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      1. POOBSE and Boost.Asio: Threaded async UDP server with deadline_timer on the same io_service
      1. USIgor R.
    2. COyour _MESSAGE macro invokes undefined behavior because identifiers beginning with an underscore and a capital letter are [reserved for the implementation](http://stackoverflow.com/a/228797/283302).
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      1. POOBSE and Boost.Asio: Threaded async UDP server with deadline_timer on the same io_service
      1. USSam Miller
    3. COWhat platform? Note that Windows platforms use a [thread per io_service to emulate asynchroncity](http://www.boost.org/doc/libs/release/doc/html/boost_asio/overview/implementation.html) for deadline_timer objects. This may be related as you seem to be writing some sort of plugin.
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      1. POOBSE and Boost.Asio: Threaded async UDP server with deadline_timer on the same io_service
      1. USSam Miller
 

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