Re: [Cppcms-users] SSE keep-alive
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Re: [Cppcms-users] SSE keep-alive
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From: Artyom B. <art...@ya...> - 2013-04-02 11:26:49
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I don't really understand why do you have mutex... You may not write to the event stream from a thread that is not the event loop thread. If you want to notify the asynchronous SSE on anything you need to use cppcms::service::post() with a callback that would be executed in the event loop. Artyom Beilis -------------- CppCMS - C++ Web Framework: http://cppcms.com/ CppDB - C++ SQL Connectivity: http://cppcms.com/sql/cppdb/ >________________________________ > From: Christian Gmeiner <chr...@gm...> >To: Artyom Beilis <art...@ya...>; cpp...@li... >Sent: Tuesday, April 2, 2013 2:00 PM >Subject: Re: [Cppcms-users] SSE keep-alive > >2013/4/2 Christian Gmeiner <chr...@gm...>: >> 2013/4/1 Artyom Beilis <art...@ya...>: >>> >>> >>> ----- Original Message ----- >>>> From: Christian Gmeiner <chr...@gm...> >>>> To: cpp...@li... >>>> Cc: >>>> Sent: Monday, April 1, 2013 9:37 PM >>>> Subject: [Cppcms-users] SSE keep-alive >>>> >>>> HI all, >>>> >>>> I am trying to understand the keep-alive mechanism used in the SSE >>>> classes. I have the following problem: >>>> >>>> For test purposes I lowered the http timeout to 10 seconds, see >>>> keep-live is set to 1 second and the session timeout is set to 20 >>>> seconds. >>>> Now a client opens the sse stream /sse/get and gets a "ping" message. >>>> Now in theory every second the see keep-alive worker should do its >>>> work, but it >>>> looks like long_pollers_ and streamers_ are empty. void >>>> event_source::keep_alive(char const *comment) gets called every >>>> seconds but as long_pollers_ >>>> and streamers are empty no keep alive is send. >>>> There are two places where streamers_.insert is called: class >>>> post_send and void >>>> event_source::accept(booster::shared_ptr<cppcms::http::context> ctx). >>>> >>>> Maybe somebody can help me to under stand it! >>>> >>>> thanks >>>> -- >>>> Christian Gmeiner, MSc >>>> >>> >>> >>> >>> I don't really understand your setup. Does a user connected to the >>> thread get the keep alive messages (empty comment messages like :keep-alive) >>> or not? >>> >> >> A user _NEVER_ gets the keep alive message.. thats why I am asking :) >> >> I have added some debug to void event_source::keep_alive(char const *comment): >> http://dpaste.com/hold/1043987/ >> >> >> Here is an example log output: >> http://dpaste.com/hold/1044005/ >> >> >> As you can see after then last data transfer via SSE the keep_alive >> gets called, but does nothing. >> After 5 seconds the connection run into a timeout. >> >> >> My used config: >> >> { >> "service" : { >> "api" : "http", >> "ip" : "0.0.0.0", >> "port" : 8080 >> }, >> "http" : { >> "script" : "/tssw", >> "timeout" : 5, >> }, >> "session" : { >> "expire" : "renew", >> "timeout" : 15, >> "location" : "server", >> "gc" : 10, >> "server": { >> "storage":"memory" >> } >> }, >> "file_server" : { >> "enable" : true, >> "document_root" : "/opt/tssw/", >> "listing" : false, >> "alias" : [ >> { "url" : "/assets" , "path" : "/opt/tssw/" }, >> { "url" : "/downloads" , "path" : "/home/vis/" } >> ], >> }, >> "security" : { >> "csrf" : { >> "enable" : true >> }, >> "multipart_form_data_limit" : 1048576, >> "uploads_path" : "/home/vis/" >> }, >> "localization" : { >> "messages" : { >> "paths" : [ "/opt/tssw/locale" ], >> "domains" : [ "tssw" ] >> }, >> "locales" : [ "en.UTF-8", "de.UTF-8", "zh.UTF-8" ] >> }, >> "logging" : { >> "level" : "debug", >> "syslog" : { >> "enable" : true, >> "id" : "tssw", >> }, >> } >> } >> >> >> My used SSE application looks like: >> >> SSE::SSE(cppcms::service &srv) : cppcms::application(srv) >> { >> stream_ = sse::event_fifo::create(srv.get_io_service()); >> stream_->enable_keep_alive(1); >> >> dispatcher().assign("/get",&SSE::get,this); >> } >> >> void SSE::get() >> { >> stream_->accept(release_context()); >> } >> >> void SSE::enqueue(std::string const &event, std::string const &data) >> { >> stream_->push(event, data); >> } >> >> >> And my used event_fifo class: >> >> class event_fifo : public event_source { >> protected: >> event_fifo(booster::aio::io_service &srv) : >> event_source(srv) >> { >> } >> public: >> /// >> /// Create a queue of maximal size \a size, such that user that >> connects too late >> /// it would be able to receive at most \a size latest messages >> /// >> static booster::shared_ptr<event_fifo> create( >> booster::aio::io_service &srv) >> { >> booster::shared_ptr<event_fifo> p(new event_fifo(srv)); >> return p; >> } >> >> virtual void accept(booster::shared_ptr<cppcms::http::context> ctx) >> { >> // remove old messages >> mutex.lock(); >> while (messages_.empty() == false) >> { >> messages_.pop(); >> } >> mutex.unlock(); >> >> event_source::accept(ctx); >> >> // we need to send something that the EventSource on the client side >> // gets notified that the stream is open. >> push("welcome", "welcome"); >> } >> >> /// >> /// put a message into the fifo >> /// >> /// If \a send is false the messages are not dispatched >> /// immediately, you can dispatch them later by calling >> broadcast() or by calling push >> /// event with send=true >> /// >> void push(std::string const &data,bool send=true) >> { >> push(std::string(),data,send); >> } >> >> /// >> /// put a message into the fifo >> /// >> /// If \a send is false the messages are not dispatched >> /// immediately, you can dispatch them later by calling >> broadcast() or by calling push >> /// event with send=true >> /// >> void push(std::string const &event,std::string const &data,bool send=true) >> { >> message msg; >> msg.event = event; >> msg.data = data; >> >> mutex.lock(); >> messages_.push(msg); >> mutex.unlock(); >> >> if(send) >> broadcast(); >> } >> >> protected: >> bool on_sent(event_stream &es) >> { >> size_t last_id = es.last_integer_id(); >> size_t id = last_id; >> >> mutex.lock(); >> while (messages_.empty() == false) >> { >> id++; >> message &msg = messages_.front(); >> es.write(msg.data, id, msg.event); >> messages_.pop(); >> } >> mutex.unlock(); >> >> return true; >> } >> >> private: >> struct message { >> std::string event; >> std::string data; >> }; >> std::queue<message> messages_; >> booster::mutex mutex; >> }; >> >> } // namespace sse >> >> Oh... it is planed to have one SSE stream per session. >> If you need it I can provide you a simple demo application. >> > >Finally I got keep_alive working by changing on_send > > bool on_sent(event_stream &es) > { > bool something_send = false; > size_t last_id = es.last_integer_id(); > size_t id = last_id; > > mutex.lock(); > while (messages_.empty() == false) > { > id++; > message &msg = messages_.front(); > es.write(msg.data, id, msg.event); > messages_.pop(); > something_send = true; > } > mutex.unlock(); > > return something_send; > } > > >Now I am looking to prevent expiration of the user session. > >greets >-- >Christian Gmeiner, MSc > >------------------------------------------------------------------------------ >Own the Future-Intel(R) Level Up Game Demo Contest 2013 >Rise to greatness in Intel's independent game demo contest. Compete >for recognition, cash, and the chance to get your game on Steam. >$5K grand prize plus 10 genre and skill prizes. Submit your demo >by 6/6/13. http://altfarm.mediaplex.com/ad/ck/12124-176961-30367-2 >_______________________________________________ >Cppcms-users mailing list >Cpp...@li... >https://lists.sourceforge.net/lists/listinfo/cppcms-users > > > |
