Hey Boris, I believe you're right, there seems to be some incompatibility with post() and recursive event loops.
Joseph, I'm correct that you are calling WDialog::exec() from within a posted event ? I would like to reproduce this behaviour in a small test case. Regards, koen 2012/11/17 Nagaev Boris <bnag...@gmail.com>: > Hello! > > You are still using recursive event loop. Try not to use recursive > event loop with WServer::post(). Use WDialog->show() instead of > WDialog::exec(). Make sure to remove this WDialog, when it is closed. > > On Sat, Nov 17, 2012 at 4:13 AM, Joseph VanAndel <vanan...@ucar.edu> wrote: >> OK, I've modified my application to use wApp->bind() as shown below. >> >> Unfortunately, if a session dies, my application still crashes, as before: >> ================== >> terminate called after throwing an instance of 'Wt::WException' >> what(): doRecursiveEventLoop(): session was killed >> >> #5 0x00b3a183 in std::terminate() () from /usr/lib/libstdc++.so.6 >> #6 0x00b3a2c2 in __cxa_throw () from /usr/lib/libstdc++.so.6 >> #7 0x01767af8 in Wt::WebSession::doRecursiveEventLoop ( >> this=0xb5e3f850) >> at /usr/local/src/wt-3.2.3/src/web/WebSession.C:1051 >> #8 0x0143a7da in Wt::WDialog::exec (this=0x87fedb8, >> animation=...) at /usr/local/src/wt-3.2.3/src/Wt/WDialog.C:292 >> #9 0x08125562 in Login_GUI::confirm (this=0x87fed48, >> message=..., info=..., id=..., passwd=..., name=..., >> location=..., comment=...) at src/view/Login_GUI.cpp:75 >> #10 0x0816e002 in UIServer::showLogin (this=0x876aeb8, >> message=..., info=...) at src/view/UIServer.cpp:716 >> #11 0x0816f107 in UIServer::processStatusEvent (this=0x876aeb8, >> event=...) at src/view/UIServer.cpp:920 >> #12 0x0816f01c in UIServer::notifyStatusEvent (this=0x876aeb8) >> at src/view/UIServer.cpp:913 >> #13 0x08150537 in boost::_mfi::mf0<void, UIServer>::operator() ( >> this=0x87fed10, p=0x876aeb8) >> ====================== >> Although the session was killed, the WServer::post() call still invokes the >> callback, which eventually tries to post a WDialog. >> Wt::WebSession::doRecursiveEventLoop sees the session is dead, and throws an >> error. >> >> What I don't understand is how this could happen. WServer::post() schedules >> a call to >> WebController::handleApplicationEvent(), which checks whether the session >> corresponding to sessionID is alive before it invokes the session's callback. >> >> >> On Nov 13, 2012, at 9:30 AM, Joseph VanAndel <vanan...@ucar.edu> wrote: >> >>> Yes, although the logic is more complex, I can have the bound function >>> callback into the shared object to retrieve the data that I wanted to pass >>> to the bound function. >>> >>> For my application, I have a UIServer object (1 per session) and a >>> StatusServer (singleton), which relays status messages between sessions. >>> UIServer ctor calls >>> StatusServer::connect( this, >>> wApp->bind( boost::bind( &UIServer::notifyStatusEvent, this) )) >>> >>> StatusServer::postStatusEvent() will save a copy of the event in a >>> per-session queue. >>> and calls WServer::post(sessionid, callback), which indirectly calls >>> UIServer::notifyStatusEvent() >>> >>> UIServer::notifyStatusEvent() calls >>> StatusServer::getEvent() to retrieve the event, and call >>> UIServer::processStatusEvent() to handle the StatusEvent. >>> >>> >>> It would be quite helpful if <Wt_src>/examples/simplechat used >>> WApplication::bind(). >>> >>> I appreciate any examples, but examples that correctly handle real-world >>> situations, like browser sessions being closed are MUCH more useful. As >>> far as I can tell, because simplechat doesn't use WApplication::bind(), it >>> may not safely handle browser sessions that are closed. >>> >>> If I get the chance, I'll submit a rewritten simplechat example that uses >>> WApplication::bind(), but as they say "It won't be pretty!" >>> >>> >>> On Nov 13, 2012, at 4:44 AM, Koen Deforche wrote: >>> >>>> Hey Joseph, Rob, >>>> >>>> I guess you are both indicating a limitation: WApplication::bind() >>>> essentially returns a function without arguments, and thus all >>>> arguments already have to be bound before the call, which makes it >>>> useless when you want to pass on information from the external source. >>>> >>>> As a workaround, perhaps you can rather than 'push' new information, >>>> make the bound function 'poll' the information from the shared object >>>> ? >>>> >>>> I believe it should be possible to make WApplication::bind() work >>>> properly with any kind of function, including functions with free >>>> parameters -- although that requires a bit of digging into the >>>> meta-function possiblities of boost-ified c++... >>>> >>>> In any case, using WApplication::bind() later on is not very useful -- >>>> it needs to happen with the session lock and with the objects bound >>>> guaranteed to be alive at the moment of calling WApplication::bind(). >>>> >>>> Regards, >>>> koen >>>> >>>> ------------------------------------------------------------------------------ >>>> Monitor your physical, virtual and cloud infrastructure from a single >>>> web console. 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