Hello Boris,
We have been keeping an eye on coroutines lately. We also saw a benefit for
local event loops, which would make displaying modal dialogs behave better
(when using them on the stack).
Wt is asynchronous in its http server, allows you to manually postpone the
response to a later point, but indeed Dbo calls are synchronous. For now we
recommend to increase the amount of threads if you notice that they're all
waiting for DB IO - that IO is usually not blocking for too long times so a
reasonable amount of threads should do the trick.
To be continued...
Best regards,
Wim.
2013/11/22 Nagaev Boris <bnag...@gmail.com>
> Hello!
>
> Because Wt::Dbo is synchronous, it often assumes most of time used by
> Wt worker thread. Using "classical" async approach (passing callbacks)
> is not convenient for Wt::Dbo. I propose change Wt event handlers into
> co-programs, so that async code may be written as if sync.
>
> C++11 provides lambdas and rvalue references, so Wt::Dbo API would not
> be changed. C++11 is already in Debian stable and MSVC 2012.
>
> Some changes required in Wt core. WApplication::notify (or some
> private Wt function, more general) should run as co-program, then all
> user code (not sure for WResource::handleRequest) would run inside
> co-program. Maybe this can be done be reimplementing
> WApplication::notify (without changes in Wt).
>
> New public methods: WIOService (or other class, maybe WApplication or
> WServer) provides method defer(function<void(const Error&)>). This
> methods "pauses" co-program, asynchronously execute function passed
> and resume current co-program.
>
> Co-programs may be implementedon top of boost_context or
> boost_coprogram. Boost_context is a dependency, so all this should be
> done as CMake feature, which can be switched off.
>
> References:
> https://bitbucket.org/gridem/synca Three HTTP-servers: sync, async
> (callbacks), synca (async + co-programs).
> http://habrahabr.ru/post/201826/ (in Russian) Overhead of co-programs
> was estimated as 5% for doing-nothing server, for servers with payload
> it should be less.
>
> Regards,
> Boris Nagaev
>
>
> ------------------------------------------------------------------------------
> Shape the Mobile Experience: Free Subscription
> Software experts and developers: Be at the forefront of tech innovation.
> Intel(R) Software Adrenaline delivers strategic insight and game-changing
> conversations that shape the rapidly evolving mobile landscape. Sign up
> now.
> http://pubads.g.doubleclick.net/gampad/clk?id=63431311&iu=/4140/ostg.clktrk
> _______________________________________________
> witty-interest mailing list
> witty-interest@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/witty-interest
>
------------------------------------------------------------------------------
Shape the Mobile Experience: Free Subscription
Software experts and developers: Be at the forefront of tech innovation.
Intel(R) Software Adrenaline delivers strategic insight and game-changing
conversations that shape the rapidly evolving mobile landscape. Sign up now.
http://pubads.g.doubleclick.net/gampad/clk?id=63431311&iu=/4140/ostg.clktrk
_______________________________________________
witty-interest mailing list
witty-interest@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/witty-interest
