Re: [Cppcms-users] Can I create an asynchronous socket connection from within an asynchronously mounted application?

[Artyom B. <art...@ya...>]

> From: Dietrich Müller <die...@gm...>
>To: cpp...@li... 
>Sent: Friday, October 12, 2012 6:32 PM
>Subject: [Cppcms-users] Can I create an asynchronous socket connection from within an asynchronously mounted application?
> 
>
>Hello, I try to create a socket connection from within my application and I seem to fail.
>I tried to setup the code like in this boost asio sample for an asynchronous http client (http://www.boost.org/doc/libs/1_51_0/doc/html/boost_asio/example/http/client/async_client.cpp) without the resolving part.
>Btw this resolver is pretty useful. Can it be integrated into booster aio?
>
>//the  call
>socket->async_connect(endpoint, std::bind(&ClassX::onConnected, this, std::placeholders::_1));
>
>//the first callback
>void ClassX::onConnected(const booster::system::error_code &e) {
>  if(!e)
>    //print some member of ClassX
>    //...
>    //and write something to the socket
>    socket->async_write(buff, std::bind(&ClassX::onWritten, this, std::placeholders::_1));
>}
>

Where buf's content resides? The memory areas pointed by buff should remain valid untill asynchronous write
operation is cimpleted.

Also if you want any help, show the full code



>//onWritten callback

>//onRead callback
>
>Now the problem is that as soon as I access a class member in any callback, the result is a segmentation fault.
>If I pass shared_from_this() and not this I get a assertion error in enable_shared_from_this.h:56 that p.get() == this is not true.


What is shared from this? I assume you try to make application with shared_from_this? You can't. Because
it is not created with shared_ptr, also if application exists all the time than you don't need to care
about shared from this stuff and use ordinary this.

>I think the problems are related to some synchronisation issues between the main and the application thread, as the synchronous calls work.
>Please give me some advice how I correctly use the socket in my application.



If you use asynchronous application than its thread and the event loop threads are the same.


**Next Time**

Show the full code.
Artyom Beilis
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