Re: [Cppcms-users] questions about chat example code

[CN <cn...@fa...>]

Thank you for your patience explaining all my questions!



Here I have one minor feedback regarding wording. Excerpt
from [1]http://cppcms.com/wikipp/en/page/cppcms_1x_application_lifetime
 follows:



"asynchronous applications are designed to handle multiple connections
simultaneously, and thus instead of being called in the thread pool per
each request, they run exclusively in the main [2]CppCMS Event Loop"



Since asynchronous applications run in main thread and are event
driven, shouldn't the word "simultaneously" be written as
"sequentially" instead? Because asynchronous applications do not accept
and process requests concurrently, requests must wait in line for
processing.  Asynchronous applications run in main thread and thus can
never handle multiple connections simultaneously. They handle one
connection at a time.



If I do not understand this framework correctly, corrections are
welcome and appreciated!



Regards,

CN





On Fri, Nov 22, 2013, at 10:02 PM, Artyom Beilis wrote:

(1) It is not a recursive call, the error: is function that eventually
calls read_data. It is callback/lambda expression it is not collected
on the stacl

(2) The client can't "reset connection" between these calls. The event
of "connection reset" is detected in the event loop. It is not
"multi-threading" it is event driven programming.

The reset connection can be called only once we exit this code snippet.

(3) As I mentioned before it is not multithreaded program.
Async-application run in the thread of the event loop.


I suggest read following sections:

[3]http://cppcms.com/wikipp/en/page/cppcms_1x_event_loop
[4]http://cppcms.com/wikipp/en/page/cppcms_1x_application_lifetime
[5]http://cppcms.com/wikipp/en/page/thread_safety


Artyom Beilis
--------------
CppCMS - C++ Web Framework:   http://cppcms.com/
CppDB - C++ SQL Connectivity:
http://cppcms.com/sql/cppdb/



On Wednesday, November 20, 2013 3:04 PM, CN <cn...@fa...>
wrote:

(1) ~/examples/chat/the_chat.html:

Lines 30 and 34 recursively call read_data(). Will these recursive
calls

eventually eat up stack memory? If they will, how to improve the code?



~/examples/chat/chat.cpp:



(2) Line 64:

waiters_.insert();

context->async_on_peer_reset()



If the client resets connection between the above two calls, will it

cause memory leak (although the leak is not serious because broadcast()

will call waiters_.clear() eventually)? If it will, does swapping the

orders of these two lines help?



context->async_on_peer_reset()

waiters_.insert();





(3) waiters_ manipulates its elements in get(), remove_context(), and

broadcast(). Do we need to implement lock mechanism on waiters_ to

ensure the code thread safe? If we do, how?



I would appreciate your understanding that I am absolutely not finding

fault with the example code. Rather, I am trying to learn as many as I

can from it.



Regards,

CN



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References

1. http://cppcms.com/wikipp/en/page/cppcms_1x_application_lifetime
2. http://cppcms.com/wikipp/en/page/cppcms_1x_event_loop
3. http://cppcms.com/wikipp/en/page/cppcms_1x_event_loop
4. http://cppcms.com/wikipp/en/page/cppcms_1x_application_lifetime
5. http://cppcms.com/wikipp/en/page/thread_safety
6. http://www.fastmail.fm/
7. http://pubads.g.doubleclick.net/gampad/clk?id=63431311&iu=/4140/ostg.clktrk
8. mailto:Cpp...@li...
9. https://lists.sourceforge.net/lists/listinfo/cppcms-users
  10. http://pubads.g.doubleclick.net/gampad/clk?id=63431311&iu=/4140/ostg.clktrk
  11. mailto:Cpp...@li...
  12. https://lists.sourceforge.net/lists/listinfo/cppcms-users

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