[OpenSIPS-Devel] RFC: new opensips design

[Bogdan-Andrei Iancu]

Hi Iñaki,

The whole idea is to concentrate all waits in a single point (like you 
do with a select while waiting for multiple TCP connections) - it is not 
a serial wait that may lead to idle time (because of the serialization), 
but a parallel approach where you are waiting in the same time for the 
termination of any I/O (reading a message from the net, a finished DNS, 
a DB response).

Just to give an example: let's assume we have 1 process

1) current design:
    time T - a message is read from network
    t+1 - a DB is invoked
       ---- idle ------
    t+3 - reply from DB
    t+4 - done with the message
    t+5 - read the next one

2) new design
    time T - a message is read from network (reactor gets indication 
from the network socket)
    t+1 - a DB is invoked (context is suspended and a new socket is 
added to the reactor for waiting the DB reply)
    t+2 - a second message is read from network (reactor gets again 
indication from the network socket)
    t+3 - second message is done
    t+4 - reply from DB (reactor get indication from the DB socket) -  
context is restored for the first message
    t+5 - done with the first message

So, i the same amount of time, you use all the time for computing 
instead of idle I/O and you can process more traffic.

Regards,
Bogdan


Iñaki Baz Castillo wrote:
> 2008/11/7 Bogdan-Andrei Iancu <bogdan at voice-system.ro>:
>   
>> Why? - I made a summary here -
>> http://www.opensips.org/pmwiki.php?n=Development.NewDesign#toc1
>>     
>
> Hi, I read:
>
> ----------
>  2.4  Asynchronous processing
>     * entire processing in core must be based on a asynchronous
> reactor - there will
>       be dead-time/idle because of I/O ops. The processing capacity
> will dramatically
>       increase.
> ----------
>
> AFAIK Reactor Pattern also waits in I/O opperations. I've read about
> Proactor Pattern that doesn't wait for them:
>   http://www.cs.wustl.edu/~schmidt/PDF/reactor-siemens.pdf
>   http://www.cs.wustl.edu/~schmidt/PDF/proactor.pdf
>
> Well, I have no idea about both of them XD
>
>