[sr-dev] [Fwd: Re: [Kamailio-Users] TCP supervisor process in Kamailio]

[Andrei Pelinescu-Onciul]

On Jul 09, 2009 at 13:50, Klaus Darilion <klaus.mailinglists at pernau.at> wrote:
> 
> 
> Andrei Pelinescu-Onciul schrieb:
> >On Jul 09, 2009 at 10:27, Klaus Darilion <klaus.mailinglists at pernau.at> 
> >wrote:
> >>
> >>Andrei Pelinescu-Onciul schrieb:
> >>>On Jul 07, 2009 at 15:53, Klaus Darilion <klaus.mailinglists at pernau.at> 
> >>>wrote:
> >>>>Hi Andrei!
> >>>>
> >>>>Do you think this is also relevant for sip-router's TCP implementation?
> >>>
> >>>The elevated priority for tcp_main is a good idea. I'll add a config
> >>>option for it (right now there are real time prio config options, but
> >>>only for the timer processes).
> >>>The rest of the paper does not apply to sr or recent ser versions
> >>>(fd cache was implemented long time ago, tcp timers are much better,
> >>>there is no known dealdock a.s.o.).
> >>Hi Andrei!
> >>
> >>How are incoming TCP messages handled in detail? e.g. if there is 
> >>incoming data on a TCP connection: which process reads the data and 
> >>constructs the SIP message? Is this the supervisor (which handles only 
> >>full messages over to the TCP workers) or a worker?
> >
> >It's the worker ("tcp_receiver" in sercmd ps output).
> >The supervisor ("tcp main") passes entire connections to the workers and
> >not messages.
> >When there is new data on a connection, tcp_main passes it to the
> >workers (round-robin). The worker that gets the connection will read
> >from it until it exhausts all the received data. After that it will start
> >a 5 s timeout. If no new data is received in this interval, it will
> >give-up the connection back to tcp_main. If new data is received, the
> >timeout will be extended (this timeout will keep connection with heavy
> >traffic in the same worker all the time allowing fast handling and it
> >will also accommodate traffic peaks).
> >
> >So a worker will read the data from the tcp connection, build the sip
> >message and run the routing script.
> 
> So, a worker will read from multiple connections concurrently and as 
> soon as it received a full SIP message from any of these connections, it 
> will process this single message. After message processing it continues 
> reading from the connections. E.g:
> 
>             |------
> tcpcon1---->|tcp_receiver
> tcpcon2---->|
>             |------
> 
> 1. data is available on con1: read the data, e.g. a half SIP message
> 2. data is available on con2: read the data, e.g. a half SIP message
> 3. data is available on con1: read the data, e.g. the second part of the 
> SIP message
> 4. a complete message is available (con1), process the message
> 5. data is available on con2: read the data, e.g. the second part of the 
> SIP message
> 6. a complete message is available (con2), process the message
> 
> Is this description correct?

Yes, it is.

Andrei