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

[Klaus Darilion]

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?

thanks
Klaus