Hello,

On 6/13/12 11:47 AM, SamyGo wrote:
Hi again,
Nice to read the comment from you. Yes it could be a case - but this race condition will remain valid until I put some check on the insertion and lock the resource if one user is using that table, I forgot what they say in programming terms 

What do you suggest i do to avoid this since I may have customers with SIP trunks and I'd have to apply concurrent call limits to them using the same logic.

you can use lock functions from cfgutils to synchronize on a resource (like uid), should be better than locking an entire db table -- this will require that the updates will be done only from config, not by other applications.

Cheers,
Daniel

Regards,
Sammy.


On Wed, Jun 13, 2012 at 1:23 PM, Daniel-Constantin Mierla <miconda@gmail.com> wrote:
Hello,


On 6/12/12 12:01 PM, SamyGo wrote:
Thanks Sir,
Doing a static or even a run-time mapping of same UID calls to destination server is what I thought about this type of case almost an year ago. 

What I am thinking is : create a table for UID/Destination Mapping; for a unique UID see if there is any destination in that table. If it exists just jump to that server directly. If no UID/destination entry is found for that UID then invoke Dispatcher; select destination, make call to it, and store this in UID/destination map table !!

Let me know if there could be any improvement in this.

can be a solution, indeed. You may have a race if that user does calls in parallel first time and different destinations are selected -- not sure it is the case for you.

Cheers,
Daniel



Thanks
Best Regards,
Sammy G.

On Tue, Jun 12, 2012 at 2:43 PM, Daniel-Constantin Mierla <miconda@gmail.com> wrote:
Hello,

if you are using integer UID, I would suggest you use modulo operation to select the destination address -- this will require config operations only.

Another option you can map an UID to a dispatcher set id (e.g., via mtree or htable) and then you can do the alg 8.

Cheers,
Daniel


On 6/7/12 1:37 PM, SamyGo wrote:
Hi again,
yes my scenario is quiet simple. I've  lots of users  and groups of those users are defined by UIDs, one UID means 70 users of one client whereas other UID could've 3 users of another client. 
So what I am trying to implement here is that calls from one same UID are always routed to exactly one same destination server. That'll help in issues like call-parking, call-pickup, conference calls etc.

I hope I've explained the scenario in simpler terms here.

Regards,
Sammy Go.


On Thu, Jun 7, 2012 at 4:20 PM, Daniel-Constantin Mierla <miconda@gmail.com> wrote:
Hello,

that hash function is intended for hashing alpha-numeric usernames and has a fair distribution for such cases.

I don't think is good for hashing numbers, at the end of a day, a number is already like a hash code. You can use in the config file modulo operation to select a particular destination based on a number.

Maybe if you explain what is your target to implement, we can provide the right hints to do it.

Cheers,
Daniel


On 6/6/12 6:09 PM, SamyGo wrote:
Sorry for late reply: this wasn't very helpful. I think Hashing algo code needs to get bit smarter. If there is any possibility can you please let me know. !
 

On Mon, Jun 4, 2012 at 3:33 PM, Daniel-Constantin Mierla <miconda@gmail.com> wrote:
To make the life easier to spot the hash code in such case, I just committed a small patch to print it for alg 7:

http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=83a558fbad700198a8667ef01f756269d7e2c310

Should be easy to backport if other version is used.

Cheers,
Daniel


On 6/4/12 12:23 PM, Carsten Bock wrote:
It's hard to say, most likely not. You find the used hash-function here:

 841 unsigned int ds_get_hash(str *x, str *y)
http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=blob;f=modules_k/dispatcher/dispatch.c;h=ae0c51b122d34e29b3474957a64b24ff492cfcd5;hb=HEAD

It was originally implemented to distribute usernames to servers,
which worked fine.

Carsten

2012/6/4 SamyGo <govoiper@gmail.com>:
Thanks Sir,

Thats what I expected. Do you think this will change if I use only two
values with huge difference in each other, lets say {26000,29000} ?

Regards,
Sammy

On Mon, Jun 4, 2012 at 3:05 PM, Carsten Bock <carsten@ng-voice.com> wrote:
Hi,

this functionality uses a generic "hash" function to generate an
Integer-Value of the PVAR and then reduces this to the number hosts in
your destination set.
If you have only using two different values of the PVAR and only two
hosts in the dispatcher list, it can likely happen, that the same host
is choosen. You should try a wider range of values for your PVAR...
(e.g. try 1000 different values), then you should see a distribution.

Carsten

2012/6/4 SamyGo <govoiper@gmail.com>:
Hi,

No, nothing at all. I haven't went too deep into debug logs but no
internal
error was appearing. Everything was as calm as ever and I only get one
destination uri.

So maybe what I'm getting from your email is that , for this to work the
way
I expect is to have more unique and random values in my hash_pvar to get
the
required functionality.

Thanks once again,
BR
SG

On Mon, Jun 4, 2012 at 11:52 AM, Daniel-Constantin Mierla
<miconda@gmail.com> wrote:
Hello,

do you get any errors in the log?

Be aware that hash functions may return same code for different input
values. A hash function is guaranteed to return same code for same
input
value, but there can be collisions of codes for different values.

Cheers,
Daniel


On 6/3/12 3:41 PM, SamyGo wrote:

Hello,

I'm having trouble using algorithm 7 in dispatcher module. Here is my
kamailio version. The problem is that despite multiple dispatcher
entries
corresponding to one set all calls go only to only one destination.


[root@control1 ~]# kamailio -V
version: kamailio 3.2.3 (x86_64/linux) 59f87e
flags: STATS: Off, USE_IPV6, USE_TCP, USE_TLS, TLS_HOOKS,
USE_RAW_SOCKS,
DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC,
DBG_QM_MALLOC, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE,
USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16,
MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 4MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: 59f87e
compiled on 18:04:08 Apr 19 2012 with gcc 4.1.2
[root@control1 ~]#

Here is the dipacther module params.



# ------- Load-balancer params ------
modparam("dispatcher", "db_url", DBURL)
modparam("dispatcher", "table_name", "dispatcher")
modparam("dispatcher", "setid_col", "setid")
modparam("dispatcher", "destination_col", "destination")
modparam("dispatcher", "force_dst", 1)
modparam("dispatcher", "flags", 3)
modparam("dispatcher", "dst_avp", "$avp(i:271)")
modparam("dispatcher", "cnt_avp", "$avp(i:273)")
modparam("dispatcher", "ds_ping_from", "sip:proxy@109.XXX.2XX.XX")
modparam("dispatcher", "ds_ping_interval",15)
modparam("dispatcher", "ds_probing_mode", 1)
modparam("dispatcher", "ds_ping_reply_codes",
"class=2;code=403;code=404;code=484;class=3")
modparam("dispatcher", "hash_pvar", "$avp(i:274)")
modparam("dispatcher", "ds_hash_size", 9)
modparam("dispatcher", "ds_hash_initexpire", 60)



Below is the function call based on avp(i:274)



avp_db_query("select uid from uid_did_map where accountcode =
'$fU'","$avp(i:274)");
xlog("L_INFO","$rm from $fu (IP:$si:$sp) ---------
UID:'$avp(i:274)-----------'\n");
        ds_load_update();
        if(!ds_select_dst("1","7")) {
                        sl_send_reply("500", "No destination
available");
                        xlog("route[MAIN] : $rm : No destinations
available for $rd");
                        exit;
        }


I'm getting two different values for avp(i:274) {26,29} but the
destination are not hashed on its base.

Please help.

Regards,
Sammy G.



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Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 -
http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 -
http://asipto.com/u/kpw




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_______________________________________________
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
sr-users@lists.sip-router.org
http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users




--
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw




_______________________________________________
SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
sr-users@lists.sip-router.org
http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users


-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw




-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw




-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw




-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda
Kamailio Advanced Training, Seattle, USA, Sep 23-26, 2012 - http://asipto.com/u/katu
Kamailio Practical Workshop, Netherlands, Sep 10-12, 2012 - http://asipto.com/u/kpw