[Kamailio-Users] ratelimit enhancements

[Daniel-Constantin Mierla]

Hello,

On 1/25/10 10:45 AM, marius zbihlei wrote:
> Daniel-Constantin Mierla wrote:
>> Hello,
>>
>> On 1/22/10 3:31 PM, Ovidiu Sas wrote:
>>> The way that the original module was written did not allow dynamic
>>> numbers of queues and pipes.
>>> I am using the ratelimit module to control incoming/outgoing traffic
>>> on specific trunks by invoking rate limitation based on pipes (by
>>> forcing a specific pipe).
>>> Choosing a specific pipe is up to the kamailio config designer (any
>>> type of operations ca be applied to the pvar before choosing a
>>> specific pipe, so IMHO it is pretty flexible as is right now - one can
>>> apply any regex operations to a pvar).
>>> Pipes and queues can be dynamically modified via mi commands.
>>> The major limitation of the module is the hard coded number of queues
>>> and pipes and the fact that dynamic changes to pipes and queues are
>>> not saved on restart.
>>>
>>> Loading the queues and pipes from a db will require a redesign of how
>>> the pipes and queues are stored internally.
>> yes, it is a hash table. A benefit of dynamic/dynamic names is you 
>> can simply use ip address as pipe name. Also strings tend to look 
>> more meaningful when coming back to a config after some time :-) .
>>
>> IIRC, one issue with the old design is using single lock for all 
>> pipes. The advantage was using static indexing, therefore faster 
>> access (still under one lock). The new one has a lock per slot, so 
>> there can be quite some parallelism of updates/checks, therefore 
>> overall could be same results, tending to be faster with old for low 
>> number of pipes and not so heavy traffic, better with lot of pipes 
>> and lot of traffic.
>>
>> On the other hand, I find useful what Marius proposed as new features.
>>
>> Cheers,
>> Daniel
>>
> Hello,
>
> I saw the pipelimit commit, and I am going to have a look to better 
> understand the design.

the changes are related to the storage engine (db and in memory) by 
allowing string names and dynamic add/remove pipes.
>   The first question is about the new pipelimit module...
> Does it require(as in it's a must) a working DB connection to get the 
> pipe configuration ? 

yes. That's why I said the old module should be kept and maybe export 
pipe algo in a lib ir from module.

I was thinking at some point more or less to your idea, to combine. But 
the complexity introduced to adapt from one to another does not pay the 
effort imo when comparing with having two modules clear targeting 
different sizes.

Most of the cases are as you say, but there are cases when the limit 
wants to be for each destination or source ip, and that can be 
controlled via other meanings, like dispatcher, lcr, etc... new ips can 
appear/disappear dynamically. Having static array with fixed indexing is 
not convenient.

I uploaded the module so people can discuss based on it. The sql to 
create the table is in one of the c files at the top.

Cheers,
Daniel
> Because this could be a problem for some systems, (like a light 
> stateless proxy in front of other machines) because this will mean the 
> requirement of loading a DB module.
> If there is indeed the need for a database, than I suggest that we 
> still allow cfg configuration , will the limitation that runtime 
> changes aren't permanent and are lost in case of a restart.
>
> Regarding the static indexing versus dynamic allocation of pipes, I 
> was thinking that most setups only need a few pipes and that number  
> doesn't change very often. With this in mind I was thinking about 
> combining the two approaches: start to a low number of pipes (16 for 
> example which is basicaly an array on the stack or continuous 
> allocation on the heap). In case of need of a 17th pipe double the 
> capacity (allocate a 32  continuous array on the heap ) and deep copy 
> the old 16 pipes (something that std::vector in c++ does when we alter 
> its capacity). This will add the advantage on using static indexing 
> but still provide with the new functionality of a variable number of 
> pipes.
>
> What do you think?
>
> Greetings,
> Marius
>
>
>
>
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-- 
Daniel-Constantin Mierla
* http://www.asipto.com/