[sr-dev] git:master: acc: extended documentation for db_insert_mode parameter

[Daniel-Constantin Mierla]

On 16/04/14 11:24, Juha Heinanen wrote:
> Daniel-Constantin Mierla writes:
>
>>>>       Default value is 0 (no INSERT DELAYED).
>>> daniel,
>>>
>>> just to clarity, is there some relationship between INSERT DELAYED and
>>> async insert?
>> No.
> good.  so perhaps the comment on default value could be (no INSERT
> DELAYED nor async insert is used).
You can enhance the docs as you consider more clear -- the possible 
values are listed in the same section.
>
>> The mechanism behind async insert is as follow:
>> - the INSERT query is printed by the process that does the db operation
>> - the mysql module instead of sending the query to mysql server, clones
>> it in shared memory and sends it to the group of async workers
>> - one of the workers reads the task and sends the query to the database
>> server
> does there need to be a free async worker to serve the request or are
> the requests buffered so that the sender of the request is always
> immediately free to go on with other business?

The sender is immediately free. The request is queued in the internal 
socket (used to pass only the pointer to shared memory query) and will 
be handled by first async worker. In other words, the sender does like 
an 'udp send', but via a reliable socket.
>
>> To have the above working, the db_url is also cloned and sent to async
>> workers in order to identify the right connection to use. The first idle
>> async worker is receiving the task (it is kernel based, the same
>> mechanism used for many processes reading on the same UDP socket). You
>> have to specify the number of async workers via global parameter
>> async_workers:
>>
>> - http://www.kamailio.org/wiki/cookbooks/devel/core#async_workers
> that would have been my next question.  if someone only reads
> acc/README, it does not mention a need set async_workers > 0 in order to
> benefit from db_insert_mode=2.
You can add a note about this as well, if you put more content in the 
docs for this parameter.

Cheers,
Daniel

-- 
Daniel-Constantin Mierla - http://www.asipto.com
http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda