[Freeswitch-users] UUID - how unique is it?

[Yossi Neiman]

RE: the per session uuid:  I've looked at the code recently, and I 
already don't recall the exact details.  :-)  However, if you have 
libuuid installed, it (apr and/or apr-util) defaults to using libuuid's 
functions and acts as nothing more than a shim.  I think part of the 
computation is based upon /dev/urandom and part on the timestamp and 
possibly a counter, but I might be merging things in my head incorrectly 
as that might be the non-libuuid segment of the code...  It's highly 
random, but as with any finite set, there is always a remote possibility 
of a collision.

The FS core UUID is instantiated at start-up of FS, so every time FS is 
restarted, it gets a new FS core UUID.

-Yossi

On 05/20/2013 07:18 AM, Michael Jerris wrote:
> The apr uuid stuff already has a portion of the uuid thats 
> per-instance. I've seen a lot of details in this thread that are not 
> accurate to my recollection of this code.  Has anyone actually dug in 
> and looked at it?  Its been a while by my recollection is each 
> instance gets a certain number of bits from random at startup, then 
> its a combination of time + counter.  The only collision possibility 
> would be the random at startup portion which would be much less likely 
> than getting struck by lightning.
>
> Mike
>
> On May 20, 2013, at 2:20 AM, Steven Ayre <steveayre at gmail.com 
> <mailto:steveayre at gmail.com>> wrote:
>
>> Sorry I meant to say with the daemon. (uuidd). That would be unique 
>> between multiple  instances too. If the time one is used its already 
>> unique to the server. But as I said, I'm not sure if that's the one 
>> FS uses.
>>
>> On Monday, May 20, 2013, Yossi Neiman wrote:
>>
>>     If you're running multiple FS instances, you could also use both
>>     the FS
>>     server UUID in addition to the session UUID together.  That'd mean
>>     storing more data but it would probably be on the order of winning a
>>     $500 million USD Powerball game twice within the same month...
>>
>>     -Yossi
>>
>>     _________________________________________________________________________
>>     Professional FreeSWITCH Consulting Services:
>>     consulting at freeswitch.org <javascript:;>
>>     http://www.freeswitchsolutions.com
>>     <http://www.freeswitchsolutions.com/>
>>
>>     
>>      </>
>>
>>     Official FreeSWITCH Sites
>>     http://www.freeswitch.org <http://www.freeswitch.org/>
>>     http://wiki.freeswitch.org <http://wiki.freeswitch.org/>
>>     http://www.cluecon.com <http://www.cluecon.com/>
>>
>>     FreeSWITCH-users mailing list
>>     FreeSWITCH-users at lists.freeswitch.org <javascript:;>
>>     http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>>     UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>>     http://www.freeswitch.org <http://www.freeswitch.org/>
>>
>> _________________________________________________________________________
>> Professional FreeSWITCH Consulting Services:
>> consulting at freeswitch.org <mailto:consulting at freeswitch.org>
>> http://www.freeswitchsolutions.com
>>
>> 
>> 
>>
>> Official FreeSWITCH Sites
>> http://www.freeswitch.org
>> http://wiki.freeswitch.org
>> http://www.cluecon.com
>>
>> FreeSWITCH-users mailing list
>> FreeSWITCH-users at lists.freeswitch.org
>> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
>> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
>> http://www.freeswitch.org
>
>
>
> _________________________________________________________________________
> Professional FreeSWITCH Consulting Services:
> consulting at freeswitch.org
> http://www.freeswitchsolutions.com
>
> 
> 
>
> Official FreeSWITCH Sites
> http://www.freeswitch.org
> http://wiki.freeswitch.org
> http://www.cluecon.com
>
> FreeSWITCH-users mailing list
> FreeSWITCH-users at lists.freeswitch.org
> http://lists.freeswitch.org/mailman/listinfo/freeswitch-users
> UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users
> http://www.freeswitch.org

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.freeswitch.org/pipermail/freeswitch-users/attachments/20130520/62b04eec/attachment.html