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On 02/12/2015 02:36 PM, Salvatore Orlando wrote:
> - I promised a non blocking algorithm for IP allocation. The one I was
> developing was based on specifying the primary key on the ip_requests
> table in a way that it would prevent two concurrent requests from
> getting the same address, and would just retry getting an address until
> the primary key constraint was satisfied. However, recent information
> emerged on MySQL galera's (*) data set [2] certification  clarified that
> this kind of algorithm would still result in a deadlock error from
> failed data set certification. It is worth noting that in this case a
> solution based on traditional compare-and-swap is not possible because
> concurrent requests would be inserting data at the same time. I am now
> working on an alternative solution, and I would like to first implement
> a PoC for it (so that I can prove it works).

Would something like the following work: insert the data in the DB, if
any error is got open a new transaction and try again ? enikanorov
proposed a retry mechanism here [1] . Can't wait for your POC! I had
been playing a while in the past to try to remove the locking from the
IP allocation, it's hard!

cheers,

Rossella


[1] https://review.openstack.org/#/c/149261/