[PATCH 1 of 4 RFC] hook: have a generic hook for transaction opening

[Pierre-Yves David]

On 03/11/2015 09:17 AM, Ryan McElroy wrote:
> On 3/10/2015 9:15 AM, Pierre-Yves David wrote:
>>
>>
>> On 03/10/2015 06:04 AM, Augie Fackler wrote:
>>> On Tue, Mar 10, 2015 at 01:14:28AM -0700, Pierre-Yves David wrote:
>>>> This is RFC because I'm unhappy with the current names, but they are
>>>> going
>>>> to be bikesheded anyway. So I would like to get the topic moving and
>>>> code is
>>>> a good way to get that.
>>>>
>>>> The name in this series are:
>>>>
>>>> - txnopen (can abort)
>>>> - txnclosing (can abort)
>>>> - txnclosed
>>>
>>> I have no particular recommendations for better names (sorry), but I'm
>>> not sure what the merit of txnopen is given that we can't provide much
>>> information. A sample use case would help there, I guess.
>>
>> I've no sample usecase for txnopen, but it is very cheap to add and I
>> guess some extension//baroque setup will be very happy to have some
>> official way to control//record transaction opening.
>>
>> We could also move it a bit further to right after the transaction
>> have been openened (or add a new hooks for that). So that its easy to
>> add data in the transaction after it is open.
>>
>> Maybe we should have a hook for aborted transaction too. But yet again
>> I've no specific usecase in mind.
>>
>>> As for the others, we could probably rework some existing
>>> functionality to be examples. verify-after-push could be done as a
>>> txnclosing, and txnclosed could be used by the notify extension, so I
>>> see merit in both of those.
>>
>> txnclosing and txnclosed are -must-have-. None of the current hook
>> allow to catch a full transaction run with all its data. This is
>> extremely annoying for validation or synchronization.
>>
> The only idea I have on naming is "trx" instead of "txn", which is what
> I remember using back in my MySQL days. This is purely bikeshedding, and
> I feel bad about it, but you did ask... sooo...
>
> I prefer the "optimal" version you suggested with trx:
>
> - pretrxopen
> - pretrxclose
> - trxclosed

The thing is that we already have two hooks that use txn:

- pretxnchangegroup
- pretxncommit

another option is to go explicit and say pretransactionclose as the 
important part is "transaction"

Full list of currently documented hooks:

- hooks
- changegroup
- commit
- incoming
- outgoing
- post-<command>
- pre-<command>
- prechangegroup
- precommit
- prelistkeys
- preoutgoing
- prepushkey
- pretag
- pretxnchangegroup
- pretxncommit
- preupdate
- listkeys
- pushkey
- tag
- update




-- 
Pierre-Yves David