Re: [gentoo-portage-dev] [PATCH] postsync: skip hooks and metadata-transfer when appropriate (bug 564988)

[Zac Medico]

On 11/06/2015 11:34 AM, Michał Górny wrote:
> On Fri, 6 Nov 2015 10:58:23 -0800
> Zac Medico <zmedico@g.o> wrote:
>
>> On 11/06/2015 10:39 AM, Michał Górny wrote:
>>> On Fri, 6 Nov 2015 09:24:15 -0800
>>> Zac Medico <zmedico@g.o> wrote:
>>>
>>>> On 11/06/2015 12:20 AM, Alexander Berntsen wrote:
>>>>> On 06/11/15 09:05, Michał Górny wrote:
>>>>>>>> I know nothing about the egencache stuff. Maybe Michał can
>>>>>>>> comment?
>>>>>> Michał finds this black magic. Trusts zmedico.
>>>>> I think it looks like it's probably supposed to be reasonable, perhaps.
>>>>>
>>>>> Maybe Brian can look at it. At least that way we'll have a lot of
>>>>> people that attempted understanding what's going on.
>>>>>
>>>>> Maybe we need a "Trusted-by:" line.
>>>>>
>>>>
>>>> Maybe it helps if I give some more context. At my workplace, we have
>>>> lots of scripts that call `emerge --sync private-work-repo` to ensure
>>>> that the current system has the latest changes from private-work-repo.
>>>> It can be annoying if it spends the bulk of its time calling hooks, even
>>>> though private-work-repo was already up-to-date:
>>>>
>>>>>>> Timestamps on the server and in the local repository are the same.
>>>>>>> Cancelling all further sync action. You are already up to date.
>>>>
>>>> So, we want to skip the hooks when repos are already up-to-date. In this
>>>> case, there's no point in calling hooks or updating the metadata cache.
>>>
>>> This is incorrect assumption. A change in master repo may trigger
>>> metadata cache update in slaved repo.
>>>
>>
>> Good point. I'll update it to account for this.
>
> Please don't. This is just one of the corner cases when it will fail.
> You can't assume any post-sync hook can be skipped if X or Y didn't
> change.

Can you give an example use case? It the sync operation did not change
anything, then how is it useful to run hooks?
-- 
Thanks,
Zac