Re: [RFC/ PATCH 1/5] tree-walk: do not stop when an error is detected

> Diane Gasselin <diane.gasselin@ensimag.imag.fr> writes:
>
>> When an error is detected, traverse_trees() is not stopped anymore.
>> The whole tree is traversed so that all the merging errors can be detected.
>
> A small worry is if we have some codepath that uses this function like
> this:
>
>    if (traverse trees finishes successfully) {
>        be happy, all is well;
>    } else {
>        attempt a different strategy to achieve
>        what we wanted to with traverse trees, if
>        it worked fine.
>    }
>
> In such a case, spending extra cycles in traverse-trees only to collect
> more errors would actively degrade performance in the "alternative
> implementation" codepath.  For "try 'quick but limited' version first, and
> if it doesn't work, try more elaborate version spending extra cycles"
> pattern to work well, the 'quick but limited' version needs to fail
> quickly without wasting extra cycles when it hits its limitation.  In the
> original code, we deliberately returned early upon seeing the first error
> exactly for this reason.
>
> I don't think of concrete examples offhand (fallbacks "merge -s resolve -s
> recursive" or "am -3" use come close, perhaps), though, so I may be
> worried needlessly in this case.  I honestly don't know offhand.
>
> With our attention focused only on UI issues, I however would agree that
> it makes a lot of sense to collect all errors and give them all to the
> user, especially because the extra cycles (compared to the current code)
> spent to do so is only in the error codepath.
>