Re: [PATCH v2 1/3] diffcore-pickaxe: remove unnecessary call to get_textconv()

Simon Ruderich <simon@ruderich.org> writes:

If I am reading the code correctly, it is has_changes(), which is used for "log -S" (not "log -G" that uses diff_grep()), that does the unnecessary get_textconv() unconditionally. The way diff_grep() divides the work to make fill_one() responsible for filling the textconv as necessary is internally consistent, and there is no unnecessary call.

Perhaps...

	The fill_one() function is responsible for finding and
	filling the textconv filter as necessary, and is called by
	diff_grep() function that implements "git log -G<pattern>".

	The has_changes() function calls get_textconv() for two
	sides being compared, before it checks to see if it was
	asked to perform the pickaxe limiting with the -S option.
	Move the code around to avoid this wastage.  After that,
	fill_one() is called to use the textconv.

	By adding get_textconv() to diff_grep() and relieving
	fill_one() of responsibility to find the textconv filter, we
	can avoid calling get_textconv() twice.

Explained that way, it makes me wonder why we cannot fix it the other way around, that is, not fetching textconv in has_changes() and instead letting fill_one() to find textconv as needed.

The answer is because has_changes() itself looks at the textconv.

But we have to wonder why it is so. diff_grep() short-circuits when the two sides are identical and has_changes() has a similar but different logic to check if the identical two sides are processed with the same textconv filter before saying this filepair is uninteresting.

Shouldn't that logic be unified as well?