On Wed, Apr 16, 2014 at 04:15:19PM +0200, Stepan Kasal wrote:
> From: Jean-Jacques Lafay <jeanjacques.lafay@xxxxxxxxx>
> Date: Sat, 10 Nov 2012 18:36:10 +0100
>
> In large repos, the recursion implementation of contains(commit,
> commit_list) may result in a stack overflow. Replace the recursion with
> a loop to fix it.
>
> This problem is more apparent on Windows than on Linux, where the stack
> is more limited by default.
I think this is a good thing to be doing, and it looks mostly good to
me. A few comments:
> -static int contains_recurse(struct commit *candidate,
> +/*
> + * Test whether the candidate or one of its parents is contained in the list.
> + * Do not recurse to find out, though, but return -1 if inconclusive.
> + */
> +static int contains_test(struct commit *candidate,
> const struct commit_list *want)
Can we turn this return value into
enum {
CONTAINS_UNKNOWN = -1,
CONTAINS_NO = 0,
CONTAINS_YES = 1,
} contains_result;
to make the code a little more self-documenting?
> static int contains(struct commit *candidate, const struct commit_list *want)
> {
> - return contains_recurse(candidate, want);
> + struct stack stack = { 0, 0, NULL };
> + int result = contains_test(candidate, want);
> +
> + if (result >= 0)
> + return result;
Then this can become:
if (result != CONTAINS_UNKNOWN)
return result;
> + if (!parents) {
> + commit->object.flags = UNINTERESTING;
> + stack.nr--;
> + }
Shouldn't this be "|=" when setting the flag?
> + /*
> + * If we just popped the stack, parents->item has been marked,
> + * therefore contains_test will return a meaningful 0 or 1.
> + */
> + else switch (contains_test(parents->item, want)) {
> + case 1:
> + commit->object.flags |= TMP_MARK;
> + stack.nr--;
> + break;
> + case 0:
> + entry->parents = parents->next;
> + break;
> + default:
> + push_to_stack(parents->item, &stack);
> + break;
> + }
And if we have an enum, this switch() becomes more readable (the
"default" here threw me off initially, because it is actually just
looking for "-1").
> +>expect
> +# ulimit is a bash builtin; we can rely on that in MinGW, but nowhere else
> +test_expect_success MINGW '--contains works in a deep repo' '
> + ulimit -s 64
It would be nice to test this on Linux.
Can we do something like:
test_lazy_prereq BASH 'bash --version'
test_expect_success BASH '--contains works in a deep repo' '
... setup repo ...
bash -c "ulimit -s 64 && git tag --contains HEAD" >actual &&
test_cmp expect actual
'
As a bonus, then our "ulimit" call does not pollute the environment of
subsequent tests.
-Peff
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