When the "log -S<pat>" switch counts occurrences of <pat> on the
pre-image and post-image of a change. As soon as we know we had e.g. 1
before and 2 now we can stop, we don't need to keep counting past 2.
With this change a diff between A and B may have different performance
characteristics than between B and A. That's OK in this case, since
we'll emit the same output, and the effect is to make one of them
better.
I'm picking a check of "one" first on the assumption that it's a more
common case to have files grow over time than not.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
---
diffcore-pickaxe.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 23362a23597..b7494fdf89c 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -68,7 +68,8 @@ static int diff_grep(mmfile_t *one, mmfile_t *two,
return ecbdata.hit;
}
-static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
+static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws,
+ unsigned int limit)
{
unsigned int cnt = 0;
unsigned long sz = mf->size;
@@ -88,6 +89,9 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
sz--;
}
cnt++;
+
+ if (limit && cnt == limit)
+ return cnt;
}
} else { /* Classic exact string match */
@@ -99,6 +103,9 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws)
sz -= offset + kwsm.size[0];
data += offset + kwsm.size[0];
cnt++;
+
+ if (limit && cnt == limit)
+ return cnt;
}
}
return cnt;
@@ -108,8 +115,8 @@ static int has_changes(mmfile_t *one, mmfile_t *two,
struct diff_options *o,
regex_t *regexp, kwset_t kws)
{
- unsigned int c1 = one ? contains(one, regexp, kws) : 0;
- unsigned int c2 = two ? contains(two, regexp, kws) : 0;
+ unsigned int c1 = one ? contains(one, regexp, kws, 0) : 0;
+ unsigned int c2 = two ? contains(two, regexp, kws, c1 + 1) : 0;
return c1 != c2;
}
--
2.31.1.639.g3d04783866f
