xdiff/xprepare: use a smaller sample size for histogram diff

For histogram diff, we can afford a smaller sample size and thus a
poorer estimate of the number of lines, as the hash table (rhash) won't
be filled up/grown. This is safe as the final count of lines (xdf.nrecs)
will be updated correctly anyway by xdl_prepare_ctx().

This gives us a small boost in performance.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/xdiff/xutils.h b/xdiff/xutils.h
index 674a657b0..714719a89 100644
--- a/xdiff/xutils.h
+++ b/xdiff/xutils.h
@@ -33,7 +33,7 @@ void xdl_cha_free(chastore_t *cha);
 void *xdl_cha_alloc(chastore_t *cha);
 void *xdl_cha_first(chastore_t *cha);
 void *xdl_cha_next(chastore_t *cha);
-long xdl_guess_lines(mmfile_t *mf);
+long xdl_guess_lines(mmfile_t *mf, long sample);
 int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags);
 unsigned long xdl_hash_record(char const **data, char const *top, long flags);
 unsigned int xdl_hashbits(unsigned int size);