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>
diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index ded7c32..a45e89b 100644
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -24,10 +24,6 @@
-#define XDL_GUESS_NLINES 256
-
-
-
long xdl_bogosqrt(long n) {
long i;
@@ -159,12 +155,12 @@
}
-long xdl_guess_lines(mmfile_t *mf) {
+long xdl_guess_lines(mmfile_t *mf, long sample) {
long nl = 0, size, tsize = 0;
char const *data, *cur, *top;
if ((cur = data = xdl_mmfile_first(mf, &size)) != NULL) {
- for (top = data + size; nl < XDL_GUESS_NLINES;) {
+ for (top = data + size; nl < sample;) {
if (cur >= top) {
tsize += (long) (cur - data);
if (!(cur = data = xdl_mmfile_next(mf, &size)))
