- strbuf_remove() in expand_name_field() is not exactly a good fit
for stripping a part at the end, _setlen() would do the same job
and is much cheaper.
- the open-coded loop to find the end of the string in
expand_name_field() can't beat an optimized strlen()
I used p0002-read-cache.sh to generate some performance data on the
cumulative impact:
100,000 files
Test HEAD~3 HEAD
---------------------------------------------------------------------------
read_cache/discard_cache 1000 times 14.08(0.03+0.09) 8.71(0.01+0.09) -38.1%
1,000,000 files
Test HEAD~3 HEAD
------------------------------------------------------------------------------
read_cache/discard_cache 1000 times 201.77(0.03+0.07) 149.68(0.04+0.07) -25.8%
Suggested by: Nguyễn Thái Ngọc Duy <pclo...@gmail.com>
Signed-off-by: Ben Peart <ben.pe...@microsoft.com>
---
read-cache.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/read-cache.c b/read-cache.c
index f768004617..f5e7c86c42 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1754,9 +1754,8 @@ static unsigned long expand_name_field(struct strbuf
*name, const char *cp_)
if (name->len < len)
die("malformed name field in the index");
- strbuf_remove(name, name->len - len, len);
- for (ep = cp; *ep; ep++)
- ; /* find the end */
+ strbuf_setlen(name, name->len - len);
+ ep = cp + strlen((const char *)cp);
strbuf_add(name, cp, ep - cp);
return (const char *)ep + 1 - cp_;
}
--
2.18.0.windows.1
