From: Christian Couder Date: Wed, 17 Jan 2018 21:44:20 GMT Subject: Re: [PATCH v2 2/2] sha1_file: improve sha1_file_name() perfs Message-ID: In-Reply-To: <3cbace45-61df-3074-a48c-66c68c96d542@jeffhostetler.com> On Wed, Jan 17, 2018 at 9:37 PM, Jeff Hostetler wrote: > > > On 1/17/2018 12:54 PM, Christian Couder wrote: >> >> As sha1_file_name() could be performance sensitive, let's >> try to make it faster by seeding the initial buffer size >> to avoid any need to realloc and by using strbuf_addstr() >> and strbuf_addc() instead of strbuf_addf(). >> >> Helped-by: Derrick Stolee >> Helped-by: Jeff Hostetler >> Signed-off-by: Christian Couder >> --- >> sha1_file.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> >> diff --git a/sha1_file.c b/sha1_file.c >> index f66c21b2da..1a94716962 100644 >> --- a/sha1_file.c >> +++ b/sha1_file.c >> @@ -323,8 +323,14 @@ static void fill_sha1_path(struct strbuf *buf, const >> unsigned char *sha1) >> void sha1_file_name(struct strbuf *buf, const unsigned char *sha1) >> { >> - strbuf_addf(buf, "%s/", get_object_directory()); >> + const char *obj_dir = get_object_directory(); >> + size_t extra = strlen(obj_dir) + 1 + GIT_MAX_HEXSZ; > > Very minor nit. Should this be "+3" rather than "+1"? > One for the slash after obj_dir, one for the slash between > "xx/y[38]", and one for the trailing NUL. I think the trailing NUL is handled by strbuf_grow(), but I forgot about the / between "xx/y[38]", so I think it should be "+2" . Anyway I agree with Junio that using strbuf_grow() is not really needed. >> + if (extra > strbuf_avail(buf)) >> + strbuf_grow(buf, extra); >> + >> + strbuf_addstr(buf, obj_dir); >> + strbuf_addch(buf, '/'); >> fill_sha1_path(buf, sha1); >> }