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From: Christian Couder <christian.couder@gmail.com>
To: Jeff Hostetler <git@jeffhostetler.com>
Cc: git <git@vger.kernel.org>, Junio C Hamano <gitster@pobox.com>,
	Jeff Hostetler <jeffhost@microsoft.com>,
	Jonathan Tan <jonathantanmy@google.com>,
	Derrick Stolee <stolee@gmail.com>, Kevin Daudt <me@ikke.info>,
	Christian Couder <chriscool@tuxfamily.org>
Subject: Re: [PATCH v2 2/2] sha1_file: improve sha1_file_name() perfs
Date: Wed, 17 Jan 2018 22:44:20 +0100	[thread overview]
Message-ID: <CAP8UFD16OLcmATtr8wg7KcnyUJJLYv5+8n+ygSZEOUbHMTgopQ@mail.gmail.com> (raw)
In-Reply-To: <3cbace45-61df-3074-a48c-66c68c96d542@jeffhostetler.com>

On Wed, Jan 17, 2018 at 9:37 PM, Jeff Hostetler <git@jeffhostetler.com> 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 <stolee@gmail.com>
>> Helped-by: Jeff Hostetler <git@jeffhostetler.com>
>> Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
>> ---
>>   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);
>>   }

      parent reply	other threads:[~2018-01-17 21:44 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-17 17:54 [PATCH v2 1/2] sha1_file: remove static strbuf from sha1_file_name() Christian Couder
2018-01-17 17:54 ` [PATCH v2 2/2] sha1_file: improve sha1_file_name() perfs Christian Couder
2018-01-17 20:37   ` Jeff Hostetler
2018-01-17 20:54     ` Junio C Hamano
2018-01-17 22:27       ` Jeff King
2018-01-17 21:44     ` Christian Couder [this message]

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