Re: [PATCH 17/38] resolve_gitlink_ref(): avoid memory allocation in many cases

[Michael Haggerty]

On 06/07/2016 07:29 PM, Junio C Hamano wrote:
> Michael Haggerty  writes:
> 
>> If we don't have to strip trailing '/' from the submodule path, then
>> don't allocate and copy the submodule name.
> 
> Makes sense.
> 
>>  int resolve_gitlink_ref(const char *path, const char *refname, unsigned 
>> char *sha1)
>>  {
>> -int len = strlen(path);
>> -struct strbuf submodule = STRBUF_INIT;
>> +size_t len, orig_len = strlen(path);
>>  struct ref_store *refs;
>>  int flags;
>>  
>> -while (len && path[len-1] == '/')
>> -len--;
>> +for (len = orig_len; len && path[len - 1] == '/'; len--)
>> +;
>> +
>>  if (!len)
>>  return -1;
>>  
>> -strbuf_add(, path, len);
>> -refs = get_ref_store(submodule.buf);
>> -strbuf_release();
>> +if (len == orig_len) {
> 
> You can keep the original while (), without introducing orig_len,
> and check if path[len] is NUL, which would probably be an end result
> that is easier to read.

OK, I'll change it.

>> +refs = get_ref_store(path);
>> +} else {
>> +char *stripped = xmemdupz(path, len);
>> +
>> +refs = get_ref_store(stripped);
>> +free(stripped);
> 
> An alternative might be to add get_ref_store_counted() that takes
> (path, len) instead of NUL-terminated path, which does not look too
> bad looking at the state after applying all 38 patches.

This slash-stripping code was introduced in 2007 (0ebde32c87) and it's
not my priority to improve it as part of this patch series.

Michael

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Re: [PATCH 17/38] resolve_gitlink_ref(): avoid memory allocation in many cases

[Junio C Hamano]

Michael Haggerty  writes:

> If we don't have to strip trailing '/' from the submodule path, then
> don't allocate and copy the submodule name.

Makes sense.

>  int resolve_gitlink_ref(const char *path, const char *refname, unsigned char 
> *sha1)
>  {
> - int len = strlen(path);
> - struct strbuf submodule = STRBUF_INIT;
> + size_t len, orig_len = strlen(path);
>   struct ref_store *refs;
>   int flags;
>  
> - while (len && path[len-1] == '/')
> - len--;
> + for (len = orig_len; len && path[len - 1] == '/'; len--)
> + ;
> +
>   if (!len)
>   return -1;
>  
> - strbuf_add(, path, len);
> - refs = get_ref_store(submodule.buf);
> - strbuf_release();
> + if (len == orig_len) {

You can keep the original while (), without introducing orig_len,
and check if path[len] is NUL, which would probably be an end result
that is easier to read.

> + refs = get_ref_store(path);
> + } else {
> + char *stripped = xmemdupz(path, len);
> +
> + refs = get_ref_store(stripped);
> + free(stripped);

An alternative might be to add get_ref_store_counted() that takes
(path, len) instead of NUL-terminated path, which does not look too
bad looking at the state after applying all 38 patches.

> + }
> +
>   if (!refs)
>   return -1;
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