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

From
Michael Haggerty <mhagger@alum.mit.edu>
Date
Jun 9, 2016, 14:37 UTC
Message-ID
<57597F1A.3060400@alum.mit.edu>
In-Reply-To
<xmqq37oosya6.fsf@gitster.mtv.corp.google.com>
On 06/07/2016 07:29 PM, Junio C Hamano wrote:
Show 31 quoted lines
> Michael Haggerty <mhagger@alum.mit.edu> 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(&submodule, path, len);
>> -	refs = get_ref_store(submodule.buf);
>> -	strbuf_release(&submodule);
>> +	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.
Show 10 quoted lines
>> +		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
Previous: Junio C HamanoNext: Michael Haggerty
Message 35 of 67 in “Virtualization of the refs API”
  1. 00/38 Virtualization of the refs APIMichael Haggerty, Jun 3, 2016
  2. 01/38 resolve_gitlink_ref(): eliminate temporary variableMichael Haggerty, Jun 3, 2016
  3. 02/38 rename_ref_available(): add docstringMichael Haggerty, Jun 3, 2016
  4. Junio C HamanoJun 7, 2016
  5. Michael HaggertyJun 9, 2016
  6. Junio C HamanoJun 9, 2016
  7. 03/38 refs: rename struct ref_cache to files_ref_storeMichael Haggerty, Jun 3, 2016
  8. 04/38 refs: add a backend method structureMichael Haggerty, Jun 3, 2016
  9. 05/38 refs: create a base class "ref_store" for files_ref_storeMichael Haggerty, Jun 3, 2016
  10. Junio C HamanoJun 7, 2016
  11. René ScharfeJun 9, 2016
  12. Junio C HamanoJun 7, 2016
  13. Michael HaggertyJun 9, 2016
  14. Junio C HamanoJun 9, 2016
  15. Michael HaggertyJun 10, 2016
  16. Junio C HamanoJun 10, 2016
  17. Eric SunshineJun 10, 2016
  18. Michael HaggertyJun 10, 2016
  19. 06/38 add_packed_ref(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  20. 07/38 get_packed_ref(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  21. 08/38 resolve_missing_loose_ref(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  22. 09/38 {lock,commit,rollback}_packed_refs(): add files_ref_store argumentsMichael Haggerty, Jun 3, 2016
  23. 10/38 refs: add a transaction_commit() methodMichael Haggerty, Jun 3, 2016
  24. 11/38 refs: reorder definitionsMichael Haggerty, Jun 3, 2016
  25. 12/38 resolve_packed_ref(): rename function from resolve_missing_loose_ref()Michael Haggerty, Jun 3, 2016
  26. 13/38 resolve_gitlink_packed_ref(): remove functionMichael Haggerty, Jun 3, 2016
  27. 14/38 read_raw_ref(): take a (struct ref_store *) argumentMichael Haggerty, Jun 3, 2016
  28. 15/38 resolve_ref_recursively(): new functionMichael Haggerty, Jun 3, 2016
  29. 16/38 resolve_gitlink_ref(): implement using resolve_ref_recursively()Michael Haggerty, Jun 3, 2016
  30. Junio C HamanoJun 7, 2016
  31. Eric SunshineJun 14, 2016
  32. Michael HaggertyJun 16, 2016
  33. 17/38 resolve_gitlink_ref(): avoid memory allocation in many casesMichael Haggerty, Jun 3, 2016
  34. Junio C HamanoJun 7, 2016
  35. Michael HaggertyJun 9, 2016
  36. 18/38 resolve_gitlink_ref(): rename path parameter to submoduleMichael Haggerty, Jun 3, 2016
  37. 19/38 refs: make read_raw_ref() virtualMichael Haggerty, Jun 3, 2016
  38. 20/38 refs: make verify_refname_available() virtualMichael Haggerty, Jun 3, 2016
  39. 21/38 refs: make pack_refs() virtualMichael Haggerty, Jun 3, 2016
  40. Junio C HamanoJun 7, 2016
  41. Michael HaggertyJun 9, 2016
  42. 22/38 refs: make create_symref() virtualMichael Haggerty, Jun 3, 2016
  43. 23/38 refs: make peel_ref() virtualMichael Haggerty, Jun 3, 2016
  44. Junio C HamanoJun 7, 2016
  45. Michael HaggertyJun 9, 2016
  46. 24/38 repack_without_refs(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  47. 25/38 lock_raw_ref(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  48. 26/38 commit_ref_update(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  49. 27/38 lock_ref_for_update(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  50. 28/38 lock_ref_sha1_basic(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  51. 29/38 split_symref_update(): add a files_ref_store argumentMichael Haggerty, Jun 3, 2016
  52. 30/38 files_ref_iterator_begin(): take a ref_store argumentMichael Haggerty, Jun 3, 2016
  53. 31/38 refs: add method iterator_beginMichael Haggerty, Jun 3, 2016
  54. 32/38 refs: add methods for reflogMichael Haggerty, Jun 3, 2016
  55. 33/38 refs: add method for initial ref transaction commitMichael Haggerty, Jun 3, 2016
  56. 34/38 refs: add method for delete_refsMichael Haggerty, Jun 3, 2016
  57. Junio C HamanoJun 7, 2016
  58. Michael HaggertyJun 9, 2016
  59. 35/38 refs: add methods to init refs dbMichael Haggerty, Jun 3, 2016
  60. 36/38 refs: add method to rename refsMichael Haggerty, Jun 3, 2016
  61. 37/38 refs: make lock genericMichael Haggerty, Jun 3, 2016
  62. Junio C HamanoJun 7, 2016
  63. Michael HaggertyJun 9, 2016
  64. Michael HaggertyJun 9, 2016
  65. 38/38 refs: implement iteration over only per-worktree refsMichael Haggerty, Jun 3, 2016
  66. Duy NguyenJul 10, 2016
  67. Michael HaggertyJul 13, 2016

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