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Re: [PATCH 29/30] create_dir_entry(): allow the flag value to be passed as an argument

From
Junio C Hamano <gitster@pobox.com>
Date
Apr 25, 2012, 18:52 UTC
Message-ID
<xmqq62cnd4pv.fsf@junio.mtv.corp.google.com>
In-Reply-To
<xmqqfwbrd5ny.fsf@junio.mtv.corp.google.com>
Junio C Hamano <gitster@pobox.com> writes:
Show 30 quoted lines
> mhagger@alum.mit.edu writes:
>
>> diff --git a/refs.c b/refs.c
>> index 4eca965..869c9a7 100644
>> --- a/refs.c
>> +++ b/refs.c
>> @@ -231,18 +231,18 @@ static void clear_ref_dir(struct ref_dir *dir)
>>  }
>>  
>>  /*
>> + * Create a struct ref_entry object for the specified dirname and flag.
>>   * dirname is the name of the directory with a trailing slash (e.g.,
>>   * "refs/heads/") or "" for the top-level directory.
>>   */
>>  static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
>> -					  const char *dirname)
>> +					  const char *dirname, int flag)
>>  {
>>  	struct ref_entry *direntry;
>>  	int len = strlen(dirname);
>>  	direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
>>  	memcpy(direntry->name, dirname, len + 1);
>> -	direntry->flag = REF_DIR;
>> +	direntry->flag = flag;
>>  	direntry->u.subdir.ref_cache = ref_cache;
>
> As the returned structure will always represent a subdirectory and not a
> leaf node, i.e. you use u.subdir, I do not think it makes any sense to
> make it responsibility for the caller of this function to include
> REF_DIR in the value of the flag.

Forseeing a response "But but but REF_DIR will become OR of two variants", my complaint is still valid ;-) and it is the bit assignment you did in the final patch that is wrong. If you make REF_DIR (or not) to differenticate between ref_dir vs ref_value, and use another bit REF_INCOMPLETE to remember that you still need to find out the actual value of it, the the above can still be

	create_dir_entry(struct ref_cache *ref_cache, const char *dirname, int lazy)
	{
		...
		direntry->flag = REF_DIR | (lazy ? REF_INCOMPLETE : 0);
                ...
	}
I am OK with the following as well:
	create_dir_entry(struct ref_cache *ref_cache,
        		const char *dirname, unsigned extra)
	{
		...
		direntry->flag = REF_DIR | extra;
	}

The suggested bit assignment would also allow you to create ref_value leaf nodes, whose presence you know about (by iterating over readdir() results) but not their values yet (because you haven't opened and read them), by marking them with REF_INCOMPLETE to be extra lazy in the future, if necessary. I do not know if that much laziness buys us a lot, though ;-).

Previous: Junio C HamanoNext: Michael Haggerty
Message 33 of 37 in “Read loose references lazily”
  1. 00/30 Read loose references lazilymhagger@alum.mit.edu, Apr 24, 2012
  2. 01/30 get_ref_dir(): return early if directory cannot be readmhagger@alum.mit.edu, Apr 24, 2012
  3. 02/30 get_ref_dir(): use a strbuf to hold refnamemhagger@alum.mit.edu, Apr 24, 2012
  4. 03/30 get_ref_dir(): rename "base" parameter to "dirname"mhagger@alum.mit.edu, Apr 24, 2012
  5. 04/30 get_ref_dir(): require that the dirname argument ends in '/'mhagger@alum.mit.edu, Apr 24, 2012
  6. 05/30 refs.c: extract function search_for_subdir()mhagger@alum.mit.edu, Apr 24, 2012
  7. 06/30 get_ref_dir(): take the containing directory as argumentmhagger@alum.mit.edu, Apr 24, 2012
  8. 07/30 do_for_each_reflog(): return early on errormhagger@alum.mit.edu, Apr 24, 2012
  9. 08/30 do_for_each_reflog(): use a strbuf to hold logfile namemhagger@alum.mit.edu, Apr 24, 2012
  10. 09/30 do_for_each_reflog(): reuse strbuf across recursive function callsmhagger@alum.mit.edu, Apr 24, 2012
  11. 10/30 refs: wrap top-level ref_dirs in ref_entriesmhagger@alum.mit.edu, Apr 24, 2012
  12. Michael HaggertyApr 26, 2012
  13. 11/30 get_packed_refs(): return (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  14. 12/30 get_loose_refs(): return (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  15. 13/30 is_refname_available(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  16. 14/30 find_ref(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  17. 15/30 read_packed_refs(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  18. 16/30 add_ref(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  19. 17/30 find_containing_direntry(): use (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  20. 18/30 get_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  21. 19/30 get_ref_dir(): remove dirname argumentmhagger@alum.mit.edu, Apr 24, 2012
  22. 20/30 search_for_subdir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  23. 21/30 search_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  24. 22/30 add_entry(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  25. 23/30 do_for_each_ref_in_dirs(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  26. 24/30 do_for_each_ref_in_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  27. 25/30 sort_ref_dir(): take (ref_entry *) instead of (ref_dir *)mhagger@alum.mit.edu, Apr 24, 2012
  28. 26/30 struct ref_dir: store a reference to the enclosing ref_cachemhagger@alum.mit.edu, Apr 24, 2012
  29. 27/30 read_loose_refs(): rename function from get_ref_dir()mhagger@alum.mit.edu, Apr 24, 2012
  30. 28/30 read_loose_refs(): access ref_cache via the ref_dir fieldmhagger@alum.mit.edu, Apr 24, 2012
  31. 29/30 create_dir_entry(): allow the flag value to be passed as an argumentmhagger@alum.mit.edu, Apr 24, 2012
  32. Junio C HamanoApr 25, 2012
  33. Junio C HamanoApr 25, 2012
  34. Michael HaggertyApr 26, 2012
  35. 30/30 refs: read loose references lazilymhagger@alum.mit.edu, Apr 24, 2012
  36. Junio C HamanoApr 25, 2012
  37. Michael HaggertyApr 26, 2012

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