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From: Junio C Hamano <gitster@pobox•com>
To: Duy Nguyen <pclouds@gmail•com>
Cc: "brian m. carlson" <sandals@crustytoothpaste•net>,
	Michael Haggerty <mhagger@alum•mit.edu>,
	"Kyle J. McKay" <mackyle@gmail•com>,
	Git Mailing List <git@vger•kernel.org>,
	Andreas Schwab <schwab@linux-m68k•org>
Subject: Re: [PATCH v2 01/10] Define a structure for object IDs.
Date: Thu, 12 Mar 2015 11:44:31 -0700	[thread overview]
Message-ID: <xmqqa8zi2gz4.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <xmqqwq2m2hwf.fsf@gitster.dls.corp.google.com> (Junio C. Hamano's message of "Thu, 12 Mar 2015 11:24:32 -0700")

Junio C Hamano <gitster@pobox•com> writes:

> Duy Nguyen <pclouds@gmail•com> writes:
>
>> This may or may not fall into the "mix different hash functions"
>> category. In pack files version 4, trees are encoded to point to other
>> trees or blobs by a (pack, offset) tuple. It would be great if the new
>> object_id could support carrying this kind of object id around because
>> it could help reduce object lookup cost a lot. (pack, offset) can be
>> converted back to SHA-1 so no info is lost and hashcmp() can compare
>> (pack, tuple) against an SHA-1 just fine.
>
> You mean "if it came in <pack, offset> format, convert it down to
> <sha1> until the last second that it is needed (e.g. need to put
> that in a tree object in order to compute the object name of the
> containing tree object)"?

Sorry, obviously I meant "do not convert until the last second".

> To me, <pack, offset> information smells to belong more to a "struct
> object" (or its subclass) as an optional annotation---when a caller
> is asked to parse_object(), you would bypass the sha1_read_file()
> that goes and looks the object name up from the list of pack .idx
> and instead go there straight using that annotation.

  reply	other threads:[~2015-03-12 18:44 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-07 23:23 [PATCH v2 00/10] Use a structure for object IDs brian m. carlson
2015-03-07 23:23 ` [PATCH v2 01/10] Define " brian m. carlson
     [not found]   ` <CEA07500-9F47-4B24-AD5D-1423A601A4DD@gmail.com>
2015-03-11 22:08     ` brian m. carlson
2015-03-12  0:26       ` Junio C Hamano
2015-03-12  9:34         ` brian m. carlson
2015-03-12 10:28         ` Michael Haggerty
2015-03-12 10:46           ` brian m. carlson
2015-03-12 11:16             ` Duy Nguyen
2015-03-12 18:24               ` Junio C Hamano
2015-03-12 18:44                 ` Junio C Hamano [this message]
2015-03-13  0:58                 ` Duy Nguyen
2015-03-13  6:03                   ` Junio C Hamano
2015-03-14 11:49                     ` Duy Nguyen
2015-03-14 22:19                       ` Junio C Hamano
2015-03-15  0:17                         ` Duy Nguyen
2015-03-15  2:32                           ` Junio C Hamano
2015-03-07 23:23 ` [PATCH v2 02/10] Define utility functions " brian m. carlson
2015-03-08  9:57   ` Duy Nguyen
2015-03-08 14:48     ` brian m. carlson
2015-03-11 12:44   ` Michael Haggerty
2015-03-07 23:23 ` [PATCH v2 03/10] bisect.c: convert leaf functions to use struct object_id brian m. carlson
2015-03-07 23:23 ` [PATCH v2 04/10] archive.c: convert " brian m. carlson
2015-03-11 14:20   ` Michael Haggerty
2015-03-11 22:12     ` brian m. carlson
2015-03-07 23:24 ` [PATCH v2 05/10] zip: use GIT_SHA1_HEXSZ for trailers brian m. carlson
2015-03-07 23:24 ` [PATCH v2 06/10] bulk-checkin.c: convert to use struct object_id brian m. carlson
2015-03-07 23:24 ` [PATCH v2 07/10] diff: convert struct combine_diff_path to object_id brian m. carlson
2015-03-07 23:24 ` [PATCH v2 08/10] commit: convert parts to struct object_id brian m. carlson
2015-03-11 14:46   ` Michael Haggerty
2015-03-07 23:24 ` [PATCH v2 09/10] patch-id: convert to use " brian m. carlson
2015-03-07 23:24 ` [PATCH v2 10/10] apply: convert threeway_stage to object_id brian m. carlson
2015-03-08  7:43 ` [PATCH v2 00/10] Use a structure for object IDs Junio C Hamano
2015-03-11  2:38 ` Kyle J. McKay
2015-03-11 16:08 ` Michael Haggerty
2015-03-11 20:35   ` Junio C Hamano
2015-03-13 22:45     ` brian m. carlson
  -- strict thread matches above, loose matches on Subject: below --
2015-03-13 23:39 brian m. carlson
2015-03-13 23:39 ` [PATCH v2 01/10] Define " brian m. carlson

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