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From: Thomas Gummerer <t.gummerer@gmail.com>
To: Duy Nguyen <pclouds@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	Thomas Rast <trast@inf.ethz.ch>,
	Michael Haggerty <mhagger@alum.mit.edu>,
	Junio C Hamano <gitster@pobox.com>,
	Robin Rosenberg <robin.rosenberg@dewire.com>,
	Eric Sunshine <sunshine@sunshineco.com>
Subject: Re: [PATCH v2 07/19] make sure partially read index is not changed
Date: Wed, 17 Jul 2013 14:56:52 +0200	[thread overview]
Message-ID: <87li55s5t7.fsf@gmail.com> (raw)
In-Reply-To: <CACsJy8A61gfWsMecJha-3GoWXFT0bb3zAMJ5YT-a=vs=_3WghQ@mail.gmail.com>

Duy Nguyen <pclouds@gmail.com> writes:

> On Sat, Jul 13, 2013 at 12:26 AM, Thomas Gummerer <t.gummerer@gmail.com> wrote:
>> A partially read index file currently cannot be written to disk.  Make
>> sure that never happens, by erroring out when a caller tries to change a
>> partially read index.  The caller is responsible for reading the whole
>> index when it's trying to change it later.
>>
>> Forcing the caller to load the right part of the index file instead of
>> re-reading it when changing it, gives a bit of a performance advantage,
>> by avoiding to read parts of the index twice.
>
> If you want to be strict about this, put similar check in
> fill_stat_cache_info (used by entry.c), cache_tree_invalidate_path and
> convert the code base (maybe except unpack-trees.c, just put a check
> in the beginning of unpack_trees()) to use wrapper function to change
> ce_flags (some still update ce_flags directly, grep them). Some flags
> are in memory only and should be allowed to change in partial index,
> some are to be written on disk and should not be allowed.

I'm not sure anymore we should even be this strict.  A partially read
index will never make it to the disk, because write_index checks if it's
fully read.   I think the check in write_index and read_index_filtered
would be enough.

The only disadvantage would be that it takes a little longer to catch an
error that should never happen in the first place.  If it occurs the
user has bigger problems than the time that not having caught the
error earlier adds to the execution of the command.

I also don't see a clean way to add the check to fill_stat_cache_info or
cache_tree_invalidate_path, because we would need an additional
parameter for the index_state, or at least for index_state->filter_opts,
which doesn't do anything but check if the index is only partially loaded.

  reply	other threads:[~2013-07-17 12:57 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-07-12 17:26 [PATCH v2 00/19] Index-v5 Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 01/19] t2104: Don't fail for index versions other than [23] Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 02/19] read-cache: split index file version specific functionality Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 03/19] read-cache: move index v2 specific functions to their own file Thomas Gummerer
2013-07-14  3:10   ` Duy Nguyen
2013-07-19 14:53     ` Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 04/19] read-cache: Re-read index if index file changed Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 05/19] Add documentation for the index api Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 06/19] read-cache: add index reading api Thomas Gummerer
2013-07-14  3:21   ` Duy Nguyen
2013-07-12 17:26 ` [PATCH v2 07/19] make sure partially read index is not changed Thomas Gummerer
2013-07-14  3:29   ` Duy Nguyen
2013-07-17 12:56     ` Thomas Gummerer [this message]
2013-07-12 17:26 ` [PATCH v2 08/19] grep.c: Use index api Thomas Gummerer
2013-07-14  3:32   ` Duy Nguyen
2013-07-15  9:51     ` Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 09/19] ls-files.c: use " Thomas Gummerer
2013-07-14  3:39   ` Duy Nguyen
2013-07-17  8:07     ` Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 10/19] documentation: add documentation of the index-v5 file format Thomas Gummerer
2013-07-14  3:59   ` Duy Nguyen
2013-07-17  8:09     ` Thomas Gummerer
2013-08-04 11:26   ` Duy Nguyen
2013-08-04 17:58     ` Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 11/19] read-cache: make in-memory format aware of stat_crc Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 12/19] read-cache: read index-v5 Thomas Gummerer
2013-07-14  4:42   ` Duy Nguyen
2013-08-07  8:13     ` Thomas Gummerer
2013-07-15 10:12   ` Duy Nguyen
2013-07-17  8:11     ` Thomas Gummerer
2013-08-08  2:00       ` Duy Nguyen
2013-08-08 13:28         ` Thomas Gummerer
2013-08-09 13:10         ` Thomas Gummerer
2013-08-07  8:23     ` Thomas Gummerer
2013-08-08  2:09       ` Duy Nguyen
2013-07-12 17:26 ` [PATCH v2 13/19] read-cache: read resolve-undo data Thomas Gummerer
2013-07-12 17:26 ` [PATCH v2 14/19] read-cache: read cache-tree in index-v5 Thomas Gummerer
2013-07-12 17:27 ` [PATCH v2 15/19] read-cache: write index-v5 Thomas Gummerer
2013-07-12 17:27 ` [PATCH v2 16/19] read-cache: write index-v5 cache-tree data Thomas Gummerer
2013-07-12 17:27 ` [PATCH v2 17/19] read-cache: write resolve-undo data for index-v5 Thomas Gummerer
2013-07-12 17:27 ` [PATCH v2 18/19] update-index.c: rewrite index when index-version is given Thomas Gummerer
2013-07-12 17:27 ` [PATCH v2 19/19] p0003-index.sh: add perf test for the index formats Thomas Gummerer
2013-07-14  2:59 ` [PATCH v2 00/19] Index-v5 Duy Nguyen
2013-07-15  9:30   ` Thomas Gummerer
2013-07-15  9:38     ` Duy Nguyen
2013-07-17  8:12       ` Thomas Gummerer
2013-07-17 23:58         ` Junio C Hamano
2013-07-19 17:37           ` Thomas Gummerer
2013-07-19 18:25             ` Junio C Hamano
2013-07-16 21:03 ` Ramsay Jones
2013-07-17  8:04   ` Thomas Gummerer

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