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From: Derrick Stolee <stolee@gmail.com>
To: Elijah Newren <newren@gmail.com>,
	Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Cc: Git Mailing List <git@vger.kernel.org>,
	Derrick Stolee <derrickstolee@github.com>,
	Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH 1/9] cache-tree: clean up cache_tree_update()
Date: Wed, 20 Jan 2021 14:10:30 -0500	[thread overview]
Message-ID: <bbed0d73-fa9d-92a0-3bc4-1d44263bb2fb@gmail.com> (raw)
In-Reply-To: <CABPp-BFiNvPaAffQ0uBfpkHY1WM2gR3ssvpwzxpDhrZmZZjiDA@mail.gmail.com>

On 1/20/2021 12:21 PM, Elijah Newren wrote:
> On Wed, Jan 20, 2021 at 8:54 AM Derrick Stolee via GitGitGadget
> <gitgitgadget@gmail.com> wrote:...
>> +
>> +       if (!istate->cache_tree)
>> +               istate->cache_tree = cache_tree();
> 
> This is the only substantive change.  It seems fairly innocuous, but
> it makes me wonder the reasoning...I don't know/remember enough about
> cache_tree handling to know when this would or wouldn't have already
> been allocated.  It seems that this would have had to segfault below
> if istate->cache_tree were ever NULL, and I don't see you mentioning
> any bug you are fixing, so I presume this means you are going to be
> adding new codepaths somewhere that cause this function to be reached
> under different circumstances than previously had been and you need it
> to be more safe for those.  Is that correct?  Or is it just an
> abundance of caution thing that you're adding?  If the latter, any
> reason you chose to allocate one rather than assume it's a violation
> of design invariants and BUG() instead?  (Perhaps the commit message
> could add a sentence about the rationale for the extra safety?)

It's something I need in the future when I use the cache_tree_update()
in more places. I think I call it two times, and either I need to
initialize the cache_tree member outside of both, or just make it a
feature of the method that it will re-initialize the cache-tree.

Note: the implementation treats an initialized, but empty cache-tree
as "invalid" so update_one() correctly populates the full tree.

Thanks,
-Stolee


  reply	other threads:[~2021-01-20 19:11 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-20 16:53 [PATCH 0/9] More index cleanups Derrick Stolee via GitGitGadget
2021-01-20 16:53 ` [PATCH 1/9] cache-tree: clean up cache_tree_update() Derrick Stolee via GitGitGadget
2021-01-20 17:21   ` Elijah Newren
2021-01-20 19:10     ` Derrick Stolee [this message]
2021-01-20 16:53 ` [PATCH 2/9] cache-tree: extract subtree_pos() Derrick Stolee via GitGitGadget
2021-01-20 17:23   ` Elijah Newren
2021-01-20 16:53 ` [PATCH 3/9] fsmonitor: de-duplicate BUG()s around dirty bits Derrick Stolee via GitGitGadget
2021-01-20 17:26   ` Elijah Newren
2021-01-21 12:53   ` Chris Torek
2021-01-21 15:56     ` Derrick Stolee
2021-01-20 16:53 ` [PATCH 4/9] repository: add repo reference to index_state Derrick Stolee via GitGitGadget
2021-01-20 17:46   ` Elijah Newren
2021-01-20 19:16     ` Derrick Stolee
2021-01-20 19:50       ` Elijah Newren
2021-01-20 16:53 ` [PATCH 5/9] name-hash: use trace2 regions for init Derrick Stolee via GitGitGadget
2021-01-20 17:47   ` Elijah Newren
2021-01-20 16:53 ` [PATCH 6/9] sparse-checkout: load sparse-checkout patterns Derrick Stolee via GitGitGadget
2021-01-20 17:54   ` Elijah Newren
2021-01-20 16:53 ` [PATCH 7/9] sparse-checkout: hold pattern list in index Derrick Stolee via GitGitGadget
2021-01-20 18:03   ` Elijah Newren
2021-01-20 19:22     ` Derrick Stolee
2021-01-20 16:53 ` [PATCH 8/9] test-lib: test_region looks for trace2 regions Derrick Stolee via GitGitGadget
2021-01-20 18:20   ` Elijah Newren
2021-01-20 19:24     ` Derrick Stolee
2021-01-20 16:53 ` [PATCH 9/9] t1092: test interesting sparse-checkout scenarios Derrick Stolee via GitGitGadget
2021-01-20 19:40   ` Elijah Newren
2021-01-21 11:59     ` Derrick Stolee
2021-01-22 13:03 ` [PATCH v2 0/8] More index cleanups Derrick Stolee via GitGitGadget
2021-01-22 13:03   ` [PATCH v2 1/8] cache-tree: clean up cache_tree_update() Derrick Stolee via GitGitGadget
2021-01-22 19:11     ` Junio C Hamano
2021-01-22 13:03   ` [PATCH v2 2/8] cache-tree: extract subtree_pos() Derrick Stolee via GitGitGadget
2021-01-22 13:03   ` [PATCH v2 3/8] fsmonitor: de-duplicate BUG()s around dirty bits Derrick Stolee via GitGitGadget
2021-01-22 19:18     ` Junio C Hamano
2021-01-22 13:03   ` [PATCH v2 4/8] repository: add repo reference to index_state Derrick Stolee via GitGitGadget
2021-01-22 19:23     ` Junio C Hamano
2021-01-22 13:03   ` [PATCH v2 5/8] name-hash: use trace2 regions for init Derrick Stolee via GitGitGadget
2021-01-22 13:03   ` [PATCH v2 6/8] sparse-checkout: load sparse-checkout patterns Derrick Stolee via GitGitGadget
2021-01-22 13:03   ` [PATCH v2 7/8] test-lib: test_region looks for trace2 regions Derrick Stolee via GitGitGadget
2021-01-22 19:42     ` Junio C Hamano
2021-01-23 18:36       ` Derrick Stolee
2021-01-23 18:50         ` Junio C Hamano
2021-01-22 13:03   ` [PATCH v2 8/8] t1092: test interesting sparse-checkout scenarios Derrick Stolee via GitGitGadget
2021-01-22 19:49   ` [PATCH v2 0/8] More index cleanups Elijah Newren
2021-01-23 18:47     ` Derrick Stolee
2021-01-23 19:58   ` [PATCH v3 0/9] " Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 1/9] cache-tree: clean up cache_tree_update() Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 2/9] cache-tree: simplify verify_cache() prototype Derrick Stolee via GitGitGadget
2021-01-23 20:24       ` Elijah Newren
2021-01-23 21:02         ` Derrick Stolee
2021-01-23 21:10           ` Elijah Newren
2021-01-23 21:41           ` Junio C Hamano
2021-01-23 21:10         ` Junio C Hamano
2021-01-23 21:14           ` Derrick Stolee
2021-01-23 19:58     ` [PATCH v3 3/9] cache-tree: extract subtree_pos() Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 4/9] fsmonitor: de-duplicate BUG()s around dirty bits Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 5/9] repository: add repo reference to index_state Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 6/9] name-hash: use trace2 regions for init Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 7/9] sparse-checkout: load sparse-checkout patterns Derrick Stolee via GitGitGadget
2021-01-23 19:58     ` [PATCH v3 8/9] test-lib: test_region looks for trace2 regions Derrick Stolee via GitGitGadget
2021-01-23 21:07       ` Derrick Stolee
2021-01-23 19:58     ` [PATCH v3 9/9] t1092: test interesting sparse-checkout scenarios Derrick Stolee via GitGitGadget
2021-01-25 18:45       ` Elijah Newren
2021-01-23 20:29     ` [PATCH v3 0/9] More index cleanups Elijah Newren
2021-01-23 21:05       ` Derrick Stolee
2021-01-23 21:42         ` Junio C Hamano

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