From: Derrick Stolee <stolee@gmail.com>
To: "René Scharfe" <l.s.r@web.de>,
"SZEDER Gábor via GitGitGadget" <gitgitgadget@gmail.com>,
git@vger.kernel.org
Cc: me@ttaylorr.com, szeder.dev@gmail.com,
Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH v2 07/11] commit-graph: check chunk sizes after writing
Date: Thu, 25 Jun 2020 11:02:49 -0400 [thread overview]
Message-ID: <5cb45264-1788-a563-a0e1-40ec7e64644a@gmail.com> (raw)
In-Reply-To: <de5453ed-6db9-ebd5-28f9-8db4f9ed8447@web.de>
On 6/25/2020 3:25 AM, René Scharfe wrote:
> Am 23.06.20 um 19:47 schrieb SZEDER Gábor via GitGitGadget:
>> From: =?UTF-8?q?SZEDER=20G=C3=A1bor?= <szeder.dev@gmail.com>
>>
>> In my experience while experimenting with new commit-graph chunks,
>> early versions of the corresponding new write_commit_graph_my_chunk()
>> functions are, sadly but not surprisingly, often buggy, and write more
>> or less data than they are supposed to, especially if the chunk size
>> is not directly proportional to the number of commits. This then
>> causes all kinds of issues when reading such a bogus commit-graph
>> file, raising the question of whether the writing or the reading part
>> happens to be buggy this time.
>>
>> Let's catch such issues early, already when writing the commit-graph
>> file, and check that each write_graph_chunk_*() function wrote the
>> amount of data that it was expected to, and what has been encoded in
>> the Chunk Lookup table. Now that all commit-graph chunks are written
>> in a loop we can do this check in a single place for all chunks, and
>> any chunks added in the future will get checked as well.
>>
>> Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
>> Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
>> ---
>> commit-graph.c | 9 +++++++++
>> 1 file changed, 9 insertions(+)
>>
>> diff --git a/commit-graph.c b/commit-graph.c
>> index 086fc2d070..1de6800d74 100644
>> --- a/commit-graph.c
>> +++ b/commit-graph.c
>> @@ -1683,12 +1683,21 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
>> num_chunks * ctx->commits.nr);
>> }
>>
>> + chunk_offset = f->total + f->offset;
>> for (i = 0; i < num_chunks; i++) {
>> + uint64_t end_offset;
>> +
>
> Hmm, the added code looks complicated because it keeps state outside the
> loop, but it could be replace by this:
>
> uint64_t start_offset = f->total + f->offset;
>
>> if (chunks[i].write_fn(f, ctx)) {
>> error(_("failed writing chunk with id %"PRIx32""),
>> chunks[i].id);
>> return -1;
>> }
>> +
>> + end_offset = f->total + f->offset;
>> + if (end_offset - chunk_offset != chunks[i].size)
>> + BUG("expected to write %"PRId64" bytes to chunk %"PRIx32", but wrote %"PRId64" instead",
>> + chunks[i].size, chunks[i].id, end_offset - chunk_offset);
>> + chunk_offset = end_offset;
>
> ... and that:
>
> if (f->total + f->offset != start_offset + chunks[i].size)
> BUG(...);
Thanks! I agree this approach is simpler and less prone to
bugs since we are using the local state.
-Stolee
next prev parent reply other threads:[~2020-06-25 15:02 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-15 20:14 [PATCH 0/8] More commit-graph/Bloom filter improvements Derrick Stolee via GitGitGadget
2020-06-15 20:14 ` [PATCH 1/8] commit-graph: place bloom_settings in context Derrick Stolee via GitGitGadget
2020-06-18 20:30 ` René Scharfe
2020-06-19 12:58 ` Derrick Stolee
2020-06-15 20:14 ` [PATCH 2/8] commit-graph: unify the signatures of all write_graph_chunk_*() functions SZEDER Gábor via GitGitGadget
2020-06-18 20:30 ` René Scharfe
2020-06-15 20:14 ` [PATCH 3/8] commit-graph: simplify chunk writes into loop SZEDER Gábor via GitGitGadget
2020-06-18 20:30 ` René Scharfe
2020-06-15 20:14 ` [PATCH 4/8] commit-graph: check chunk sizes after writing SZEDER Gábor via GitGitGadget
2020-06-15 20:14 ` [PATCH 5/8] commit-graph: check all leading directories in changed path Bloom filters SZEDER Gábor via GitGitGadget
2020-06-18 20:31 ` René Scharfe
2020-06-19 9:14 ` René Scharfe
2020-06-19 17:17 ` Taylor Blau
2020-06-19 17:19 ` Taylor Blau
2020-06-23 13:47 ` Derrick Stolee
2020-06-15 20:14 ` [PATCH 6/8] bloom: enforce a minimum size of 8 bytes Derrick Stolee via GitGitGadget
2020-06-15 20:14 ` [PATCH 7/8] commit-graph: change test to die on parse, not load Derrick Stolee via GitGitGadget
2020-06-15 20:14 ` [PATCH 8/8] commit-graph: persist existence of changed-paths Derrick Stolee via GitGitGadget
2020-06-17 21:21 ` [PATCH 0/8] More commit-graph/Bloom filter improvements Junio C Hamano
2020-06-18 1:46 ` Derrick Stolee
2020-06-23 17:46 ` [PATCH v2 00/11] " Derrick Stolee via GitGitGadget
2020-06-23 17:47 ` [PATCH v2 01/11] commit-graph: place bloom_settings in context Derrick Stolee via GitGitGadget
2020-06-23 17:47 ` [PATCH v2 02/11] commit-graph: change test to die on parse, not load Derrick Stolee via GitGitGadget
2020-06-23 17:47 ` [PATCH v2 03/11] bloom: get_bloom_filter() cleanups Derrick Stolee via GitGitGadget
2020-06-25 7:24 ` René Scharfe
2020-06-23 17:47 ` [PATCH v2 04/11] commit-graph: persist existence of changed-paths Derrick Stolee via GitGitGadget
2020-06-23 17:47 ` [PATCH v2 05/11] commit-graph: unify the signatures of all write_graph_chunk_*() functions SZEDER Gábor via GitGitGadget
2020-06-25 7:25 ` René Scharfe
2020-06-23 17:47 ` [PATCH v2 06/11] commit-graph: simplify chunk writes into loop SZEDER Gábor via GitGitGadget
2020-06-25 7:25 ` René Scharfe
2020-06-25 14:59 ` Derrick Stolee
2020-06-23 17:47 ` [PATCH v2 07/11] commit-graph: check chunk sizes after writing SZEDER Gábor via GitGitGadget
2020-06-25 7:25 ` René Scharfe
2020-06-25 15:02 ` Derrick Stolee [this message]
2020-06-23 17:47 ` [PATCH v2 08/11] revision.c: fix whitespace Derrick Stolee via GitGitGadget
2020-06-23 17:47 ` [PATCH v2 09/11] revision: empty pathspecs should not use Bloom filters Taylor Blau via GitGitGadget
2020-06-23 17:47 ` [PATCH v2 10/11] commit-graph: check all leading directories in changed path " SZEDER Gábor via GitGitGadget
2020-06-25 7:25 ` René Scharfe
2020-06-25 15:05 ` Derrick Stolee
2020-06-26 6:34 ` SZEDER Gábor
2020-06-26 14:42 ` Derrick Stolee
2020-06-23 17:47 ` [PATCH v2 11/11] bloom: enforce a minimum size of 8 bytes Derrick Stolee via GitGitGadget
2020-06-24 23:11 ` [PATCH v2 00/11] More commit-graph/Bloom filter improvements Junio C Hamano
2020-06-24 23:32 ` Derrick Stolee
2020-06-25 0:38 ` Junio C Hamano
2020-06-25 13:38 ` Derrick Stolee
2020-06-25 16:34 ` Junio C Hamano
2020-06-26 12:30 ` [PATCH v3 00/10] " Derrick Stolee via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 01/10] commit-graph: place bloom_settings in context Derrick Stolee via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 02/10] commit-graph: change test to die on parse, not load Derrick Stolee via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 03/10] bloom: fix logic in get_bloom_filter() Derrick Stolee via GitGitGadget
2020-06-27 16:33 ` SZEDER Gábor
2020-06-29 13:02 ` Derrick Stolee
2020-06-26 12:30 ` [PATCH v3 04/10] commit-graph: persist existence of changed-paths Derrick Stolee via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 05/10] commit-graph: unify the signatures of all write_graph_chunk_*() functions SZEDER Gábor via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 06/10] commit-graph: simplify chunk writes into loop SZEDER Gábor via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 07/10] commit-graph: check chunk sizes after writing SZEDER Gábor via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 08/10] revision.c: fix whitespace Derrick Stolee via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 09/10] revision: empty pathspecs should not use Bloom filters Taylor Blau via GitGitGadget
2020-06-26 12:30 ` [PATCH v3 10/10] commit-graph: check all leading directories in changed path " SZEDER Gábor via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 00/10] More commit-graph/Bloom filter improvements Derrick Stolee via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 01/10] commit-graph: place bloom_settings in context Derrick Stolee via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 02/10] commit-graph: change test to die on parse, not load Derrick Stolee via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 03/10] bloom: fix logic in get_bloom_filter() Derrick Stolee via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 04/10] commit-graph: persist existence of changed-paths Derrick Stolee via GitGitGadget
2020-10-15 13:21 ` SZEDER Gábor
2020-10-15 21:41 ` Taylor Blau
2020-10-16 2:18 ` Derrick Stolee
2020-10-16 3:18 ` Taylor Blau
2020-10-16 13:52 ` Derrick Stolee
2020-07-01 13:27 ` [PATCH v4 05/10] commit-graph: unify the signatures of all write_graph_chunk_*() functions SZEDER Gábor via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 06/10] commit-graph: simplify chunk writes into loop SZEDER Gábor via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 07/10] commit-graph: check chunk sizes after writing SZEDER Gábor via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 08/10] revision.c: fix whitespace Derrick Stolee via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 09/10] revision: empty pathspecs should not use Bloom filters Taylor Blau via GitGitGadget
2020-07-01 13:27 ` [PATCH v4 10/10] commit-graph: check all leading directories in changed path " SZEDER Gábor via GitGitGadget
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