# Split commit graphs and commit-graph read 5 messages from 2019-11-08 to 2019-11-12. Participants: Bryan Turner, Derrick Stolee, Junio C Hamano, Jeff King. Thread: https://gitlist.dev/t/52224 ## Bryan Turner, 2019-11-08 23:41 Subject: Split commit graphs and commit-graph read Message-ID: URL: https://gitlist.dev/e/CAGyf7-G3NDp--2nUbri_0EqvSLF21M0gsFCOKDCWMY%2Be68Htog%40mail.gmail.com ``` Just a quick question about a behavior I've noticed with the commit graph. (Amazing feature, by the way!) If the _very first_ write done is split: git commit-graph write --reachable --split You end up with something like this: .../objects$ ls -R info info: commit-graphs packs info/commit-graphs: commit-graph-chain graph-6612fcc8fd04d3af2cc268a6bd9161ae40f5fcbf.graph info/commit-graph doesn't exist, but I have a 1-graph "chain" in place. (And subsequent write --split calls write additional ones; I've got a few now in this repository, but still no info/commit-graph.) git commit-graph verify seems happy: .../objects$ git commit-graph verify Verifying commits in commit graph: 100% (98768/98768), done. But git commit-graph read isn't: .../objects$ git commit-graph read fatal: Could not open commit-graph '/path/to/repository/objects/info/commit-graph': No such file or directory Running some tests with commands like git for-each-ref and git rev-list shows that the "split" commit graph is being used (setting core.commitGraph=false makes commands noticeably slower), so functionally all seems well. But should git commit-graph read be handling this better? Best regards, Bryan Turner ``` ## Derrick Stolee, 2019-11-11 01:19 Subject: Re: Split commit graphs and commit-graph read Message-ID: <87f16645-6af4-9703-1d0d-eb64728d2849@gmail.com> URL: https://gitlist.dev/e/87f16645-6af4-9703-1d0d-eb64728d2849%40gmail.com In-Reply-To: ``` On 11/8/2019 6:41 PM, Bryan Turner wrote: Hi Bryan, > Just a quick question about a behavior I've noticed with the commit > graph. (Amazing feature, by the way!) > If the _very first_ write done is split: > git commit-graph write --reachable --split > > You end up with something like this: > .../objects$ ls -R info > info: > commit-graphs packs > > info/commit-graphs: > commit-graph-chain graph-6612fcc8fd04d3af2cc268a6bd9161ae40f5fcbf.graph > > info/commit-graph doesn't exist, but I have a 1-graph "chain" in > place. (And subsequent write --split calls write additional ones; I've > got a few now in this repository, but still no info/commit-graph.) > > git commit-graph verify seems happy: > .../objects$ git commit-graph verify > Verifying commits in commit graph: 100% (98768/98768), done. This workflow seems expected. > But git commit-graph read isn't: > .../objects$ git commit-graph read > fatal: Could not open commit-graph > '/path/to/repository/objects/info/commit-graph': No such file or > directory > > Running some tests with commands like git for-each-ref and git > rev-list shows that the "split" commit graph is being used (setting > core.commitGraph=false makes commands noticeably slower), so > functionally all seems well. But should git commit-graph read be > handling this better? Unfortunately, you're running into an issue because I designed the "read" subcommand poorly (and also forgot to update it for incremental commit-graph files). The biggest issue is that "read" is not really meant for end-users. It really should have been built as a test-tool. This point was corrected when I got around to writing the multi-pack-index since it uses "test-tool read-midx" instead of add. To fix this issue, I would probably go about it by removing the "read" subcommand and creating a "test-tool read-commit-graph" for the tests that need that output. If others on-list think that the better thing to do is to update the "read" subcommand to provide the same output, but iterate over each layer of an incremental commit-graph, then I can do that work instead. Thanks, -Stolee ``` ## Junio C Hamano, 2019-11-11 02:09 Subject: Re: Split commit graphs and commit-graph read Message-ID: URL: https://gitlist.dev/e/xmqq1rufjh9n.fsf%40gitster-ct.c.googlers.com In-Reply-To: <87f16645-6af4-9703-1d0d-eb64728d2849@gmail.com> ``` Derrick Stolee writes: > To fix this issue, I would probably go about it by removing the "read" > subcommand and creating a "test-tool read-commit-graph" for the tests > that need that output. > > If others on-list think that the better thing to do is to update the > "read" subcommand to provide the same output, but iterate over each > layer of an incremental commit-graph, then I can do that work instead. I think moving it to test-tool is a good idea, whether the output presents a single result that consolidates all layers together, or allows to name just a single layer and shows its contents. I do not have a strong opinion between the two (both sounds usable debugging aid). Thanks. ``` ## Jeff King, 2019-11-11 03:29 Subject: Re: Split commit graphs and commit-graph read Message-ID: <20191111032946.GA5912@sigill.intra.peff.net> URL: https://gitlist.dev/e/20191111032946.GA5912%40sigill.intra.peff.net In-Reply-To: <87f16645-6af4-9703-1d0d-eb64728d2849@gmail.com> ``` On Sun, Nov 10, 2019 at 08:19:20PM -0500, Derrick Stolee wrote: > > Running some tests with commands like git for-each-ref and git > > rev-list shows that the "split" commit graph is being used (setting > > core.commitGraph=false makes commands noticeably slower), so > > functionally all seems well. But should git commit-graph read be > > handling this better? > > Unfortunately, you're running into an issue because I designed the > "read" subcommand poorly (and also forgot to update it for > incremental commit-graph files). The biggest issue is that "read" > is not really meant for end-users. It really should have been built > as a test-tool. This point was corrected when I got around to writing > the multi-pack-index since it uses "test-tool read-midx" instead of > add. > > To fix this issue, I would probably go about it by removing the "read" > subcommand and creating a "test-tool read-commit-graph" for the tests > that need that output. > > If others on-list think that the better thing to do is to update the > "read" subcommand to provide the same output, but iterate over each > layer of an incremental commit-graph, then I can do that work instead. In theory I suppose one could use it to debug a commit-graph file "in the field" as it were, where somebody does not necessarily have the test-tool programs. But in practice, I have not ever done that (I didn't even know "commit-graph read" was there), and it's not that big a deal to just have a build of git.git handy. I'd be much more likely to use "commit-graph verify". And perhaps it could grow a "--verbose" flag if somebody really wants that (but I think it would be fine to punt until somebody cares enough to do so). I guess dropping the sub-command is technically a backwards incompatible change, but since it didn't do anything that normal users would find useful in the first place, I wouldn't be sorry to see it go. -Peff ``` ## Bryan Turner, 2019-11-12 00:28 Subject: Re: Split commit graphs and commit-graph read Message-ID: URL: https://gitlist.dev/e/CAGyf7-EqQdvg4fQcZJv6BpqZ9hPDx72KBiLp1Xe3Ur7NrSMBeA%40mail.gmail.com In-Reply-To: <87f16645-6af4-9703-1d0d-eb64728d2849@gmail.com> ``` On Sun, Nov 10, 2019 at 5:19 PM Derrick Stolee wrote: > > > But git commit-graph read isn't: > > .../objects$ git commit-graph read > > fatal: Could not open commit-graph > > '/path/to/repository/objects/info/commit-graph': No such file or > > directory > > > > Running some tests with commands like git for-each-ref and git > > rev-list shows that the "split" commit graph is being used (setting > > core.commitGraph=false makes commands noticeably slower), so > > functionally all seems well. But should git commit-graph read be > > handling this better? > > Unfortunately, you're running into an issue because I designed the > "read" subcommand poorly (and also forgot to update it for > incremental commit-graph files). The biggest issue is that "read" > is not really meant for end-users. It really should have been built > as a test-tool. This point was corrected when I got around to writing > the multi-pack-index since it uses "test-tool read-midx" instead of > add. > > To fix this issue, I would probably go about it by removing the "read" > subcommand and creating a "test-tool read-commit-graph" for the tests > that need that output. > > If others on-list think that the better thing to do is to update the > "read" subcommand to provide the same output, but iterate over each > layer of an incremental commit-graph, then I can do that work instead. I was only running "git commit-graph read" as another way of verifying that everything looked good (to Git, that is). I'd already run "git commit-graph verify" and just found the discrepancy in their behavior surprising/interesting. For what it's worth, I personally don't see anything amiss with removing the "read" subcommand if that's simpler than updating it to handle incremental graphs. (Put differently, it's not a command I'd ever have Bitbucket Server run, or that I'm likely to try and run going forward. In this case I just completed some commit graph-related changes to Bitbucket Server and was looking for every possible avenue I could pursue to try and ensure what I did was producing the "correct" output after my changes got deployed to our internal dogfooding server.) Thanks for taking the time to look into it and clarify the behavior! I really appreciate it. Best regards, Bryan Turner > > Thanks, > -Stolee ```