summaryrefslogtreecommitdiff
path: root/t/t3705-add-sparse-checkout.sh
AgeCommit message (Collapse)Author
2022-04-22tests: stop assuming --no-cone is the default mode for sparse-checkoutElijah Newren
Add an explicit --no-cone to several sparse-checkout invocations in preparation for changing the default to cone mode. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-01-14repo_read_index: clear SKIP_WORKTREE bit from files present in worktreeElijah Newren
The fix is short (~30 lines), but the description is not. Sorry. There is a set of problems caused by files in what I'll refer to as the "present-despite-SKIP_WORKTREE" state. This commit aims to not just fix these problems, but remove the entire class as a possibility -- for those using sparse checkouts. But first, we need to understand the problems this class presents. A quick outline: * Problems * User facing issues * Problem space complexity * Maintenance and code correctness challenges * SKIP_WORKTREE expectations in Git * Suggested solution * Pros/Cons of suggested solution * Notes on testcase modifications === User facing issues === There are various ways for users to get files to be present in the working copy despite having the SKIP_WORKTREE bit set for that file in the index. This may come from: * various git commands not really supporting the SKIP_WORKTREE bit[1,2] * users grabbing files from elsewhere and writing them to the worktree (perhaps even cached in their editor) * users attempting to "abort" a sparse-checkout operation with a not-so-early Ctrl+C (updating $GIT_DIR/info/sparse-checkout and the working tree is not atomic)[3]. Once users have present-despite-SKIP_WORKTREE files, any modifications users make to these files will be ignored, possibly to users' confusion. Further: * these files will degrade performance for the sparse-index case due to requiring the index to be expanded (see commit 55dfcf9591 ("sparse-checkout: clear tracked sparse dirs", 2021-09-08) for why we try to delete entire directories outside the sparse cone). * these files will not be updated by by standard commands (switch/checkout/pull/merge/rebase will leave them alone unless conflicts happen -- and even then, the conflicted file may be written somewhere else to avoid overwriting the SKIP_WORKTREE file that is present and in the way) * there is nothing in Git that users can use to discover such files (status, diff, grep, etc. all ignore it) * there is no reasonable mechanism to "recover" from such a condition (neither `git sparse-checkout reapply` nor `git reset --hard` will correct it). So, not only are users modifications ignored, but the files get progressively more stale over time. At some point in the future, they may change their sparseness specification or disable sparse-checkouts. At that time, all present-despite-SKIP_WORKTREE files will show up as having lots of modifications because they represent a version from a different branch or commit. These might include user-made local changes from days before, but the only way to tell is to have users look through them all closely. If these users come to others for help, there will be no logs that explain the issue; it's just a mysterious list of changes. Users might adamantly claim (correctly, as it turns out) that they didn't modify these files, while others presume they did. [1] https://lore.kernel.org/git/xmqqbmb1a7ga.fsf@gitster-ct.c.googlers.com/ [2] https://lore.kernel.org/git/CABPp-BH9tju7WVm=QZDOvaMDdZbpNXrVWQdN-jmfN8wC6YVhmw@mail.gmail.com/ [3] https://lore.kernel.org/git/CABPp-BFnFpzwGC11TLoLs8YK5yiisA5D5-fFjXnJsbESVDwZsA@mail.gmail.com/ === Problem space complexity === SKIP_WORKTREE has been part of Git for over a decade. Duy did lots of work on it initially, and several others have since come along and put lots of work into it. Stolee spent most of 2021 on the sparse-index, with lots of bugfixes along the way including to non-sparse-index cases as we are still trying to get sparse checkouts to behave reasonably. Basically every codepath throughout the treat needs to be aware of an additional type of file: tracked-but-not-present. The extra type results in lots of extra testcases and lots of extra code everywhere. But, the sad thing is that we actually have more than one extra type. We have tracked, tracked-but-not-present (SKIP_WORKTREE), and tracked-but-promised-to-not-be-present-but-is-present-anyway (present-despite-SKIP_WORKTREE). Two types is a monumental amount of effort to support, and adding a third feels a bit like insanity[4]. [4] Some examples of which can be seen at https://lore.kernel.org/git/CABPp-BGJ_Nvi5TmgriD9Bh6eNXE2EDq2f8e8QKXAeYG3BxZafA@mail.gmail.com/ === Maintenance and code correctness challenges === Matheus' patches to grep stalled for nearly a year, in part because of complications of how to handle sparse-checkouts appropriately in all cases[5][6] (with trying to sanely figure out how to sanely handle present-despite-SKIP_WORKTREE files being one of the complications). His rm/add follow-ups also took months because of those kinds of issues[7]. The corner cases with things like submodules and SKIP_WORKTREE with the addition of present-despite-SKIP_WORKTREE start becoming really complex[8]. We've had to add ugly logic to merge-ort to attempt to handle present-despite-SKIP_WORKTREE files[9], and basically just been forced to give up in merge-recursive knowing full well that we'll sometimes silently discard user modifications. Despite stash essentially being a merge, it needed extra code (beyond what was in merge-ort and merge-recursive) to manually tweak SKIP_WORKTREE bits in order to avoid a few different bugs that'd result in an early abort with a partial stash application[10]. [5] See https://lore.kernel.org/git/5f3f7ac77039d41d1692ceae4b0c5df3bb45b74a.1612901326.git.matheus.bernardino@usp.br/#t and the dates on the thread; also Matheus and I had several conversations off-list trying to resolve the issues over that time [6] ...it finally kind of got unstuck after https://lore.kernel.org/git/CABPp-BGJ_Nvi5TmgriD9Bh6eNXE2EDq2f8e8QKXAeYG3BxZafA@mail.gmail.com/ [7] See for example https://lore.kernel.org/git/CABPp-BHwNoVnooqDFPAsZxBT9aR5Dwk5D9sDRCvYSb8akxAJgA@mail.gmail.com/#t and quotes like "The core functionality of sparse-checkout has always been only partially implemented", a statement I still believe is true today. [8] https://lore.kernel.org/git/pull.809.git.git.1592356884310.gitgitgadget@gmail.com/ [9] See commit 66b209b86a ("merge-ort: implement CE_SKIP_WORKTREE handling with conflicted entries", 2021-03-20) [10] See commit ba359fd507 ("stash: fix stash application in sparse-checkouts", 2020-12-01) === SKIP_WORKTREE expectations in Git === A couple quotes: * From [11] (before the "sparse-checkout" command existed): If it needs too many special cases, hacks, and conditionals, then it is not worth the complexity---if it is easier to write a correct code by allowing Git to populate working tree files, it is perfectly fine to do so. In a sense, the sparse checkout "feature" itself is a hack by itself, and that is why I think this part should be "best effort" as well. * From the git-sparse-checkout manual (still present today): THIS COMMAND IS EXPERIMENTAL. ITS BEHAVIOR, AND THE BEHAVIOR OF OTHER COMMANDS IN THE PRESENCE OF SPARSE-CHECKOUTS, WILL LIKELY CHANGE IN THE FUTURE. [11] https://lore.kernel.org/git/xmqqbmb1a7ga.fsf@gitster-ct.c.googlers.com/ === Suggested solution === SKIP_WORKTREE was written to allow sparse-checkouts, in particular, as the name of the option implies, to allow the file to NOT be in the worktree but consider it to be unchanged rather than deleted. The suggests a simple solution: present-despite-SKIP_WORKTREE files should not exist, for those using sparse-checkouts. Enforce this at index loading time by checking if core.sparseCheckout is true; if so, check files in the index with the SKIP_WORKTREE bit set to verify that they are absent from the working tree. If they are present, unset the bit (in memory, though any commands that write to the index will record the update). Users can, of course, can get the SKIP_WORKTREE bit back such as by running `git sparse-checkout reapply` (if they have ensured the file is unmodified and doesn't match the specified sparsity patterns). === Pros/Cons of suggested solution === Pros: * Solves the user visible problems reported above, which I've been complaining about for nearly a year but couldn't find a solution to. * Helps prevent slow performance degradation with a sparse-index. * Much easier behavior in sparse-checkouts for users to reason about * Very simple, ~30 lines of code. * Significantly simplifies some ugly testcases, and obviates the need to test an entire class of potential issues. * Reduces code complexity, reasoning, and maintenance. Avoids disagreements about weird corner cases[12]. * It has been reported that some users might be (ab)using SKIP_WORKTREE as a let-me-modify-but-keep-the-file-in-the-worktree mechanism[13, and a few other similar references]. These users know of multiple caveats and shortcomings in doing so; perhaps not surprising given the "SKIP_WORKTREE expecations" section above. However, these users use `git update-index --skip-worktree`, and not `git sparse-checkout` or core.sparseCheckout=true. As such, these users would be unaffected by this change and can continue abusing the system as before. [12] https://lore.kernel.org/git/CABPp-BH9tju7WVm=QZDOvaMDdZbpNXrVWQdN-jmfN8wC6YVhmw@mail.gmail.com/ [13] https://stackoverflow.com/questions/13630849/git-difference-between-assume-unchanged-and-skip-worktree Cons: * When core.sparseCheckout is enabled, this adds a performance cost to reading the index. I'll defer discussion of this cost to a subsequent patch, since I have some optimizations to add. === Notes on testcase modifications === The good: * t1011: Compare to two cases above it ('read-tree will not throw away dirty changes, non-sparse'); since the file is present, it should match the non-sparse case now * t1092: sparse-index & sparse-checkout now match full-worktree behavior in more cases! Yaay for consistency! * t6428, t7012: look at how much simpler the tests become! Merge and stash can just fail early telling the user there's a file in the way, instead of not noticing until it's about to write a file and then have to implement sudden crash avoidance. Hurray for sanity! * t7817: sparse behavior better matches full tree behavior. Hurray for sanity! The confusing: * t3705: These changes were ONLY needed on Windows, but they don't hurt other platforms. Let's discuss each individually: * core.sparseCheckout should be false by default. Nothing in this testcase toggles that until many, many tests later. However, early tests (#5 in particular) were testing `update-index --skip-worktree` behavior in a non-sparse-checkout, but the Windows tests in CI were behaving as if core.sparseCheckout=true had been specified somewhere. I do not have access to a Windows machine. But I just manually did what should have been a no-op and turned the config off. And it fixed the test. * I have no idea why the leftover .gitattributes file from this test was causing failures for test #18 on Windows, but only with these changes of mine. Test #18 was checking for empty stderr, and specifically wanted to know that some error completely unrelated to file endings did not appear. The leftover .gitattributes file thus caused some spurious stderr unrelated to the thing being checked. Since other tests did not intend to test normalization, just proactively remove the .gitattributes file. I'm certain this is cleaner and better, I'm just unsure why/how this didn't trigger problems before. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-12-22t1091/t3705: remove 'test-tool read-cache --table'Derrick Stolee
Now that 'git ls-files --sparse' exists, we can use it to verify the state of a sparse index instead of 'test-tool read-cache table'. Replace these usages within t1091-sparse-checkout-builtin.sh and t3705-add-sparse-checkout.sh. The important changes are due to the different output format. In t3705, we need to use the '--stage' output to get a file mode and OID, but it also includes a stage value and drops the object type. This leads to some differences in how we handle looking for specific entries. In t1091, the test focuses on enabling the sparse index, so we do not need the --stage flag to demonstrate how the index changes, and instead can use a diff. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-28add, rm, mv: fix bug that prevents the update of non-sparse dirsMatheus Tavares
These three commands recently learned to avoid updating paths outside the sparse checkout even if they are missing the SKIP_WORKTREE bit. This is done using path_in_sparse_checkout(), which checks whether a given path matches the current list of sparsity rules, similar to what clear_ce_flags() does when we run "git sparse checkout init" or "git sparse-checkout reapply". However, clear_ce_flags() uses a recursive approach, applying the match results from parent directories on paths that get the UNDECIDED result, whereas path_in_sparse_checkout() only attempts to match the full path and immediately considers UNDECIDED as NOT_MATCHED. This makes the function miss matches with leading directories. For example, if the user has the sparsity patterns "!/a" and "b/", add, rm, and mv will fail to update the path "a/b/c" and end up displaying a warning about it being outside the sparse checkout even though it isn't. This problem only occurs in full pattern mode as the pattern matching functions never return UNDECIDED for cone mode. To fix this, replicate the recursive behavior of clear_ce_flags() in path_in_sparse_checkout(), falling back to the parent directory match when a path gets the UNDECIDED result. (If this turns out to be too expensive in some cases, we may want to later add some form of caching to accelerate multiple queries within the same directory. This is not implemented in this patch, though.) Also add two tests for each affected command (add, rm, and mv) to check that they behave correctly with the recursive pattern matching. The first test would previously fail without this patch while the second already succeeded. It is added mostly to make sure that we are not breaking the existing pattern matching for directories that are really sparse, and also as a protection against any future regressions. Two other existing tests had to be changed as well: one test in t3602 checks that "git rm -r <dir>" won't remove sparse entries, but it didn't allow the non-sparse entries inside <dir> to be removed. The other one, in t7002, tested that "git mv" would correctly display a warning message for sparse paths, but it accidentally expected the message to include two non-sparse paths as well. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Acked-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28advice: update message to suggest '--sparse'Derrick Stolee
The previous changes modified the behavior of 'git add', 'git rm', and 'git mv' to not adjust paths outside the sparse-checkout cone, even if they exist in the working tree and their cache entries lack the SKIP_WORKTREE bit. The intention is to warn users that they are doing something potentially dangerous. The '--sparse' option was added to each command to allow careful users the same ability they had before. To improve the discoverability of this new functionality, add a message to advice.updateSparsePath that mentions the existence of the option. The previous set of changes also modified the purpose of this message to include possibly a list of paths instead of only a list of pathspecs. Make the warning message more clear about this new behavior. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28add: update --renormalize to skip sparse pathsDerrick Stolee
We added checks for path_in_sparse_checkout() to portions of 'git add' that add warnings and prevent stagins a modification, but we skipped the --renormalize mode. Update renormalize_tracked_files() to ignore cache entries whose path is outside of the sparse-checkout cone (unless --sparse is provided). Add a test in t3705. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28add: update --chmod to skip sparse pathsDerrick Stolee
We added checks for path_in_sparse_checkout() to portions of 'git add' that add warnings and prevent staging a modification, but we skipped the --chmod mode. Update chmod_pathspec() to ignore cache entries whose path is outside of the sparse-checkout cone (unless --sparse is provided). Add a test in t3705. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28add: implement the --sparse optionDerrick Stolee
We previously modified 'git add' to refuse updating index entries outside of the sparse-checkout cone. This is justified to prevent users from accidentally getting into a confusing state when Git removes those files from the working tree at some later point. Unfortunately, this caused some workflows that were previously possible to become impossible, especially around merge conflicts outside of the sparse-checkout cone. These were documented in tests within t1092. We now re-enable these workflows using a new '--sparse' option to 'git add'. This allows users to signal "Yes, I do know what I'm doing with these files," and accept the consequences of the files leaving the worktree later. We delay updating the advice message until implementing a similar option in 'git rm' and 'git mv'. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-28add: skip tracked paths outside sparse-checkout coneDerrick Stolee
When 'git add' adds a tracked file that is outside of the sparse-checkout cone, it checks the SKIP_WORKTREE bit to see if the file exists outside of the sparse-checkout cone. This is usually correct, except in the case of a merge conflict outside of the cone. Modify add_pathspec_matched_against_index() to be more careful about paths by checking the sparse-checkout patterns in addition to the SKIP_WORKTREE bit. This causes 'git add' to no longer allow files outside of the cone that removed the SKIP_WORKTREE bit due to a merge conflict. With only this change, users will only be able to add the file after adding the file to the sparse-checkout cone. A later change will allow users to force adding even though the file is outside of the sparse-checkout cone. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-09-24t3705: test that 'sparse_entry' is unstagedDerrick Stolee
The tests in t3705-add-sparse-checkout.sh check to see how 'git add' behaves with paths outside the sparse-checkout definition. These currently check to see if a given warning is present but not that the index is not updated with the sparse entries. Add a new 'test_sparse_entry_unstaged' helper to be sure 'git add' is behaving correctly. We need to modify setup_sparse_entry to actually commit the sparse_entry file so it exists at HEAD and as an entry in the index, but its exact contents are not staged in the index. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-08add: warn when asked to update SKIP_WORKTREE entriesMatheus Tavares
`git add` already refrains from updating SKIP_WORKTREE entries, but it silently exits with zero code when it is asked to do so. Instead, let's warn the user and display a hint on how to update these entries. Note that we only warn the user whey they give a pathspec item that matches no eligible path for updating, but it does match one or more SKIP_WORKTREE entries. A warning was chosen over erroring out right away to reproduce the same behavior `add` already exhibits with ignored files. This also allow users to continue their workflow without having to invoke `add` again with only the eligible paths (as those will have already been added). Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-08add: make --chmod and --renormalize honor sparse checkoutsMatheus Tavares
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-04-08t3705: add tests for `git add` in sparse checkoutsMatheus Tavares
We already have a couple tests for `add` with SKIP_WORKTREE entries in t7012, but these only cover the most basic scenarios. As we will be changing how `add` deals with sparse paths in the subsequent commits, let's move these two tests to their own file and add more test cases for different `add` options and situations. This also demonstrates two options that don't currently respect SKIP_WORKTREE entries: `--chmod` and `--renormalize`. Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br> Signed-off-by: Junio C Hamano <gitster@pobox.com>