William Sprent via GitGitGadget wrote: > From: William Sprent <williams@xxxxxxxxxxx> > > There is currently no way to ask git the question "which files would be > part of a sparse checkout of commit X with sparse checkout patterns Y". > One use-case would be that tooling may want know whether sparse checkouts > of two commits contain the same content even if the full trees differ. > Another interesting use-case would be for tooling to use in conjunction > with 'git update-index --index-info'. These types of use cases align nicely with "Behavior A" as described in 'Documentation/technical/sparse-checkout.txt' [1]. I think adding a '--scope=(sparse|all)' option to 'ls-trees' would be a good way to make progress on the goals of that design document as well as serve the needs described above. [1] https://lore.kernel.org/git/pull.1367.v4.git.1667714666810.gitgitgadget@xxxxxxxxx/ > > 'rev-list --objects --filter=sparse:oid' comes close, but as rev-list is > concerned with objects rather than directory trees, it leaves files out > when the same blob occurs in at two different paths. > > It is possible to ask git about the sparse status of files currently in > the index with 'ls-files -t'. However, this does not work well when the > caller is interested in another commit, intererested in sparsity > patterns that aren't currently in '.git/info/sparse-checkout', or when > working in with bare repo. I'm a bit confused by your described use cases here, though. Right now, 'sparse-checkout' is a local repo-only optimization (for performance and/or scoping user workspaces), but you seem to be implying a need for "sparse-checkout patterns" as a general-purpose data format (like a config file or 'rebase-todo') that can be used to manually configure command behavior. If that is what you're getting at, it seems like a pretty substantial expansion to the scope of what we consider "sparse checkout". That's not to say it isn't a good idea - I can definitely imagine tooling where this type of functionality is useful - just that it warrants careful consideration so we don't over-complicate the typical sparse-checkout user experience. > > To fill this gap, add a new argument to ls-tree '--sparse-filter-oid' > which takes the object id of a blob containing sparse checkout patterns > that filters the output of 'ls-tree'. When filtering with given sparsity > patterns, 'ls-tree' only outputs blobs and commit objects that > match the given patterns. I don't think a blob OID is the best way to specify an arbitrary pattern set in this case. OIDs will only be created for blobs that are tracked in Git; it's possible that your project tracks potential sparse-checkout patterns in Git, but it seems overly restrictive. You could instead specify the file with a path on-disk (like the '--file' options in various commands, e.g. 'git commit'); if you did need to get that file from the object store, you could first get its contents with 'git cat-file'. > > While it may be valid in some situations to output a tree object -- e.g. > when a cone pattern matches all blobs recursively contained in a tree -- > it is less unclear what should be output if a sparse pattern matches > parts of a tree. > > To allow for reusing the pattern matching logic found in > 'path_in_sparse_checkout_1()' in 'dir.c' with arbitrary patterns, > extract the pattern matching part of the function into its own new > function 'recursively_match_path_with_sparse_patterns()'. > > Signed-off-by: William Sprent <williams@xxxxxxxxxxx> > --- > ls-tree: add --sparse-filter-oid argument > > I'm resubmitting this change as rebased on top of 'master', as it > conflicted with the topic 'ls-tree.c: clean-up works' 1 > [https://public-inbox.org/git/20230112091135.20050-1-tenglong.tl@xxxxxxxxxxxxxxx], > which was merged to 'master' recently. > > This versions also incorporates changes based on the comments made in 2 > [https://public-inbox.org/git/CAPig+cRgZ0CrkqY7mufuWmhf6BC8yXjXXuOTEQjuz+Y0NA+N7Q@xxxxxxxxxxxxxx/]. > > I'm also looping in contributors that have touched ls-tree and/or > sparse-checkouts recently. I hope that's okay. Definitely okay, thanks for CC-ing! Overall, this is an interesting extension to 'sparse-checkout', and opens up some opportunities for expanded tooling. However, at an implementation level, I think it's addressing two separate needs ("constrain 'ls-files' to display files matching patterns" and "specify sparse patterns not in '.git/info/sparse-checkout'") in one option, which makes for a somewhat confusing and inflexible user experience. What about instead breaking this into two options: * --scope=(sparse|all): limits the scope of the files output by ("Behavior A" vs. "Behavior B" from the document linked earlier). * --sparse-patterns=<file>: specifies "override" patterns to use instead of those in '.git/info/sparse-checkout' (whether 'sparse-checkout' is enabled for the repository or not). I haven't looked at your implementation in detail yet, but I did want to offer a recommendation in case you hadn't considered it: if you want to allow the use of patterns from a user-specified specific file, it would be nice to do it in a way that fully replaces the "default" sparse-checkout settings at the lowest level (i.e., override the values of 'core_apply_sparse_checkout', 'core_sparse_checkout_cone', and 'get_sparse_checkout_filename()'). Doing it that way would both make it easier for other commands to add a '--sparse-patterns' option, and avoid the separate code path ('path_in_sparse_checkout_1()' vs. 'recursively_match_path_with_sparse_patterns()', for example) when dealing with '.git/info/sparse-checkout' patterns vs. manually-specified patterns. > > William > > Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1459%2Fwilliams-unity%2Fls-tree-sparse-v2 > Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1459/williams-unity/ls-tree-sparse-v2 > Pull-Request: https://github.com/gitgitgadget/git/pull/1459
