
We add the ability to filter the object types in the path-walk API so the callback function is called fewer times. This adds the ability to ask for the commits in a list, as well. We re-use the empty string for this set of objects because these are passed directly to the callback function instead of being part of the 'path_stack'. Future changes will add the ability to visit annotated tags. Signed-off-by: Derrick Stolee <stolee@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
56 lines
2.1 KiB
Plaintext
56 lines
2.1 KiB
Plaintext
Path-Walk API
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=============
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The path-walk API is used to walk reachable objects, but to visit objects
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in batches based on a common path they appear in, or by type.
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For example, all reachable commits are visited in a group. All tags are
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visited in a group. Then, all root trees are visited. At some point, all
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blobs reachable via a path `my/dir/to/A` are visited. When there are
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multiple paths possible to reach the same object, then only one of those
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paths is used to visit the object.
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Basics
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------
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To use the path-walk API, include `path-walk.h` and call
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`walk_objects_by_path()` with a customized `path_walk_info` struct. The
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struct is used to set all of the options for how the walk should proceed.
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Let's dig into the different options and their use.
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`path_fn` and `path_fn_data`::
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The most important option is the `path_fn` option, which is a
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function pointer to the callback that can execute logic on the
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object IDs for objects grouped by type and path. This function
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also receives a `data` value that corresponds to the
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`path_fn_data` member, for providing custom data structures to
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this callback function.
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`revs`::
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To configure the exact details of the reachable set of objects,
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use the `revs` member and initialize it using the revision
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machinery in `revision.h`. Initialize `revs` using calls such as
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`setup_revisions()` or `parse_revision_opt()`. Do not call
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`prepare_revision_walk()`, as that will be called within
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`walk_objects_by_path()`.
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+
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It is also important that you do not specify the `--objects` flag for the
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`revs` struct. The revision walk should only be used to walk commits, and
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the objects will be walked in a separate way based on those starting
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commits.
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`commits`, `blobs`, `trees`::
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By default, these members are enabled and signal that the path-walk
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API should call the `path_fn` on objects of these types. Specialized
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applications could disable some options to make it simpler to walk
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the objects or to have fewer calls to `path_fn`.
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+
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While it is possible to walk only commits in this way, consumers would be
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better off using the revision walk API instead.
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Examples
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--------
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See example usages in:
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`t/helper/test-path-walk.c`
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