8d0d81a9ca
Now that grafts are deprecated, we should start to assume that readers have no idea what grafts are. So it makes more sense to make the description of the "shallow" feature stand on its own. Suggested-by: Eric Sunshine <sunshine@sunshineco.com> Helped-by: Junio Hamano <gitster@pobox.com> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
54 lines
2.1 KiB
Plaintext
54 lines
2.1 KiB
Plaintext
Shallow commits
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===============
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.Definition
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*********************************************************
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Shallow commits do have parents, but not in the shallow
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repo, and therefore grafts are introduced pretending that
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these commits have no parents.
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*********************************************************
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$GIT_DIR/shallow lists commit object names and tells Git to
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pretend as if they are root commits (e.g. "git log" traversal
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stops after showing them; "git fsck" does not complain saying
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the commits listed on their "parent" lines do not exist).
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Each line contains exactly one SHA-1. When read, a commit_graft
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will be constructed, which has nr_parent < 0 to make it easier
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to discern from user provided grafts.
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Since fsck-objects relies on the library to read the objects,
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it honours shallow commits automatically.
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There are some unfinished ends of the whole shallow business:
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- maybe we have to force non-thin packs when fetching into a
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shallow repo (ATM they are forced non-thin).
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- A special handling of a shallow upstream is needed. At some
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stage, upload-pack has to check if it sends a shallow commit,
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and it should send that information early (or fail, if the
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client does not support shallow repositories). There is no
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support at all for this in this patch series.
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- Instead of locking $GIT_DIR/shallow at the start, just
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the timestamp of it is noted, and when it comes to writing it,
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a check is performed if the mtime is still the same, dying if
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it is not.
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- It is unclear how "push into/from a shallow repo" should behave.
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- If you deepen a history, you'd want to get the tags of the
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newly stored (but older!) commits. This does not work right now.
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To make a shallow clone, you can call "git-clone --depth 20 repo".
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The result contains only commit chains with a length of at most 20.
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It also writes an appropriate $GIT_DIR/shallow.
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You can deepen a shallow repository with "git-fetch --depth 20
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repo branch", which will fetch branch from repo, but stop at depth
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20, updating $GIT_DIR/shallow.
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The special depth 2147483647 (or 0x7fffffff, the largest positive
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number a signed 32-bit integer can contain) means infinite depth.
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