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55 lines
2.2 KiB
55 lines
2.2 KiB
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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The basic idea is to write the SHA1s of shallow commits into |
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$GIT_DIR/shallow, and handle its contents like the contents |
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of $GIT_DIR/info/grafts (with the difference that shallow |
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cannot contain parent information). |
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This information is stored in a new file instead of grafts, or |
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even the config, since the user should not touch that file |
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at all (even throughout development of the shallow clone, it |
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was never manually edited!). |
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Each line contains exactly one SHA1. 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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