30 lines
1.5 KiB
Text
30 lines
1.5 KiB
Text
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When git-annex is updating the git-annex branch, it currently
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uses a separate index file. This adds overhead and complexity to the code.
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Especially when there are many files, the index file gets large and writing
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it gets slow.
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It might be an improvement to use `git mktree --batch` to inject a
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tree object into git, without using the index file. `git hash-object`
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is already used to add the files to git. All that would be needed is to
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generate an updated tree containing the new file(s), and then update each
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parent tree up to the root tree. This new tree can then be committed using
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`git commit-tree`
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The only thing I can see that might make this slow at all is reading the old
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tree contents, in order to update it. This would need a `git ls-tree` for
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each tree; it does not have a batch mode, so 4 processes would need to be
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spawned when generating a tree that changes 1 file. For any repo that's not
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very small, that's probably still faster than rewriting the index file.
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Notes:
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* The union merge code currently uses the index. No particular reason
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it needs to; that's just how the code is written, and it might be a large
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rewrite to change it.
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* A new git-annex branch can be pushed into the repository at any time.
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The current code uses the index to detect when this happens, and
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union merges the new branch head into the index. Would need something
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like a `GIT_ANNEX_HEAD` ref to do the same if the index is removed.
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Thanks to sm for indirectly suggesting this. --[[Joey]]
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