56 lines
2.5 KiB
Markdown
56 lines
2.5 KiB
Markdown
Seems to me there is a bug in how merges are done in direct mode. This is
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done in two steps:
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1. Merge the remote branch into the local branch, with work tree directed
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to a temp dir.
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2. Use the temp dir and the newly merged branch to update the work tree.
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If this is interrupted between 1 and 2, by eg the user ctrl-Cing or power
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being lost, the result is a repository that thinks the current branch has
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been merged, but does not have an updated work tree. The next sync in that
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repository will see the files as deleted (or as being an old version), and
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commit the current work tree state to the branch.
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Result is files appear to be lost, although `git revert` in an indirect
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mode repo can get them back.
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To fix this, direct mode merge would need to avoid updating the current
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branch when merging the remote branch into it (how?). It should first
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update the whole work tree, and only after it's updated should it update
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the index and the current branch to reflect the merge.
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This way, if the merge is interrupted, the work tree may have uncommitted
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changed -- but it's fine if they get accidentally committed, since when
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the merge is re-done, those changes will by the same ones made by the
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merge. (I assume this is how `git merge` normally works.) --[[Joey]]
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> Implemented that. And then realized that even updating the index
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> as part of a merge results in the work tree being out of sync with the
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> index. Which will cause the next sync to again delete any files that
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> are in the index but not the work tree. Urgh.
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>
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> Seems that a direct mode
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> merge also needs to use a different index file to stage its changes?
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> (Ugh)
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> > done --[[Joey]]
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> > > I had to revert the fix on FAT/Windows due to
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> > > a git bug: <http://marc.info/?l=git&m=140262402204212&w=2>
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> > > Once that bug's fixed, I can revisit this. --[[Joey]]
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[[!meta title="direct mode merge interrupt (fixed for all except FAT, Windows)"]]
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## other options
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> Or could perhaps use `git-merge-tree`
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> and avoid staging the merge in the index until the work-tree is updated.
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>
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> Alternatively, could use another strategy.. Add a lock file which is held while
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> the merge is in progress and contains the pre-merge sha.
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> If the lock file is present but not held, state is inconsistent.
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> `git-annex sync` and the SanityChecker should
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> then run mergeDirectCleanup to recover, before any commits can be made
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> from the inconsistent state. This approach seems to get complicated
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> quickly.. --[[Joey]]
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[[!meta tag=deprecateddirectmode]]
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