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https://github.com/ceph/ceph
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45 lines
1.8 KiB
Plaintext
45 lines
1.8 KiB
Plaintext
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Some libraries that Ceph uses are incorporated into the build tree
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through a technique known as git subtrees. This is an alternative to
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git submodules, that is also used in Ceph.
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One such library is the dmclock library. Here are some basic notes on
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the use of git subtrees.
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When a subtree is added to the repo, commands such as these were run
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from the top-level ceph directory:
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git subtree add --prefix src/dmclock \
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git@github.com:ceph/dmclock.git master --squash
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That essentially brings in a full copy of the library into the
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subdirectory src/dmclock, but squashes all the commits into a single
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one.
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If in time the library is updated and you'd like to bring the updates
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in, you could run:
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git subtree pull --prefix src/dmclock \
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git@github.com:ceph/dmclock.git master --squash
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WARNINGS
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If you'd like to modify the library contained in a subtree it's likely
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best to modify it in the library's repo and then pull in the changes
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with "git subtree pull ..." (see above).
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IMPORTANT: If you modify the library within the ceph tree, then do NOT
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combined changes within the subtree and outside the subtree in a
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single commit. Each commit should either only contain changes within
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the subtree or outside the subtree. That gives you the option to
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cleanly push those changes back to the library's repo.
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IMPORTANT: If you do a rebase and the commits that are redone include
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the commits that encapsulate a "git subtree add ..." or "git subtree
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pull ..." you have to be VERY CAREFUL. Those commits lose the prefix
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and try to apply the changes to the wrong paths! Instead, you
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essentially have to do the rebase interactively, remove the commits
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for the subtree add/pull, and manually re-do them between the other
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commits. Some developers prefer not to even do a "git rebase ..." and
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instead cherry-pick the commits and manually do the subtree
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adds/pulls.
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