On 2022-03-01 at 22:20:33, Taylor Blau wrote: > When renaming a remote, Git needs to rename all remote tracking > references to the remote's new name (e.g., renaming > "refs/remotes/old/foo" to "refs/remotes/new/foo" when renaming a remote > from "old" to "new"). > > This can be somewhat slow when there are many references to rename, > since each rename is done in a separate call to rename_ref() as opposed > to grouping all renames together into the same transaction. It would be > nice to execute all renames as a single transaction, but there is a > snag: the reference transaction backend doesn't support renames during a > transaction (only individually, via rename_ref()). > > The reasons there are described in more detail in [1], but the main > problem is that in order to preserve the existing reflog, it must be > moved while holding both locks (i.e., on "oldname" and "newname"), and > the ref transaction code doesn't support inserting arbitrary actions > into the middle of a transaction like that. > > As an aside, adding support for this to the ref transaction code is > less straightforward than inserting both a ref_update() and ref_delete() > call into the same transaction. rename_ref()'s special handling to > detect D/F conflicts would need to be rewritten for the transaction code > if we wanted to proactively catch D/F conflicts when renaming a > reference during a transaction. The reftable backend could support this > much more readily because of its lack of D/F conflicts. > > Instead of a more complex modification to the ref transaction code, > display a progress meter when running verbosely in order to convince the > user that Git is doing work while renaming a remote. > > This is mostly done as-expected, with the minor caveat that we > intentionally count symrefs renames twice, since renaming a symref takes > place over two separate calls (one to delete the old one, and another to > create the new one). > > [1]: https://lore.kernel.org/git/572367B4.4050207@xxxxxxxxxxxx/ > > Suggested-by: brian m. carlson <sandals@xxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Taylor Blau <me@xxxxxxxxxxxx> As I mentioned to you personally, I think this looks good. For context, I discovered this when I tried to rename a remote with tens of thousands of branches and it just ran silently for an extended period of time without any output. I actually interrupted it with Ctrl-C because I thought it had hung, so I'm hoping this will provide a better experience for users in that situation. -- brian m. carlson (he/him or they/them) Toronto, Ontario, CA
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