sync: Pushes the git-annex branch to remote/synced/git-annex, rather than directly to remote/git-annex.

This fixes a problem I was seeing in the assistant where two remotes would
attempt to sync with one another at the same time, and both failed pushing
the diverged git-annex branch. Then when both tried to resolve the failed
push, they each modified their git-annex branch, which again each blocked
the other from pushing into it. The result was that the git-annex
branches were perpetually diverged (despite having the same content!) and
once the assistant fell into this trap, it couldn't get out and always
had to do the slow push/fail/pull/merge/push/fail cycle.
This commit is contained in:
Joey Hess 2012-09-16 17:54:12 -04:00
parent e61512f42d
commit 601ee470af
4 changed files with 42 additions and 9 deletions

View file

@ -154,15 +154,15 @@ pushRemote remote branch = go =<< needpush
pushBranch :: Remote -> Git.Ref -> Git.Repo -> IO Bool
pushBranch remote branch g =
Git.Command.runBool "push"
[ Param (Remote.name remote)
, Param (show Annex.Branch.name)
, Param refspec
[ Param $ Remote.name remote
, Param $ refspec Annex.Branch.name
, Param $ refspec branch
] g
where
refspec = concat
[ show $ Git.Ref.base branch
refspec b = concat
[ show $ Git.Ref.base b
, ":"
, show $ Git.Ref.base $ syncBranch branch
, show $ Git.Ref.base $ syncBranch b
]
mergeAnnex :: CommandStart

2
debian/changelog vendored
View file

@ -22,6 +22,8 @@ git-annex (3.20120826) UNRELEASED; urgency=low
rather than moving to .git/annex/bad/
* Avoid crashing on encoding errors in filenames when writing transfer info
files and reading from checksum commands.
* sync: Pushes the git-annex branch to remote/synced/git-annex, rather
than directly to remote/git-annex.
-- Joey Hess <joeyh@debian.org> Mon, 27 Aug 2012 13:27:39 -0400

View file

@ -9,8 +9,37 @@ all the other git clones, at both the git level and the key/value level.
(in a fresh clone each time) several times in a row, but then stops happening,
which has prevented me from debugging it.
This could possibly have been caused by the bug fixed in 750c4ac6c282d14d19f79e0711f858367da145e4.
* The git repository syncing sometimes fails due to the remote having updated.
While syncing retries, this sometimes doesn't work.
* The transfer code doesn't always manage to transfer file contents.
Besides reconnection events, there are two places where transfers get queued:
1. When the committer commits a file, it queues uploads.
2. When the watcher sees a broken symlink be created, it queues downloads.
Consider a doubly-linked chain of three repositories, A B and C.
(C and A do not directly communicate.)
* File is added to A.
* A uploads its content to B.
* At the same time, A git syncs to B.
* Once B gets the git sync, it git syncs to C.
* When C's watcher sees the file appear, it tries to download it. But if
B had not finished receiving the file from A, C doesn't know B has it,
and cannot download it from anywhere.
Possible solution: After B receives content, it could queue uploads of it
to all remotes that it doesn't know have it yet, which would include C.
In practice, this has the problem that when C receives the content,
it will queue uploads of it, which can send back to B (or to some other repo
that already has the content) and loop, until the git-annex branches catch
up and break the cycle.
Possible solution: C could record a download intent. (Similar to a failed
download, but with an unknown source.) When C next receives a git-annex
branch push, it could try to requeue downloads that it has such intents
registered for.
## TODO

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@ -5,4 +5,6 @@ that then has to be auto-resolved.
This seems similar to the laddering problem described in this old bug:
[[bugs/making_annex-merge_try_a_fast-forward]]
--[[Joey]]
--[[Joey]]
Think I've fixed this. [[done]] --[[Joey]]