ensure outgoing sync pushes always succeed when repo is accessible

The fallback branches pushed to contain the uuid of the pusher, which is
ugly. That's why syncing doesn't normally use this method.

The merger deletes fallback branches after merging them, to contain the
ugliness, and so unused doesn't look at data from these branches.
(The fallback git-annex branch is left behind for now.)
This commit is contained in:
Joey Hess 2012-09-16 19:48:12 -04:00
parent 6cddda4143
commit ddacbbe798
2 changed files with 73 additions and 24 deletions

View file

@ -17,10 +17,12 @@ import qualified Command.Sync
import Utility.Parallel
import qualified Git
import qualified Git.Branch
import qualified Git.Ref
import qualified Git.Command
import qualified Remote
import qualified Types.Remote as Remote
import qualified Annex.Branch
import Annex.UUID
import Data.Time.Clock
import qualified Data.Map as M
@ -56,48 +58,89 @@ reconnectRemotes threadname st dstatus scanremotes rs = void $
return (True, diverged)
{- Updates the local sync branch, then pushes it to all remotes, in
- parallel.
- parallel, along with the git-annex branch. This is the same
- as "git annex sync", except in parallel, and will co-exist with use of
- "git annex sync".
-
- Avoids running possibly long-duration commands in the Annex monad, so
- as not to block other threads. -}
- as not to block other threads.
-
- This can fail, when the remote's sync branch (or git-annex branch) has
- been updated by some other remote pushing into it, or by the remote
- itself. To handle failure, a manual pull and merge is done, and the push
- is retried.
-
- When there's a lot of activity, we may fail more than once.
- On the other hand, we may fail because the remote is not available.
- Rather than retrying indefinitely, after the first retry we enter a
- fallback mode, where our push is guarenteed to succeed if the remote is
- reachable. If the fallback fails, the push is queued to be retried
- later.
-
- The fallback mode pushes to branches on the remote that have our uuid in
- them. While ugly, those branches are reserved for pushing by us, and
- so our pushes will succeed.
-}
pushToRemotes :: ThreadName -> UTCTime -> ThreadState -> Maybe FailedPushMap -> [Remote] -> IO Bool
pushToRemotes threadname now st mpushmap remotes = do
(g, branch) <- runThreadState st $
(,) <$> fromRepo id <*> inRepo Git.Branch.current
go True branch g remotes
(g, branch, u) <- runThreadState st $ (,,)
<$> fromRepo id
<*> inRepo Git.Branch.current
<*> getUUID
go True branch g u remotes
where
go _ Nothing _ _ = return True -- no branch, so nothing to do
go shouldretry (Just branch) g rs = do
go _ Nothing _ _ _ = return True -- no branch, so nothing to do
go shouldretry (Just branch) g u rs = do
debug threadname
[ "pushing to"
, show rs
]
Command.Sync.updateBranch (Command.Sync.syncBranch branch) g
(succeeded, failed) <- inParallel (push g branch) rs
updatemap succeeded []
let ok = null failed
case mpushmap of
Nothing -> noop
Just pushmap ->
changeFailedPushMap pushmap $ \m ->
M.union (makemap failed) $
M.difference m (makemap succeeded)
unless ok $
debug threadname
[ "failed to push to"
, show failed
]
if ok || not shouldretry
if ok
then return ok
else retry branch g failed
else if shouldretry
then retry branch g u failed
else fallback branch g u failed
updatemap succeeded failed = case mpushmap of
Nothing -> noop
Just pushmap -> changeFailedPushMap pushmap $ \m ->
M.union (makemap failed) $
M.difference m (makemap succeeded)
makemap l = M.fromList $ zip l (repeat now)
push g branch remote = Command.Sync.pushBranch remote branch g
retry branch g rs = do
retry branch g u rs = do
debug threadname [ "trying manual pull to resolve failed pushes" ]
void $ manualPull st (Just branch) rs
go False (Just branch) g rs
go False (Just branch) g u rs
fallback branch g u rs = do
debug threadname
[ "fallback pushing to"
, show rs
]
(succeeded, failed) <- inParallel (pushfallback g u branch) rs
updatemap succeeded failed
return $ null failed
push g branch remote = Command.Sync.pushBranch remote branch g
pushfallback g u branch remote = Git.Command.runBool "push"
[ Param $ Remote.name remote
, Param $ refspec Annex.Branch.name
, Param $ refspec branch
] g
where
refspec b = concat
[ s
, ":"
, show $ Git.Ref.base $
Command.Sync.syncBranch $ Git.Ref $
"fallback" </> fromUUID u </> s
]
where s = show $ Git.Ref.base b
{- Manually pull from remotes and merge their branches. -}
manualPull :: ThreadState -> Maybe Git.Ref -> [Remote] -> IO Bool

View file

@ -15,6 +15,7 @@ import qualified Annex.Branch
import qualified Git
import qualified Git.Merge
import qualified Git.Branch
import qualified Git.Command as Git
thisThread :: ThreadName
thisThread = "Merger"
@ -81,6 +82,11 @@ onAdd g file _
, show current
]
void $ Git.Merge.mergeNonInteractive changedbranch g
when ("fallback/" `isInfixOf` (show changedbranch)) $
void $ Git.runBool "branch"
[ Param "-D"
, Param $ show changedbranch
] g
go _ = noop
equivBranches :: Git.Ref -> Git.Ref -> Bool