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|
{- git-annex assistant change tracking and committing
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-}
module Assistant.Committer where
import Common.Annex
import Assistant.ThreadedMonad
import qualified Annex.Queue
import qualified Git.Command
import qualified Command.Add
import Utility.ThreadScheduler
import qualified Utility.Lsof as Lsof
import Types.Backend
import Control.Concurrent.STM
import Data.Time.Clock
import Data.Tuple.Utils
import qualified Data.Set as S
data ChangeType = PendingAddChange | LinkChange | RmChange | RmDirChange
deriving (Show, Eq)
type ChangeChan = TChan Change
data Change = Change
{ changeTime :: UTCTime
, changeFile :: FilePath
, changeType :: ChangeType
}
deriving (Show)
runChangeChan :: STM a -> IO a
runChangeChan = atomically
newChangeChan :: IO ChangeChan
newChangeChan = atomically newTChan
{- Handlers call this when they made a change that needs to get committed. -}
madeChange :: FilePath -> ChangeType -> Annex (Maybe Change)
madeChange f t = do
-- Just in case the commit thread is not flushing the queue fast enough.
when (t /= PendingAddChange) $
Annex.Queue.flushWhenFull
liftIO $ Just <$> (Change <$> getCurrentTime <*> pure f <*> pure t)
noChange :: Annex (Maybe Change)
noChange = return Nothing
{- Gets all unhandled changes.
- Blocks until at least one change is made. -}
getChanges :: ChangeChan -> IO [Change]
getChanges chan = runChangeChan $ do
c <- readTChan chan
go [c]
where
go l = do
v <- tryReadTChan chan
case v of
Nothing -> return l
Just c -> go (c:l)
{- Puts unhandled changes back into the channel.
- Note: Original order is not preserved. -}
refillChanges :: ChangeChan -> [Change] -> IO ()
refillChanges chan cs = runChangeChan $ mapM_ (writeTChan chan) cs
{- This thread makes git commits at appropriate times. -}
commitThread :: ThreadState -> ChangeChan -> IO ()
commitThread st changechan = runEvery (Seconds 1) $ do
-- We already waited one second as a simple rate limiter.
-- Next, wait until at least one change has been made.
cs <- getChanges changechan
-- Now see if now's a good time to commit.
time <- getCurrentTime
if shouldCommit time cs
then do
handleAdds st changechan cs
void $ tryIO $ runThreadState st commitStaged
else refillChanges changechan cs
commitStaged :: Annex ()
commitStaged = do
Annex.Queue.flush
inRepo $ Git.Command.run "commit"
[ Param "--allow-empty-message"
, Param "-m", Param ""
-- Empty commits may be made if tree changes cancel
-- each other out, etc
, Param "--allow-empty"
-- Avoid running the usual git-annex pre-commit hook;
-- watch does the same symlink fixing, and we don't want
-- to deal with unlocked files in these commits.
, Param "--quiet"
]
{- Decide if now is a good time to make a commit.
- Note that the list of change times has an undefined order.
-
- Current strategy: If there have been 10 changes within the past second,
- a batch activity is taking place, so wait for later.
-}
shouldCommit :: UTCTime -> [Change] -> Bool
shouldCommit now changes
| len == 0 = False
| len > 10000 = True -- avoid bloating queue too much
| length (filter thisSecond changes) < 10 = True
| otherwise = False -- batch activity
where
len = length changes
thisSecond c = now `diffUTCTime` changeTime c <= 1
{- If there are PendingAddChanges, the files have not yet actually been
- added to the annex (probably), and that has to be done now, before
- committing.
-
- Deferring the adds to this point causes batches to be bundled together,
- which allows faster checking with lsof that the files are not still open
- for write by some other process.
-
- When a file is added, Inotify will notice the new symlink. So this waits
- for additional Changes to arrive, so that the symlink has hopefully been
- staged before returning, and will be committed.
-}
handleAdds :: ThreadState -> ChangeChan -> [Change] -> IO ()
handleAdds st changechan cs
| null toadd = noop
| otherwise = do
toadd' <- safeToAdd st toadd
unless (null toadd') $ do
added <- filter id <$> forM toadd' add
unless (null added) $
handleAdds st changechan =<< getChanges changechan
where
toadd = map changeFile $ filter isPendingAdd cs
isPendingAdd (Change { changeType = PendingAddChange }) = True
isPendingAdd _ = False
add keysource = catchBoolIO $ runThreadState st $ do
showStart "add" $ keyFilename keysource
handle (keyFilename keysource)
=<< Command.Add.ingest keysource
handle _ Nothing = do
showEndFail
return False
handle file (Just key) = do
Command.Add.link file key True
showEndOk
return True
{- Checks which of a set of files can safely be added.
- Files are locked down as hard links in a temp directory,
- with their write bits disabled. But some may have already
- been opened for write, so lsof is run on the temp directory
- to check them.
-}
safeToAdd :: ThreadState -> [FilePath] -> IO [KeySource]
safeToAdd st files = do
locked <- catMaybes <$> lockdown files
runThreadState st $ do
tmpdir <- fromRepo gitAnnexTmpDir
open <- S.fromList . map fst3 . filter openwrite <$>
liftIO (Lsof.queryDir tmpdir)
catMaybes <$> forM locked (go open)
where
go open keysource
| S.member (contentLocation keysource) open = do
warning $ keyFilename keysource
++ " still has writers, not adding"
-- remove the hard link
--_ <- liftIO $ tryIO $
-- removeFile $ contentLocation keysource
return Nothing
| otherwise = return $ Just keysource
lockdown = mapM $ \file -> do
ms <- catchMaybeIO $ getSymbolicLinkStatus file
case ms of
Just s
| isRegularFile s ->
catchMaybeIO $ runThreadState st $
Command.Add.lockDown file
_ -> return Nothing
openwrite (_file, mode, _pid) =
mode == Lsof.OpenWriteOnly || mode == Lsof.OpenReadWrite
|
