git-annex/Annex/Action.hs
Joey Hess ba7ecbc6a9
avoid flushing keys db queue after each Annex action
The flush was only done Annex.run' to make sure that the queue was flushed
before git-annex exits. But, doing it there means that as soon as one
change gets queued, it gets flushed soon after, which contributes to
excessive writes to the database, slowing git-annex down.
(This does not yet speed git-annex up, but it is a stepping stone to
doing so.)

Database queues do not autoflush when garbage collected, so have to
be flushed explicitly. I don't think it's possible to make them
autoflush (except perhaps if git-annex sqitched to using ResourceT..).
The comment in Database.Keys.closeDb used to be accurate, since the
automatic flushing did mean that all writes reached the database even
when closeDb was not called. But now, closeDb or flushDb needs to be
called before stopping using an Annex state. So, removed that comment.

In Remote.Git, change to using quiesce everywhere that it used to use
stopCoProcesses. This means that uses on onLocal in there are just as
slow as before. I considered only calling closeDb on the local git remotes
when git-annex exits. But, the reason that Remote.Git calls stopCoProcesses
in each onLocal is so as not to leave git processes running that have files
open on the remote repo, when it's on removable media. So, it seemed to make
sense to also closeDb after each one, since sqlite may also keep files
open. Although that has not seemed to cause problems with removable
media so far. It was also just easier to quiesce in each onLocal than
once at the end. This does likely leave performance on the floor, so
could be revisited.

In Annex.Content.saveState, there was no reason to close the db,
flushing it is enough.

The rest of the changes are from auditing for Annex.new, and making
sure that quiesce is called, after any action that might possibly need
it.

After that audit, I'm pretty sure that the change to Annex.run' is
safe. The only concern might be that this does let more changes get
queued for write to the db, and if git-annex is interrupted, those will be
lost. But interrupting git-annex can obviously already prevent it from
writing the most recent change to the db, so it must recover from such
lost data... right?

Sponsored-by: Dartmouth College's Datalad project
2022-10-12 14:12:23 -04:00

105 lines
2.5 KiB
Haskell

{- git-annex actions
-
- Copyright 2010-2022 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.Action (
action,
verifiedAction,
startup,
quiesce,
stopCoProcesses,
) where
import qualified Data.Map as M
import Annex.Common
import qualified Annex
import Annex.Content
import Annex.CatFile
import Annex.CheckAttr
import Annex.HashObject
import Annex.CheckIgnore
import Annex.TransferrerPool
import qualified Database.Keys
import Control.Concurrent.STM
#ifndef mingw32_HOST_OS
import System.Posix.Signals
#endif
{- Runs an action that may throw exceptions, catching and displaying them. -}
action :: Annex () -> Annex Bool
action a = tryNonAsync a >>= \case
Right () -> return True
Left e -> do
warning (show e)
return False
verifiedAction :: Annex Verification -> Annex (Bool, Verification)
verifiedAction a = tryNonAsync a >>= \case
Right v -> return (True, v)
Left e -> do
warning (show e)
return (False, UnVerified)
{- Actions to perform each time ran. -}
startup :: Annex ()
startup = do
#ifndef mingw32_HOST_OS
av <- Annex.getRead Annex.signalactions
let propagate sig = liftIO $ installhandleronce sig av
propagate sigINT
propagate sigQUIT
propagate sigTERM
propagate sigTSTP
propagate sigCONT
propagate sigHUP
-- sigWINCH is not propagated; it should not be needed,
-- and the concurrent-output library installs its own signal
-- handler for it.
-- sigSTOP and sigKILL cannot be caught, so will not be propagated.
where
installhandleronce sig av = void $
installHandler sig (CatchOnce (gotsignal sig av)) Nothing
gotsignal sig av = do
mapM_ (\a -> a (fromIntegral sig)) =<< atomically (readTVar av)
raiseSignal sig
installhandleronce sig av
#else
return ()
#endif
{- Rn all cleanup actions, save all state, stop all long-running child
- processes.
-
- This can be run repeatedly with other Annex actions run in between,
- but usually it is run only once at the end.
-
- When passed True, avoids making any commits to the git-annex branch,
- leaving changes in the journal for later commit.
-}
quiesce :: Bool -> Annex ()
quiesce nocommit = do
cas <- Annex.withState $ \st -> return
( st { Annex.cleanupactions = mempty }
, Annex.cleanupactions st
)
sequence_ (M.elems cas)
saveState nocommit
stopCoProcesses
Database.Keys.closeDb
{- Stops all long-running child processes, including git query processes. -}
stopCoProcesses :: Annex ()
stopCoProcesses = do
catFileStop
checkAttrStop
hashObjectStop
checkIgnoreStop
emptyTransferrerPool