git-annex/Git/Queue.hs
2023-03-17 15:14:58 -04:00

267 lines
8.8 KiB
Haskell

{- git repository command queue
-
- Copyright 2010-2022 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE CPP, BangPatterns #-}
module Git.Queue (
Queue,
new,
defaultTimelimit,
addCommand,
addUpdateIndex,
addFlushAction,
FlushActionRunner(..),
size,
full,
flush,
merge,
) where
import Utility.SafeCommand
import Common
import Git
import Git.Command
import qualified Git.UpdateIndex
import qualified Data.Map.Strict as M
import Control.Monad.IO.Class
import Data.Time.Clock
import Data.Time.Clock.POSIX
{- Queable actions that can be performed in a git repository. -}
data Action m
{- Updating the index file, using a list of streamers that can
- be added to as the queue grows. -}
= UpdateIndexAction [Git.UpdateIndex.Streamer] -- in reverse order
{- A git command to run, on a list of files that can be added to
- as the queue grows. -}
| CommandAction
{ getCommonParams :: [CommandParam]
-- ^ parameters that come before the git subcommand
-- (in addition to the Repo's gitGlobalOpts.
, getSubcommand :: String
, getParams :: [CommandParam]
-- ^ parameters that come after the git subcommand
, getFiles :: [CommandParam]
}
{- A FlushAction can be added along with CommandActions or
- UpdateIndexActions, and when the queue later gets flushed,
- those will be run before the FlushAction is. -}
| FlushAction
{ getFlushActionRunner :: FlushActionRunner m
, getFlushActionFiles :: [RawFilePath]
}
{- The String must be unique for each flush action. -}
data FlushActionRunner m = FlushActionRunner String (Repo -> [RawFilePath] -> m ())
instance Eq (FlushActionRunner m) where
FlushActionRunner s1 _ == FlushActionRunner s2 _ = s1 == s2
{- A key that can uniquely represent an action in a Map.
-
- The ordering controls what order the actions are run in when flushing
- the queue. -}
data ActionKey
= UpdateIndexActionKey
| CommandActionKey [CommandParam] String [CommandParam]
| FlushActionKey String
deriving (Eq, Ord)
actionKey :: Action m -> ActionKey
actionKey (UpdateIndexAction _) = UpdateIndexActionKey
actionKey CommandAction { getCommonParams = c, getSubcommand = s, getParams = p } = CommandActionKey c s p
actionKey FlushAction { getFlushActionRunner = FlushActionRunner s _ } = FlushActionKey s
{- A queue of actions to perform (in any order) on a git repository,
- with lists of files to perform them on. This allows coalescing
- similar git commands. -}
data Queue m = Queue
{ size :: Int
, _limit :: Int
, _timelimit :: NominalDiffTime
, _lastchanged :: POSIXTime
, items :: M.Map ActionKey (Action m)
}
{- A recommended maximum size for the queue, after which it should be
- run.
-
- 10240 is semi-arbitrary. If we assume git filenames are between 10 and
- 255 characters long, then the queue will build up between 100kb and
- 2550kb long commands. The max command line length on linux is somewhere
- above 20k, so this is a fairly good balance -- the queue will buffer
- only a few megabytes of stuff and a minimal number of commands will be
- run by xargs. -}
defaultLimit :: Int
defaultLimit = 10240
{- How close together in seconds changes to the queue have to be happening
- in order for it to keep accumulating actions, rather than running actions
- immediately. -}
defaultTimelimit :: NominalDiffTime
defaultTimelimit = 60 * 5
{- Constructor for empty queue. -}
new :: Maybe Int -> Maybe NominalDiffTime -> IO (Queue m)
new lim tlim = do
now <- getPOSIXTime
return $ Queue 0
(fromMaybe defaultLimit lim)
(fromMaybe defaultTimelimit tlim)
now
M.empty
{- Adds an git command to the queue.
-
- Git commands with the same subcommand but different parameters are
- assumed to be equivalent enough to perform in any order with the same
- end result.
-}
addCommand :: MonadIO m => [CommandParam] -> String -> [CommandParam] -> [FilePath] -> Queue m -> Repo -> m (Queue m)
addCommand commonparams subcommand params files q repo =
updateQueue action conflicting (length files) q repo
where
action = CommandAction
{ getCommonParams = commonparams
, getSubcommand = subcommand
, getParams = params
, getFiles = map File files
}
conflicting (CommandAction { getSubcommand = s }) = s /= subcommand
conflicting (FlushAction {}) = False
conflicting _ = True
{- Adds an flush action to the queue. This can co-exist with anything else
- that gets added to the queue, and when the queue is eventually flushed,
- it will be run after the other things in the queue. -}
addFlushAction :: MonadIO m => FlushActionRunner m -> [RawFilePath] -> Queue m -> Repo -> m (Queue m)
addFlushAction runner files q repo =
updateQueue action (const False) (length files) q repo
where
action = FlushAction
{ getFlushActionRunner = runner
, getFlushActionFiles = files
}
{- Adds an update-index streamer to the queue. -}
addUpdateIndex :: MonadIO m => Git.UpdateIndex.Streamer -> Queue m -> Repo -> m (Queue m)
addUpdateIndex streamer q repo =
updateQueue action conflicting 1 q repo
where
-- the list is built in reverse order
action = UpdateIndexAction [streamer]
conflicting (UpdateIndexAction _) = False
conflicting (FlushAction {}) = False
conflicting _ = True
{- Updates or adds an action in the queue.
-
- If the queue already contains a conflicting action, it will be flushed
- before adding the action; this is to ensure that conflicting actions,
- like add and rm, are run in the right order.
-
- If the queue's time limit has been exceeded, it will also be flushed,
- and the action will be run right away.
-}
updateQueue :: MonadIO m => Action m -> (Action m -> Bool) -> Int -> Queue m -> Repo -> m (Queue m)
updateQueue !action conflicting sizeincrease q repo = do
now <- liftIO getPOSIXTime
if now - (_lastchanged q) > _timelimit q
then if isconflicting
then do
q' <- flush q repo
flush (mk q') repo
else flush (mk q) repo
else if isconflicting
then mk <$> flush q repo
else return $ mk (q { _lastchanged = now })
where
isconflicting = not (null (filter conflicting (M.elems (items q))))
mk q' = newq
where
!newq = q'
{ size = newsize
, items = newitems
}
!newsize = size q' + sizeincrease
!newitems = M.insertWith combineNewOld (actionKey action) action (items q')
{- The new value comes first. It probably has a smaller list of files than
- the old value. So, the list append of the new value first is more
- efficient. -}
combineNewOld :: Action m -> Action m -> Action m
combineNewOld (CommandAction _cps1 _sc1 _ps1 fs1) (CommandAction cps2 sc2 ps2 fs2) =
CommandAction cps2 sc2 ps2 (fs1++fs2)
combineNewOld (UpdateIndexAction s1) (UpdateIndexAction s2) =
UpdateIndexAction (s1++s2)
combineNewOld (FlushAction _r1 fs1) (FlushAction r2 fs2) =
FlushAction r2 (fs1++fs2)
combineNewOld anew _aold = anew
{- Merges the contents of the second queue into the first.
- This should only be used when the two queues are known to contain
- non-conflicting actions. -}
merge :: Queue m -> Queue m -> Queue m
merge origq newq = origq
{ size = size origq + size newq
, items = M.unionWith combineNewOld (items newq) (items origq)
, _lastchanged = max (_lastchanged origq) (_lastchanged newq)
}
{- Is a queue large enough that it should be flushed? -}
full :: Queue m -> Bool
full (Queue cur lim _ _ _) = cur >= lim
{- Runs a queue on a git repository. -}
flush :: MonadIO m => Queue m -> Repo -> m (Queue m)
flush (Queue _ lim tlim _ m) repo = do
forM_ (M.elems m) $ runAction repo
now <- liftIO getPOSIXTime
return $ Queue 0 lim tlim now M.empty
{- Runs an Action on a list of files in a git repository.
-
- Complicated by commandline length limits.
-
- Intentionally runs the command even if the list of files is empty;
- this allows queueing commands that do not need a list of files. -}
runAction :: MonadIO m => Repo -> Action m -> m ()
runAction repo (UpdateIndexAction streamers) =
-- list is stored in reverse order
liftIO $ Git.UpdateIndex.streamUpdateIndex repo $ reverse streamers
runAction repo action@(CommandAction {}) = liftIO $ do
#ifndef mingw32_HOST_OS
let p = (proc "xargs" $ "-0":"git":toCommand gitparams)
{ env = gitEnv repo
, std_in = CreatePipe
}
withCreateProcess p (go p)
#else
-- Using xargs on Windows is problematic, so just run the command
-- once per file (not as efficient.)
if null (getFiles action)
then void $ boolSystemEnv "git" gitparams (gitEnv repo)
else forM_ (getFiles action) $ \f ->
void $ boolSystemEnv "git" (gitparams ++ [f]) (gitEnv repo)
#endif
where
gitparams = gitCommandLine
(getCommonParams action++Param (getSubcommand action):getParams action)
repo
#ifndef mingw32_HOST_OS
go p (Just h) _ _ pid = do
hPutStr h $ intercalate "\0" $ toCommand $ getFiles action
hClose h
forceSuccessProcess p pid
go _ _ _ _ _ = error "internal"
#endif
runAction repo action@(FlushAction {}) =
let FlushActionRunner _ runner = getFlushActionRunner action
in runner repo (getFlushActionFiles action)