git-annex/Annex/Queue.hs

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{- git-annex command queue
-
- Copyright 2011-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
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module Annex.Queue (
addCommand,
addFlushAction,
addUpdateIndex,
flush,
flushWhenFull,
size,
get,
mergeFrom,
) where
import Annex.Common
import Annex hiding (new)
import Annex.LockFile
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import qualified Git.Queue
import qualified Git.UpdateIndex
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{- Adds a git command to the queue. -}
addCommand :: [CommandParam] -> String -> [CommandParam] -> [FilePath] -> Annex ()
addCommand commonparams command params files = do
q <- get
store =<< flushWhenFull =<<
(Git.Queue.addCommand commonparams command params files q =<< gitRepo)
add restage log When pointer files need to be restaged, they're first written to the log, and then when the restage operation runs, it reads the log. This way, if the git-annex process is interrupted before it can do the restaging, a later git-annex process can do it. Currently, this lets a git-annex get/drop command be interrupted and then re-ran, and as long as it gets/drops additional files, it will clean up after the interrupted command. But more changes are needed to make it easier to restage after an interrupted process. Kept using the git queue to run the restage action, even though the list of files that it builds up for that action is not actually used by the action. This could perhaps be simplified to make restaging a cleanup action that gets registered, rather than using the git queue for it. But I wasn't sure if that would cause visible behavior changes, when eg dropping a large number of files, currently the git queue flushes periodically, and so it restages incrementally, rather than all at the end. In restagePointerFiles, it reads the restage log twice, once to get the number of files and size, and a second time to process it. This seemed better than reading the whole file into memory, since potentially a huge number of files could be in there. Probably the OS will cache the file in memory and there will not be much performance impact. It might be better to keep running tallies in another file though. But updating that atomically with the log seems hard. Also note that it's possible for calcRestageLog to see a different file than streamRestageLog does. More files may be added to the log in between. That is ok, it will only cause the filterprocessfaster heuristic to operate with slightly out of date information, so it may make the wrong choice for the files that got added and be a little slower than ideal. Sponsored-by: Dartmouth College's DANDI project
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addFlushAction :: Git.Queue.FlushActionRunner Annex -> [RawFilePath] -> Annex ()
addFlushAction runner files = do
q <- get
store =<< flushWhenFull =<<
(Git.Queue.addFlushAction runner files q =<< gitRepo)
{- Adds an update-index stream to the queue. -}
addUpdateIndex :: Git.UpdateIndex.Streamer -> Annex ()
addUpdateIndex streamer = do
q <- get
store =<< flushWhenFull =<<
(Git.Queue.addUpdateIndex streamer q =<< gitRepo)
{- Runs the queue if it is full. -}
flushWhenFull :: Git.Queue.Queue Annex -> Annex (Git.Queue.Queue Annex)
flushWhenFull q
| Git.Queue.full q = flush' q
| otherwise = return q
{- Runs (and empties) the queue. -}
flush :: Annex ()
flush = do
q <- get
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unless (0 == Git.Queue.size q) $ do
store =<< flush' q
{- When there are multiple worker threads, each has its own queue.
- And of course multiple git-annex processes may be running each with its
- own queue.
-
- But, flushing two queues at the same time could lead to failures due to
- git locking files. So, only one queue is allowed to flush at a time.
-}
flush' :: Git.Queue.Queue Annex -> Annex (Git.Queue.Queue Annex)
flush' q = do
lck <- fromRepo gitAnnexGitQueueLock
withExclusiveLock lck $ do
showStoringStateAction
Git.Queue.flush q =<< gitRepo
{- Gets the size of the queue. -}
size :: Annex Int
size = Git.Queue.size <$> get
get :: Annex (Git.Queue.Queue Annex)
get = maybe new return =<< getState repoqueue
new :: Annex (Git.Queue.Queue Annex)
new = do
improve git command queue flushing with time limit So that eg, addurl of several large files that take time to download will update the index for each file, rather than deferring the index updates to the end. In cases like an add of many smallish files, where a new file is being added every few seconds. In that case, the queue will still build up a lot of changes which are flushed at once, for best performance. Since the default queue size is 10240, often it only gets flushed once at the end, same as before. (Notice that updateQueue updated _lastchanged when adding a new item to the queue without flushing it; that is necessary to avoid it flushing the queue every 5 minutes in this case.) But, when it takes more than a 5 minutes to add a file, the overhead of updating the index immediately is probably small, so do it after each file. This avoids git-annex potentially taking a very very long time indeed to stage newly added files, which can be annoying to the user who would like to get on with doing something with the files it's already added, eg using git mv to rename them to a better name. This is only likely to cause a problem if it takes say, 30 seconds to update the index; doing an extra 30 seconds of work after every 5 minute file add would be less optimal. Normally, updating the index takes significantly less time than that. On a SSD with 100k files it takes less than 1 second, and the index write time is bound by disk read and write so is not too much worse on a hard drive. So I hope this will not impact users, although if it does turn out to, the time limit could be made configurable. A perhaps better way to do it would be to have a background worker thread that wakes up every 60 seconds or so and flushes the queue. That is made somewhat difficult because the queue can contain Annex actions and so this would add a new source of concurrency issues. So I'm trying to avoid that approach if possible. Sponsored-by: Erik Bjäreholt on Patreon
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sz <- annexQueueSize <$> getGitConfig
q <- liftIO $ Git.Queue.new sz Nothing
store q
return q
store :: Git.Queue.Queue Annex -> Annex ()
store q = changeState $ \s -> s { repoqueue = Just q }
mergeFrom :: AnnexState -> Annex ()
mergeFrom st = case repoqueue st of
Nothing -> noop
Just newq -> do
q <- get
let !q' = Git.Queue.merge q newq
store =<< flushWhenFull q'