224 lines
8.1 KiB
Haskell
224 lines
8.1 KiB
Haskell
{- git-annex assistant daemon
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-
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- Copyright 2012 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-
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- Overview of threads and MVars, etc:
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-
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- Thread 1: parent
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- The initial thread run, double forks to background, starts other
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- threads, and then stops, waiting for them to terminate,
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- or for a ctrl-c.
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- Thread 2: Watcher
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- Notices new files, and calls handlers for events, queuing changes.
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- Thread 3: inotify internal
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- Used by haskell inotify library to ensure inotify event buffer is
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- kept drained.
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- Thread 4: inotify startup scanner
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- Scans the tree and registers inotify watches for each directory.
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- A MVar lock is used to prevent other inotify handlers from running
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- until this is complete.
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- Thread 5: Committer
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- Waits for changes to occur, and runs the git queue to update its
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- index, then commits. Also queues Transfer events to send added
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- files to other remotes.
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- Thread 6: Pusher
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- Waits for commits to be made, and pushes updated branches to remotes,
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- in parallel. (Forks a process for each git push.)
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- Thread 7: PushRetryer
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- Runs every 30 minutes when there are failed pushes, and retries
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- them.
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- Thread 8: Merger
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- Waits for pushes to be received from remotes, and merges the
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- updated branches into the current branch.
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- (This uses inotify on .git/refs/heads, so there are additional
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- inotify threads associated with it, too.)
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- Thread 9: TransferWatcher
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- Watches for transfer information files being created and removed,
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- and maintains the DaemonStatus currentTransfers map.
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- (This uses inotify on .git/annex/transfer/, so there are
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- additional inotify threads associated with it, too.)
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- Thread 10: TransferPoller
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- Polls to determine how much of each ongoing transfer is complete.
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- Thread 11: Transferrer
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- Waits for Transfers to be queued and does them.
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- Thread 12: StatusLogger
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- Wakes up periodically and records the daemon's status to disk.
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- Thread 13: SanityChecker
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- Wakes up periodically (rarely) and does sanity checks.
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- Thread 14: MountWatcher
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- Either uses dbus to watch for drive mount events, or, when
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- there's no dbus, polls to find newly mounted filesystems.
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- Once a filesystem that contains a remote is mounted, updates
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- state about that remote, pulls from it, and queues a push to it,
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- as well as an update, and queues it onto the
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- ConnectedRemoteChan
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- Thread 15: NetWatcher
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- Deals with network connection interruptions, which would cause
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- transfers to fail, and can be recovered from by waiting for a
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- network connection, and syncing with all network remotes.
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- Uses dbus to watch for network connections, or when dbus
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- cannot be used, assumes there's been one every 30 minutes.
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- Thread 16: TransferScanner
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- Does potentially expensive checks to find data that needs to be
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- transferred from or to remotes, and queues Transfers.
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- Uses the ScanRemotes map.a
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- Thread 17: PairListener
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- Listens for incoming pairing traffic, and takes action.
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- Thread 18: ConfigMonitor
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- Triggered by changes to the git-annex branch, checks for changed
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- config files, and reloads configs.
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- Thread 19: XMPPClient
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- Built-in XMPP client.
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- Thread 20: WebApp
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- Spawns more threads as necessary to handle clients.
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- Displays the DaemonStatus.
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- Thread 21: Glacier
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- Deals with retrieving files from Amazon Glacier.
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-
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- ThreadState: (MVar)
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- The Annex state is stored here, which allows resuscitating the
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- Annex monad in IO actions run by the watcher and committer
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- threads. Thus, a single state is shared amoung the threads, and
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- only one at a time can access it.
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- DaemonStatusHandle: (STM TMVar)
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- The daemon's current status.
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- ChangeChan: (STM TChan)
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- Changes are indicated by writing to this channel. The committer
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- reads from it.
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- CommitChan: (STM TChan)
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- Commits are indicated by writing to this channel. The pusher reads
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- from it.
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- FailedPushMap (STM TMVar)
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- Failed pushes are indicated by writing to this TMVar. The push
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- retrier blocks until they're available.
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- TransferQueue (STM TChan)
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- Transfers to make are indicated by writing to this channel.
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- TransferSlots (QSemN)
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- Count of the number of currently available transfer slots.
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- Updated by the transfer watcher, this allows other threads
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- to block until a slot is available.
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- This MVar should only be manipulated from inside the Annex monad,
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- which ensures it's accessed only after the ThreadState MVar.
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- ScanRemotes (STM TMVar)
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- Remotes that have been disconnected, and should be scanned
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- are indicated by writing to this TMVar.
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- BranchChanged (STM SampleVar)
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- Changes to the git-annex branch are indicated by updating this
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- SampleVar.
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- NetMessager (STM TChan, TMVar, SampleVar)
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- Used to feed messages to the built-in XMPP client, handle
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- pushes, and signal it when it needs to restart due to configuration
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- or networking changes.
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- UrlRenderer (MVar)
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- A Yesod route rendering function is stored here. This allows
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- things that need to render Yesod routes to block until the webapp
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- has started up and such rendering is possible.
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-}
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{-# LANGUAGE CPP #-}
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module Assistant where
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import Assistant.Common
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import Assistant.DaemonStatus
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import Assistant.NamedThread
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import Assistant.Types.ThreadedMonad
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import Assistant.Threads.DaemonStatus
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import Assistant.Threads.Watcher
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import Assistant.Threads.Committer
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import Assistant.Threads.Pusher
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import Assistant.Threads.Merger
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import Assistant.Threads.TransferWatcher
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import Assistant.Threads.Transferrer
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import Assistant.Threads.SanityChecker
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import Assistant.Threads.MountWatcher
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import Assistant.Threads.NetWatcher
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import Assistant.Threads.TransferScanner
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import Assistant.Threads.TransferPoller
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import Assistant.Threads.ConfigMonitor
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import Assistant.Threads.Glacier
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#ifdef WITH_WEBAPP
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import Assistant.WebApp
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import Assistant.Threads.WebApp
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#ifdef WITH_PAIRING
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import Assistant.Threads.PairListener
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#endif
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#ifdef WITH_XMPP
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import Assistant.Threads.XMPPClient
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#endif
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#else
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#warning Building without the webapp. You probably need to install Yesod..
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#endif
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import qualified Utility.Daemon
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import Utility.LogFile
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import Utility.ThreadScheduler
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import Control.Concurrent
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type NamedThread = IO () -> IO (String, IO ())
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stopDaemon :: Annex ()
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stopDaemon = liftIO . Utility.Daemon.stopDaemon =<< fromRepo gitAnnexPidFile
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startDaemon :: Bool -> Bool -> Maybe (String -> FilePath -> IO ()) -> Annex ()
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startDaemon assistant foreground webappwaiter
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| foreground = do
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showStart (if assistant then "assistant" else "watch") "."
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liftIO . Utility.Daemon.lockPidFile =<< fromRepo gitAnnexPidFile
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go id
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| otherwise = do
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logfd <- liftIO . openLog =<< fromRepo gitAnnexLogFile
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pidfile <- fromRepo gitAnnexPidFile
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go $ Utility.Daemon.daemonize logfd (Just pidfile) False
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where
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go d = startAssistant assistant d webappwaiter
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startAssistant :: Bool -> (IO () -> IO ()) -> Maybe (String -> FilePath -> IO ()) -> Annex ()
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startAssistant assistant daemonize webappwaiter = withThreadState $ \st -> do
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checkCanWatch
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dstatus <- startDaemonStatus
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liftIO $ daemonize $
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flip runAssistant go =<< newAssistantData st dstatus
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where
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go = do
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d <- getAssistant id
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#ifdef WITH_WEBAPP
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urlrenderer <- liftIO newUrlRenderer
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#endif
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mapM_ (startthread d)
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[ watch $ commitThread
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#ifdef WITH_WEBAPP
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, assist $ webAppThread d urlrenderer False Nothing webappwaiter
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#ifdef WITH_PAIRING
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, assist $ pairListenerThread urlrenderer
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#endif
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#ifdef WITH_XMPP
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, assist $ xmppClientThread urlrenderer
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#endif
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#endif
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, assist $ pushThread
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, assist $ pushRetryThread
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, assist $ mergeThread
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, assist $ transferWatcherThread
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, assist $ transferPollerThread
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, assist $ transfererThread
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, assist $ daemonStatusThread
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, assist $ sanityCheckerThread
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, assist $ mountWatcherThread
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, assist $ netWatcherThread
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, assist $ netWatcherFallbackThread
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, assist $ transferScannerThread
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, assist $ configMonitorThread
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, assist $ glacierThread
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, watch $ watchThread
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]
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liftIO waitForTermination
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watch a = (True, a)
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assist a = (False, a)
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startthread d (watcher, t)
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| watcher || assistant = void $ liftIO $ forkIO $
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runAssistant d $ runNamedThread t
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| otherwise = noop
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