remove overview of threads an mvars

has become too long to be useful, and I find I don't need it anymore
to keep things straight

Assistant.hs

@@ -1,120 +1,8 @@
 {- git-annex assistant daemon
  -
- - Copyright 2012 Joey Hess <joey@kitenet.net>
+ - Copyright 2012-2013 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
- -
- - Overview of threads and MVars, etc:
- -
- - Thread 1: parent
- - 	The initial thread run, double forks to background, starts other
- - 	threads, and then stops, waiting for them to terminate,
- - 	or for a ctrl-c.
- - Thread 2: Watcher
- - 	Notices new files, and calls handlers for events, queuing changes.
- - Thread 3: inotify internal
- - 	Used by haskell inotify library to ensure inotify event buffer is
- - 	kept drained.
- - Thread 4: inotify startup scanner
- - 	Scans the tree and registers inotify watches for each directory.
- -	A MVar lock is used to prevent other inotify handlers from running
- -	until this is complete.
- - Thread 5: Committer
- - 	Waits for changes to occur, and runs the git queue to update its
- - 	index, then commits. Also queues Transfer events to send added
- - 	files to other remotes.
- - Thread 6: Pusher
- - 	Waits for commits to be made, and pushes updated branches to remotes,
- - 	in parallel. (Forks a process for each git push.)
- - Thread 7: PushRetryer
- - 	Runs every 30 minutes when there are failed pushes, and retries
- - 	them.
- - Thread 8: Merger
- - 	Waits for pushes to be received from remotes, and merges the
- - 	updated branches into the current branch.
- - 	(This uses inotify on .git/refs/heads, so there are additional
- - 	inotify threads associated with it, too.)
- - Thread 9: TransferWatcher
- - 	Watches for transfer information files being created and removed,
- - 	and maintains the DaemonStatus currentTransfers map.
- - 	(This uses inotify on .git/annex/transfer/, so there are
- - 	additional inotify threads associated with it, too.)
- - Thread 10: TransferPoller
- -	Polls to determine how much of each ongoing transfer is complete.
- - Thread 11: Transferrer
- - 	Waits for Transfers to be queued and does them.
- - Thread 12: StatusLogger
- - 	Wakes up periodically and records the daemon's status to disk.
- - Thread 13: SanityChecker
- - 	Wakes up periodically (rarely) and does sanity checks.
- - Thread 14: MountWatcher
- - 	Either uses dbus to watch for drive mount events, or, when
- - 	there's no dbus, polls to find newly mounted filesystems.
- - 	Once a filesystem that contains a remote is mounted, updates
- - 	state about that remote, pulls from it, and queues a push to it,
- - 	as well as an update, and queues it onto the
- - 	ConnectedRemoteChan
- - Thread 15: NetWatcher
- - 	Deals with network connection interruptions, which would cause
- - 	transfers to fail, and can be recovered from by waiting for a
- - 	network connection, and syncing with all network remotes.
- - 	Uses dbus to watch for network connections, or when dbus
- - 	cannot be used, assumes there's been one every 30 minutes.
- - Thread 16: TransferScanner
- - 	Does potentially expensive checks to find data that needs to be
- - 	transferred from or to remotes, and queues Transfers.
- - 	Uses the ScanRemotes map.a
- - Thread 17: PairListener
- - 	Listens for incoming pairing traffic, and takes action.
- - Thread 18: ConfigMonitor
- - 	Triggered by changes to the git-annex branch, checks for changed
- - 	config files, and reloads configs.
- - Thread 19: XMPPClient
- - 	Built-in XMPP client.
- - Thread 20: WebApp
- - 	Spawns more threads as necessary to handle clients.
- - 	Displays the DaemonStatus.
- - Thread 21: Glacier
- - 	Deals with retrieving files from Amazon Glacier.
- -
- - ThreadState: (MVar)
- - 	The Annex state is stored here, which allows resuscitating the
- - 	Annex monad in IO actions run by the watcher and committer
- - 	threads. Thus, a single state is shared amoung the threads, and
- - 	only one at a time can access it.
- - DaemonStatusHandle: (STM TMVar)
- - 	The daemon's current status.
- - ChangeChan: (STM TChan)
- - 	Changes are indicated by writing to this channel. The committer
- - 	reads from it.
- - CommitChan: (STM TChan)
- - 	Commits are indicated by writing to this channel. The pusher reads
- - 	from it.
- - FailedPushMap (STM TMVar)
- - 	Failed pushes are indicated by writing to this TMVar. The push
- - 	retrier blocks until they're available.
- - TransferQueue (STM TChan)
- - 	Transfers to make are indicated by writing to this channel.
- - TransferSlots (QSemN)
- - 	Count of the number of currently available transfer slots.
- - 	Updated by the transfer watcher, this allows other threads
- - 	to block until a slot is available.
- - 	This MVar should only be manipulated from inside the Annex monad,
- - 	which ensures it's accessed only after the ThreadState MVar.
- - ScanRemotes (STM TMVar)
- - 	Remotes that have been disconnected, and should be scanned
- - 	are indicated by writing to this TMVar.
- - BranchChanged (STM SampleVar)
- - 	Changes to the git-annex branch are indicated by updating this
- - 	SampleVar.
- - NetMessager (STM TChan, TMVar, SampleVar)
- - 	Used to feed messages to the built-in XMPP client, handle
- - 	pushes, and signal it when it needs to restart due to configuration
- - 	or networking changes.
- - UrlRenderer (MVar)
- - 	A Yesod route rendering function is stored here. This allows
- - 	things that need to render Yesod routes to block until the webapp
- - 	has started up and such rendering is possible.
  -}
 
 {-# LANGUAGE CPP #-}