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authorGravatar Joey Hess <joey@kitenet.net>2013-05-22 13:10:54 -0400
committerGravatar Joey Hess <joey@kitenet.net>2013-05-22 13:10:54 -0400
commitdcbb9c33d5e82beb32a1068924f467d968ce9611 (patch)
tree3038293eca50007fb9c6c074ebd2aba6ae4640ec /Assistant.hs
parentcd44bfb832996c68d80697c0711db402ffa4334e (diff)
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
Diffstat (limited to 'Assistant.hs')
-rw-r--r--Assistant.hs114
1 files changed, 1 insertions, 113 deletions
diff --git a/Assistant.hs b/Assistant.hs
index b5e902d56..36fef049d 100644
--- a/Assistant.hs
+++ b/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 #-}