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|
{- git-annex assistant out of band network messager interface
-
- Copyright 2012-2013 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
module Assistant.NetMessager where
import Assistant.Common
import Assistant.Types.NetMessager
import Control.Concurrent.STM
import Control.Concurrent.MSampleVar
import qualified Data.Set as S
import qualified Data.Map as M
import qualified Data.DList as D
sendNetMessage :: NetMessage -> Assistant ()
sendNetMessage m =
(atomically . flip writeTChan m) <<~ (netMessages . netMessager)
waitNetMessage :: Assistant (NetMessage)
waitNetMessage = (atomically . readTChan) <<~ (netMessages . netMessager)
notifyNetMessagerRestart :: Assistant ()
notifyNetMessagerRestart =
flip writeSV () <<~ (netMessagerRestart . netMessager)
{- This can be used to get an early indication if the network has
- changed, to immediately restart a connection. However, that is not
- available on all systems, so clients also need to deal with
- restarting dropped connections in the usual way. -}
waitNetMessagerRestart :: Assistant ()
waitNetMessagerRestart = readSV <<~ (netMessagerRestart . netMessager)
{- Store a new important NetMessage for a client, and if an equivilant
- older message is already stored, remove it from both importantNetMessages
- and sentImportantNetMessages. -}
storeImportantNetMessage :: NetMessage -> ClientID -> (ClientID -> Bool) -> Assistant ()
storeImportantNetMessage m client matchingclient = go <<~ netMessager
where
go nm = atomically $ do
q <- takeTMVar $ importantNetMessages nm
sent <- takeTMVar $ sentImportantNetMessages nm
putTMVar (importantNetMessages nm) $
M.alter (Just . maybe (S.singleton m) (S.insert m)) client $
M.mapWithKey removematching q
putTMVar (sentImportantNetMessages nm) $
M.mapWithKey removematching sent
removematching someclient s
| matchingclient someclient = S.filter (not . equivilantImportantNetMessages m) s
| otherwise = s
{- Indicates that an important NetMessage has been sent to a client. -}
sentImportantNetMessage :: NetMessage -> ClientID -> Assistant ()
sentImportantNetMessage m client = go <<~ (sentImportantNetMessages . netMessager)
where
go v = atomically $ do
sent <- takeTMVar v
putTMVar v $
M.alter (Just . maybe (S.singleton m) (S.insert m)) client sent
{- Checks for important NetMessages that have been stored for a client, and
- sent to a client. Typically the same client for both, although
- a modified or more specific client may need to be used. -}
checkImportantNetMessages :: (ClientID, ClientID) -> Assistant (S.Set NetMessage, S.Set NetMessage)
checkImportantNetMessages (storedclient, sentclient) = go <<~ netMessager
where
go nm = atomically $ do
stored <- M.lookup storedclient <$> (readTMVar $ importantNetMessages nm)
sent <- M.lookup sentclient <$> (readTMVar $ sentImportantNetMessages nm)
return (fromMaybe S.empty stored, fromMaybe S.empty sent)
{- Queues a push initiation message in the queue for the appropriate
- side of the push but only if there is not already an initiation message
- from the same client in the queue. -}
queuePushInitiation :: NetMessage -> Assistant ()
queuePushInitiation msg@(Pushing clientid stage) = do
tv <- getPushInitiationQueue side
liftIO $ atomically $ do
r <- tryTakeTMVar tv
case r of
Nothing -> putTMVar tv [msg]
Just l -> do
let !l' = msg : filter differentclient l
putTMVar tv l'
where
side = pushDestinationSide stage
differentclient (Pushing cid _) = cid /= clientid
differentclient _ = True
queuePushInitiation _ = noop
{- Waits for a push inititation message to be received, and runs
- function to select a message from the queue. -}
waitPushInitiation :: PushSide -> ([NetMessage] -> (NetMessage, [NetMessage])) -> Assistant NetMessage
waitPushInitiation side selector = do
tv <- getPushInitiationQueue side
liftIO $ atomically $ do
q <- takeTMVar tv
if null q
then retry
else do
let (msg, !q') = selector q
unless (null q') $
putTMVar tv q'
return msg
{- Stores messages for a push into the appropriate inbox.
-
- To avoid overflow, only 1000 messages max are stored in any
- inbox, which should be far more than necessary.
-
- TODO: If we have more than 100 inboxes for different clients,
- discard old ones that are not currently being used by any push.
-}
storeInbox :: NetMessage -> Assistant ()
storeInbox msg@(Pushing clientid stage) = do
inboxes <- getInboxes side
stored <- liftIO $ atomically $ do
m <- readTVar inboxes
let update = \v -> do
writeTVar inboxes $
M.insertWith' const clientid v m
return True
case M.lookup clientid m of
Nothing -> update (1, tostore)
Just (sz, l)
| sz > 1000 -> return False
| otherwise ->
let !sz' = sz + 1
!l' = D.append l tostore
in update (sz', l')
if stored
then netMessagerDebug clientid ["stored", logNetMessage msg, "in", show side, "inbox"]
else netMessagerDebug clientid ["discarded", logNetMessage msg, "; ", show side, "inbox is full"]
where
side = pushDestinationSide stage
tostore = D.singleton msg
storeInbox _ = noop
{- Gets the new message for a push from its inbox.
- Blocks until a message has been received. -}
waitInbox :: ClientID -> PushSide -> Assistant (NetMessage)
waitInbox clientid side = do
inboxes <- getInboxes side
liftIO $ atomically $ do
m <- readTVar inboxes
case M.lookup clientid m of
Nothing -> retry
Just (sz, dl)
| sz < 1 -> retry
| otherwise -> do
let msg = D.head dl
let dl' = D.tail dl
let !sz' = sz - 1
writeTVar inboxes $
M.insertWith' const clientid (sz', dl') m
return msg
emptyInbox :: ClientID -> PushSide -> Assistant ()
emptyInbox clientid side = do
inboxes <- getInboxes side
liftIO $ atomically $
modifyTVar' inboxes $
M.delete clientid
getInboxes :: PushSide -> Assistant Inboxes
getInboxes side =
getSide side . netMessagerInboxes <$> getAssistant netMessager
getPushInitiationQueue :: PushSide -> Assistant (TMVar [NetMessage])
getPushInitiationQueue side =
getSide side . netMessagerPushInitiations <$> getAssistant netMessager
netMessagerDebug :: ClientID -> [String] -> Assistant ()
netMessagerDebug clientid l = debug $
"NetMessager" : l ++ [show $ logClientID clientid]
|
