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{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE NondecreasingIndentation #-}
module Announcer
( Announcer
, AnnounceKey
, packAnnounceKey
, unpackAnnounceKey
, AnnounceMethod(..)
, forkAnnouncer
, stopAnnouncer
, schedule
, cancel
) where
import qualified Data.MinMaxPSQ as MM
import Data.Wrapper.PSQ as PSQ
import InterruptibleDelay
import Network.Kademlia.Routing as R
import Network.Kademlia.Search
import Control.Concurrent.Lifted.Instrument
import Control.Concurrent.STM
import Control.Monad
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as Char8
import Data.Function
import Data.Hashable
import Data.Maybe
import Data.Time.Clock.POSIX
newtype AnnounceKey = AnnounceKey ByteString
deriving (Hashable,Ord,Eq)
packAnnounceKey :: Announcer -> String -> STM AnnounceKey
packAnnounceKey _ = return . AnnounceKey . Char8.pack
unpackAnnounceKey :: AnnounceKey -> AnnounceKey -> STM String
unpackAnnounceKey _ (AnnounceKey bs) = return $ Char8.unpack bs
data ScheduledItem
= forall r. ScheduledItem (AnnounceMethod r)
| StopAnnouncer
| NewAnnouncement (IO ()) (IO ()) POSIXTime
| SearchFinished (IO ()) (IO ()) POSIXTime
| Announce (IO ()) POSIXTime
| DeleteAnnouncement
data Announcer = Announcer
{ scheduled :: TVar (PSQ' AnnounceKey POSIXTime ScheduledItem)
, announcerActive :: TVar Bool
, interrutible :: InterruptibleDelay
}
scheduleImmediately :: Announcer -> AnnounceKey -> ScheduledItem -> STM ()
scheduleImmediately announcer k item
= modifyTVar' (scheduled announcer) (PSQ.insert' k item 0)
stopAnnouncer :: Announcer -> IO ()
stopAnnouncer announcer = do
atomically $ scheduleImmediately announcer (AnnounceKey "*stop*") StopAnnouncer
interruptDelay (interrutible announcer)
atomically $ readTVar (announcerActive announcer) >>= check . not
data AnnounceMethod r = forall nid ni sr addr tok a.
( Show nid
, Hashable nid
, Hashable ni
, Ord addr
, Ord nid
, Ord ni
) => AnnounceMethod
{ aSearch :: Search nid addr tok ni sr
, aPublish :: r -> tok -> Maybe ni -> IO (Maybe a)
, aBuckets :: TVar (R.BucketList ni)
, aTarget :: nid
, aInterval :: POSIXTime
}
schedule :: Announcer -> AnnounceKey -> AnnounceMethod r -> r -> IO ()
schedule announcer k AnnounceMethod{aSearch,aPublish,aBuckets,aTarget,aInterval} r = do
st <- atomically $ newSearch aSearch aTarget []
let announce = do -- publish to current search results
is <- atomically $ do
bs <- readTVar (searchInformant st {- :: TVar (MinMaxPSQ' ni nid tok -})
return $ MM.toList bs
forM_ is $ \(Binding ni mtok _) -> do
forM_ mtok $ \tok -> do
aPublish r tok (Just ni)
return ()
onResult _ = return True -- action for each search-hit (True = keep searching)
search = do -- thread to fork
atomically $ reset aBuckets aSearch aTarget st
searchLoop aSearch aTarget onResult st
atomically $ scheduleImmediately announcer k
$ SearchFinished {- st -} search announce aInterval
interruptDelay (interrutible announcer)
atomically $ scheduleImmediately announcer k $ NewAnnouncement search announce aInterval
interruptDelay (interrutible announcer)
cancel :: Announcer -> AnnounceKey -> AnnounceMethod r -> r -> IO ()
cancel announcer k _ _ = do
atomically $ scheduleImmediately announcer k $ DeleteAnnouncement
interruptDelay (interrutible announcer)
forkAnnouncer :: IO Announcer
forkAnnouncer = do
delay <- interruptibleDelay
announcer <- atomically $ Announcer <$> newTVar PSQ.empty
<*> newTVar True
<*> pure delay
fork $ announceThread announcer
return announcer
announceThread :: Announcer -> IO ()
announceThread announcer = do
myThreadId >>= flip labelThread "announcer"
fix $ \loop -> do
join $ atomically $ do
item <- maybe retry return =<< findMin <$> readTVar (scheduled announcer)
return $ do
now <- getPOSIXTime
-- Is it time to do something?
if (prio item < now)
then do -- Yes. Dequeue and handle this event.
action <- atomically $ do
modifyTVar' (scheduled announcer)
(PSQ.delete (key item))
performScheduledItem announcer now item
-- Are we finished?
mapM_ (>> loop) -- No? Okay, perform scheduled op and loop.
action
else do -- No. Wait a bit.
startDelay (interrutible announcer) (microseconds $ prio item - now)
loop
-- We're done. Let 'stopAnnouncer' know that it can stop blocking.
atomically $ writeTVar (announcerActive announcer) False
performScheduledItem :: Announcer -> POSIXTime -> Binding' AnnounceKey POSIXTime ScheduledItem -> STM (Maybe (IO ()))
performScheduledItem announcer now = \case
(Binding _ StopAnnouncer _) -> return Nothing
-- announcement started:
(Binding k (NewAnnouncement search announce interval) _) -> do
modifyTVar (scheduled announcer)
(PSQ.insert' k (Announce announce interval) (now + interval))
return $ Just $ do
fork search
return ()
-- announcement removed:
(Binding k DeleteAnnouncement _) -> return $ Just $ return ()
-- time for periodic announce:
-- (re-)announce to the current known set of storing-nodes.
-- TODO: If the search is finished, restart the search.
(Binding k (Announce announce interval) _) -> do
modifyTVar (scheduled announcer)
(PSQ.insert' k (Announce announce interval) (now + interval))
return $ Just announce
-- search finished:
-- if any of the current storing-nodes set have not been
-- announced to, announce to them.
(Binding _ (SearchFinished {- st -} search announce interval) _) -> return $ Just $ return ()
|
