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{-# LANGUAGE ExistentialQuantification #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE NondecreasingIndentation #-}
module Announcer
( Announcer
, AnnounceKey
, packAnnounceKey
, unpackAnnounceKey
, AnnounceMethod(..)
, forkAnnouncer
, stopAnnouncer
, schedule
, cancel
) where
import Data.Wrapper.PSQ as PSQ
import Network.Kademlia.Search
import InterruptibleDelay
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
| Announce (IO ()) POSIXTime
| DeleteAnnouncement
| SearchFinished
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
atomically $ readTVar (announcerActive announcer) >>= check . not
data AnnounceMethod r = forall nid ni addr r tok a. AnnounceMethod
{ aSearch :: Search nid addr tok ni r
, aPublish :: r -> tok -> Maybe ni -> IO (Maybe a)
}
schedule :: Announcer -> AnnounceKey -> AnnounceMethod r -> r -> IO ()
schedule announcer k _ _ = do
let announce = _todo :: IO () -- publish to current search results
search = _todo :: IO () -- thread to fork
interval = _todo :: POSIXTime -- publish interval
atomically $ scheduleImmediately announcer k $ NewAnnouncement search announce interval
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
interruptDelay (interrutible announcer)
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 _) -> return $ Just $ return ()
|
