git-annex/Remote/External/AsyncExtension.hs
Joey Hess 63839532c9
remove uses of warningIO
It's not concurrent-output safe, and doesn't support
--json-error-messages.

Using Annex.makeRunner is a bit scary, because what if it's run in a
different thread from an active annex action? Normally the same Annex
state is not used concurrently in several threads, and it's not designed
to be fully concurrency safe. (Annex.Concurrent exists to deal with
that.) I think it will be ok in these simple cases though. Eg,
when buffering a warning message to json, Annex.changeState is used,
and it modifies the MVar in a concurrency safe way.

The only warningIO remaining is not a problem.
2020-12-02 14:57:43 -04:00

131 lines
4.4 KiB
Haskell

{- External remote protocol async extension.
-
- Copyright 2020 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE BangPatterns #-}
module Remote.External.AsyncExtension (runRelayToExternalAsync) where
import Common
import Annex
import Messages
import Remote.External.Types
import qualified Utility.SimpleProtocol as Proto
import Control.Concurrent.Async
import Control.Concurrent.STM
import Control.Concurrent.STM.TBMChan
import qualified Data.Map.Strict as M
-- | Starts a thread that will handle all communication with the external
-- process. The input ExternalState communicates directly with the external
-- process.
runRelayToExternalAsync :: External -> ExternalState -> (Annex () -> IO ()) -> IO ExternalAsyncRelay
runRelayToExternalAsync external st annexrunner = do
jidmap <- newTVarIO M.empty
sendq <- newSendQueue
nextjid <- newTVarIO (JobId 1)
sender <- async $ sendloop st sendq
receiver <- async $ receiveloop external st jidmap sendq sender annexrunner
return $ ExternalAsyncRelay $ do
receiveq <- newReceiveQueue
jid <- atomically $ do
jid@(JobId n) <- readTVar nextjid
let !jid' = JobId (succ n)
writeTVar nextjid jid'
modifyTVar' jidmap $ M.insert jid receiveq
return jid
return $ ExternalState
{ externalSend = \msg ->
atomically $ writeTBMChan sendq
(toAsyncWrapped msg, jid)
, externalReceive = atomically (readTBMChan receiveq)
-- This shuts down the whole relay.
, externalShutdown = shutdown external st sendq sender receiver
-- These three TMVars are shared amoung all
-- ExternalStates that use this relay; they're
-- common state about the external process.
, externalPrepared = externalPrepared st
, externalConfig = externalConfig st
, externalConfigChanges = externalConfigChanges st
}
type ReceiveQueue = TBMChan String
type SendQueue = TBMChan (AsyncWrapped, JobId)
type JidMap = TVar (M.Map JobId ReceiveQueue)
newReceiveQueue :: IO ReceiveQueue
newReceiveQueue = newTBMChanIO 10
newSendQueue :: IO SendQueue
newSendQueue = newTBMChanIO 10
receiveloop :: External -> ExternalState -> JidMap -> SendQueue -> Async () -> (Annex () -> IO ()) -> IO ()
receiveloop external st jidmap sendq sendthread annexrunner = externalReceive st >>= \case
Just l -> case parseMessage l :: Maybe AsyncMessage of
Just (AsyncMessage jid msg) ->
M.lookup jid <$> readTVarIO jidmap >>= \case
Just c -> do
atomically $ writeTBMChan c msg
receiveloop external st jidmap sendq sendthread annexrunner
Nothing -> protoerr "unknown job number"
Nothing -> case parseMessage l :: Maybe ExceptionalMessage of
Just _ -> do
-- ERROR is relayed to all listeners
m <- readTVarIO jidmap
forM_ (M.elems m) $ \c ->
atomically $ writeTBMChan c l
receiveloop external st jidmap sendq sendthread annexrunner
Nothing -> protoerr "unexpected non-async message"
Nothing -> closeandshutdown
where
protoerr s = do
annexrunner $ warning $ "async external special remote protocol error: " ++ s
closeandshutdown
closeandshutdown = do
dummy <- async noop
shutdown external st sendq sendthread dummy True
m <- atomically $ readTVar jidmap
forM_ (M.elems m) (atomically . closeTBMChan)
sendloop :: ExternalState -> SendQueue -> IO ()
sendloop st sendq = atomically (readTBMChan sendq) >>= \case
Just (wrappedmsg, jid) -> do
case wrappedmsg of
AsyncWrappedRemoteResponse msg ->
externalSend st $ wrapjid msg jid
AsyncWrappedRequest msg ->
externalSend st $ wrapjid msg jid
AsyncWrappedExceptionalMessage msg ->
externalSend st msg
AsyncWrappedAsyncMessage msg ->
externalSend st msg
sendloop st sendq
Nothing -> return ()
where
wrapjid msg jid = AsyncMessage jid $ unwords $ Proto.formatMessage msg
shutdown :: External -> ExternalState -> SendQueue -> Async () -> Async () -> Bool -> IO ()
shutdown external st sendq sendthread receivethread b = do
-- Receive thread is normally blocked reading from a handle.
-- That can block closing the handle, so it needs to be canceled.
cancel receivethread
-- Cleanly shutdown the send thread as well, allowing it to finish
-- writing anything that was buffered.
atomically $ closeTBMChan sendq
wait sendthread
r <- atomically $ do
r <- tryTakeTMVar (externalAsync external)
putTMVar (externalAsync external)
UncheckedExternalAsync
return r
case r of
Just (ExternalAsync _) -> externalShutdown st b
_ -> noop