git-annex/Assistant/Monad.hs
Joey Hess 2e0e557e75
Support being built with ghc 8.0.1 (MonadFail)
Tested on an older ghc by enabling MonadFailDesugaring globally.

In TransferQueue, the lack of a MonadFail for STM exposed what would
normally be a bug in the pattern matching, although in this case an
earlier check that the queue was not empty avoided a pattern match
failure.
2019-01-05 11:55:15 -04:00

150 lines
4 KiB
Haskell

{- git-annex assistant monad
-
- Copyright 2012 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE GeneralizedNewtypeDeriving, MultiParamTypeClasses #-}
module Assistant.Monad (
Assistant,
AssistantData(..),
newAssistantData,
runAssistant,
getAssistant,
LiftAnnex,
liftAnnex,
(<~>),
(<<~),
asIO,
asIO1,
asIO2,
ThreadName,
debug,
notice
) where
import "mtl" Control.Monad.Reader
import System.Log.Logger
import qualified Control.Monad.Fail as Fail
import Annex.Common
import Assistant.Types.ThreadedMonad
import Assistant.Types.DaemonStatus
import Assistant.Types.ScanRemotes
import Assistant.Types.TransferQueue
import Assistant.Types.TransferSlots
import Assistant.Types.TransferrerPool
import Assistant.Types.Pushes
import Assistant.Types.BranchChange
import Assistant.Types.Commits
import Assistant.Types.Changes
import Assistant.Types.RepoProblem
import Assistant.Types.ThreadName
import Assistant.Types.RemoteControl
import Assistant.Types.CredPairCache
newtype Assistant a = Assistant { mkAssistant :: ReaderT AssistantData IO a }
deriving (
Monad,
MonadIO,
MonadReader AssistantData,
Fail.MonadFail,
Functor,
Applicative
)
data AssistantData = AssistantData
{ threadName :: ThreadName
, threadState :: ThreadState
, daemonStatusHandle :: DaemonStatusHandle
, scanRemoteMap :: ScanRemoteMap
, transferQueue :: TransferQueue
, transferSlots :: TransferSlots
, transferrerPool :: TransferrerPool
, failedPushMap :: FailedPushMap
, failedExportMap :: FailedPushMap
, commitChan :: CommitChan
, exportCommitChan :: CommitChan
, changePool :: ChangePool
, repoProblemChan :: RepoProblemChan
, branchChangeHandle :: BranchChangeHandle
, remoteControl :: RemoteControl
, credPairCache :: CredPairCache
}
newAssistantData :: ThreadState -> DaemonStatusHandle -> IO AssistantData
newAssistantData st dstatus = AssistantData
<$> pure (ThreadName "main")
<*> pure st
<*> pure dstatus
<*> newScanRemoteMap
<*> newTransferQueue
<*> newTransferSlots
<*> newTransferrerPool (checkNetworkConnections dstatus)
<*> newFailedPushMap
<*> newFailedPushMap
<*> newCommitChan
<*> newCommitChan
<*> newChangePool
<*> newRepoProblemChan
<*> newBranchChangeHandle
<*> newRemoteControl
<*> newCredPairCache
runAssistant :: AssistantData -> Assistant a -> IO a
runAssistant d a = runReaderT (mkAssistant a) d
getAssistant :: (AssistantData -> a) -> Assistant a
getAssistant = reader
{- Using a type class for lifting into the annex monad allows
- easily lifting to it from multiple different monads. -}
class LiftAnnex m where
liftAnnex :: Annex a -> m a
{- Runs an action in the git-annex monad. Note that the same monad state
- is shared among all assistant threads, so only one of these can run at
- a time. Therefore, long-duration actions should be avoided. -}
instance LiftAnnex Assistant where
liftAnnex a = do
st <- reader threadState
liftIO $ runThreadState st a
{- Runs an IO action, passing it an IO action that runs an Assistant action. -}
(<~>) :: (IO a -> IO b) -> Assistant a -> Assistant b
io <~> a = do
d <- reader id
liftIO $ io $ runAssistant d a
{- Creates an IO action that will run an Assistant action when run. -}
asIO :: Assistant a -> Assistant (IO a)
asIO a = do
d <- reader id
return $ runAssistant d a
asIO1 :: (a -> Assistant b) -> Assistant (a -> IO b)
asIO1 a = do
d <- reader id
return $ \v -> runAssistant d $ a v
asIO2 :: (a -> b -> Assistant c) -> Assistant (a -> b -> IO c)
asIO2 a = do
d <- reader id
return $ \v1 v2 -> runAssistant d (a v1 v2)
{- Runs an IO action on a selected field of the AssistantData. -}
(<<~) :: (a -> IO b) -> (AssistantData -> a) -> Assistant b
io <<~ v = reader v >>= liftIO . io
debug :: [String] -> Assistant ()
debug = logaction debugM
notice :: [String] -> Assistant ()
notice = logaction noticeM
logaction :: (String -> String -> IO ()) -> [String] -> Assistant ()
logaction a ws = do
ThreadName name <- getAssistant threadName
liftIO $ a name $ unwords $ (name ++ ":") : ws