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module Erebos.Service (
Service(..),
SomeService(..), someService, someServiceAttr, someServiceID,
SomeServiceState(..), fromServiceState, someServiceEmptyState,
SomeServiceGlobalState(..), fromServiceGlobalState, someServiceEmptyGlobalState,
SomeStorageWatcher(..),
ServiceID, mkServiceID,
ServiceHandler,
ServiceInput(..),
ServiceReply(..),
runServiceHandler,
svcGet, svcSet, svcModify,
svcGetGlobal, svcSetGlobal, svcModifyGlobal,
svcGetLocal, svcSetLocal,
svcSelf,
svcPrint,
replyPacket, replyStored, replyStoredRef,
afterCommit,
) where
import Control.Monad.Except
import Control.Monad.Reader
import Control.Monad.State
import Control.Monad.Writer
import Data.Kind
import Data.Typeable
import Data.UUID (UUID)
import qualified Data.UUID as U
import Erebos.Identity
import {-# SOURCE #-} Erebos.Network
import Erebos.State
import Erebos.Storable
import Erebos.Storage.Head
class (Typeable s, Storable s, Typeable (ServiceState s), Typeable (ServiceGlobalState s)) => Service s where
serviceID :: proxy s -> ServiceID
serviceHandler :: Stored s -> ServiceHandler s ()
serviceNewPeer :: ServiceHandler s ()
serviceNewPeer = return ()
type ServiceAttributes s = attr | attr -> s
type ServiceAttributes s = Proxy s
defaultServiceAttributes :: proxy s -> ServiceAttributes s
default defaultServiceAttributes :: ServiceAttributes s ~ Proxy s => proxy s -> ServiceAttributes s
defaultServiceAttributes _ = Proxy
type ServiceState s :: Type
type ServiceState s = ()
emptyServiceState :: proxy s -> ServiceState s
default emptyServiceState :: ServiceState s ~ () => proxy s -> ServiceState s
emptyServiceState _ = ()
type ServiceGlobalState s :: Type
type ServiceGlobalState s = ()
emptyServiceGlobalState :: proxy s -> ServiceGlobalState s
default emptyServiceGlobalState :: ServiceGlobalState s ~ () => proxy s -> ServiceGlobalState s
emptyServiceGlobalState _ = ()
serviceStorageWatchers :: proxy s -> [SomeStorageWatcher s]
serviceStorageWatchers _ = []
data SomeService = forall s. Service s => SomeService (Proxy s) (ServiceAttributes s)
someService :: forall s proxy. Service s => proxy s -> SomeService
someService _ = SomeService @s Proxy (defaultServiceAttributes @s Proxy)
someServiceAttr :: forall s. Service s => ServiceAttributes s -> SomeService
someServiceAttr attr = SomeService @s Proxy attr
someServiceID :: SomeService -> ServiceID
someServiceID (SomeService s _) = serviceID s
data SomeServiceState = forall s. Service s => SomeServiceState (Proxy s) (ServiceState s)
fromServiceState :: Service s => proxy s -> SomeServiceState -> Maybe (ServiceState s)
fromServiceState _ (SomeServiceState _ s) = cast s
someServiceEmptyState :: SomeService -> SomeServiceState
someServiceEmptyState (SomeService p _) = SomeServiceState p (emptyServiceState p)
data SomeServiceGlobalState = forall s. Service s => SomeServiceGlobalState (Proxy s) (ServiceGlobalState s)
fromServiceGlobalState :: Service s => proxy s -> SomeServiceGlobalState -> Maybe (ServiceGlobalState s)
fromServiceGlobalState _ (SomeServiceGlobalState _ s) = cast s
someServiceEmptyGlobalState :: SomeService -> SomeServiceGlobalState
someServiceEmptyGlobalState (SomeService p _) = SomeServiceGlobalState p (emptyServiceGlobalState p)
data SomeStorageWatcher s = forall a. Eq a => SomeStorageWatcher (Stored LocalState -> a) (a -> ServiceHandler s ())
newtype ServiceID = ServiceID UUID
deriving (Eq, Ord, Show, StorableUUID)
mkServiceID :: String -> ServiceID
mkServiceID = maybe (error "Invalid service ID") ServiceID . U.fromString
data ServiceInput s = ServiceInput
{ svcAttributes :: ServiceAttributes s
, svcPeer :: Peer
, svcPeerIdentity :: UnifiedIdentity
, svcServer :: Server
, svcPrintOp :: String -> IO ()
}
data ServiceReply s = ServiceReply (Either s (Stored s)) Bool
| ServiceFinally (IO ())
data ServiceHandlerState s = ServiceHandlerState
{ svcValue :: ServiceState s
, svcGlobal :: ServiceGlobalState s
, svcLocal :: Stored LocalState
}
newtype ServiceHandler s a = ServiceHandler (ReaderT (ServiceInput s) (WriterT [ServiceReply s] (StateT (ServiceHandlerState s) (ExceptT String IO))) a)
deriving (Functor, Applicative, Monad, MonadReader (ServiceInput s), MonadWriter [ServiceReply s], MonadState (ServiceHandlerState s), MonadError String, MonadIO)
instance MonadStorage (ServiceHandler s) where
getStorage = asks $ peerStorage . svcPeer
instance MonadHead LocalState (ServiceHandler s) where
updateLocalHead f = do
(ls, x) <- f =<< gets svcLocal
modify $ \s -> s { svcLocal = ls }
return x
runServiceHandler :: Service s => Head LocalState -> ServiceInput s -> ServiceState s -> ServiceGlobalState s -> ServiceHandler s () -> IO ([ServiceReply s], (ServiceState s, ServiceGlobalState s))
runServiceHandler h input svc global shandler = do
let sstate = ServiceHandlerState { svcValue = svc, svcGlobal = global, svcLocal = headStoredObject h }
ServiceHandler handler = shandler
(runExceptT $ flip runStateT sstate $ execWriterT $ flip runReaderT input $ handler) >>= \case
Left err -> do
svcPrintOp input $ "service failed: " ++ err
return ([], (svc, global))
Right (rsp, sstate')
| svcLocal sstate' == svcLocal sstate -> return (rsp, (svcValue sstate', svcGlobal sstate'))
| otherwise -> replaceHead h (svcLocal sstate') >>= \case
Left (Just h') -> runServiceHandler h' input svc global shandler
_ -> return (rsp, (svcValue sstate', svcGlobal sstate'))
svcGet :: ServiceHandler s (ServiceState s)
svcGet = gets svcValue
svcSet :: ServiceState s -> ServiceHandler s ()
svcSet x = modify $ \st -> st { svcValue = x }
svcModify :: (ServiceState s -> ServiceState s) -> ServiceHandler s ()
svcModify f = modify $ \st -> st { svcValue = f (svcValue st) }
svcGetGlobal :: ServiceHandler s (ServiceGlobalState s)
svcGetGlobal = gets svcGlobal
svcSetGlobal :: ServiceGlobalState s -> ServiceHandler s ()
svcSetGlobal x = modify $ \st -> st { svcGlobal = x }
svcModifyGlobal :: (ServiceGlobalState s -> ServiceGlobalState s) -> ServiceHandler s ()
svcModifyGlobal f = modify $ \st -> st { svcGlobal = f (svcGlobal st) }
svcGetLocal :: ServiceHandler s (Stored LocalState)
svcGetLocal = gets svcLocal
svcSetLocal :: Stored LocalState -> ServiceHandler s ()
svcSetLocal x = modify $ \st -> st { svcLocal = x }
svcSelf :: ServiceHandler s UnifiedIdentity
svcSelf = maybe (throwError "failed to validate own identity") return .
validateExtendedIdentity . lsIdentity . fromStored =<< svcGetLocal
svcPrint :: String -> ServiceHandler s ()
svcPrint str = afterCommit . ($ str) =<< asks svcPrintOp
replyPacket :: Service s => s -> ServiceHandler s ()
replyPacket x = tell [ServiceReply (Left x) True]
replyStored :: Service s => Stored s -> ServiceHandler s ()
replyStored x = tell [ServiceReply (Right x) True]
replyStoredRef :: Service s => Stored s -> ServiceHandler s ()
replyStoredRef x = tell [ServiceReply (Right x) False]
afterCommit :: IO () -> ServiceHandler s ()
afterCommit x = tell [ServiceFinally x]
|