squash! hnix-store-remote prototype

use ExceptT, concat logs, utility log functions

hnix-store-remote/src/System/Nix/Store/Remote/Protocol.hs

@@ -7,11 +7,13 @@ module System.Nix.Store.Remote.Protocol (
   , runStore) where
 
 import           Control.Exception         (bracket)
+import           Control.Monad.Except
 import           Control.Monad.Reader
 import           Control.Monad.State
 
 import           Data.Binary.Get
 import           Data.Binary.Put
+import qualified Data.ByteString.Char8     as BSC
 import qualified Data.ByteString.Lazy      as LBS
 
 import           Network.Socket            hiding (send, sendTo, recv, recvFrom)
@@ -114,7 +116,9 @@ simpleOpArgs op args = do
   runOpArgs op args
   err <- gotError
   case err of
-    True -> return False  -- XXX: ErrorT?
+    True -> do
+      Error _num msg <- head <$> getError
+      throwError $ BSC.unpack $ LBS.toStrict msg
     False -> do
       sockGetBool
 
@@ -128,9 +132,13 @@ runOpArgs op args = do
     args
 
   out <- processOutput
-  put out
+  modify (++out)
+  err <- gotError
+  when err $ do
+    Error _num msg <- head <$> getError
+    throwError $ BSC.unpack $ LBS.toStrict msg
 
-runStore :: MonadStore a -> IO (a, [Logger])
+runStore :: MonadStore a -> IO (Either String a, [Logger])
 runStore code = do
   bracket (open sockPath) close run
   where
@@ -152,4 +160,4 @@ runStore code = do
       processOutput
 
     run sock =
-      flip runReaderT sock $ flip runStateT [] (greet >> code)
+      flip runReaderT sock $ flip runStateT [] $ runExceptT (greet >> code)

hnix-store-remote/src/System/Nix/Store/Remote/Types.hs

@@ -2,15 +2,19 @@ module System.Nix.Store.Remote.Types (
     MonadStore
   , Logger(..)
   , Field(..)
-  , gotError) where
+  , getLog
+  , flushLog
+  , gotError
+  , getError) where
 
 
 import qualified Data.ByteString.Lazy      as LBS
 import           Network.Socket            (Socket)
+import           Control.Monad.Except
 import           Control.Monad.Reader
 import           Control.Monad.State
 
-type MonadStore a = StateT [Logger] (ReaderT Socket IO) a
+type MonadStore a = ExceptT String (StateT [Logger] (ReaderT Socket IO)) a
 
 type ActivityID = Int
 type ActivityParentID = Int
@@ -38,3 +42,12 @@ isError _           = False
 
 gotError :: MonadStore Bool
 gotError = any isError <$> get
+
+getError :: MonadStore [Logger]
+getError = filter isError <$> get
+
+getLog :: MonadStore [Logger]
+getLog = get
+
+flushLog :: MonadStore ()
+flushLog = put []