From 4701a91c029983b3259a968b31845679aff3da4b Mon Sep 17 00:00:00 2001
From: Patrick Thomson <patrickt@github.com>
Date: Thu, 31 Jan 2019 14:37:40 -0500
Subject: [PATCH] move SQL stuff out of Core and add Catch effect

---
 semantic.cabal              |  1 +
 src/Control/Effect/Catch.hs | 62 +++++++++++++++++++++++++++++++++++++
 src/Semantic/Task.hs        | 14 ++++-----
 3 files changed, 70 insertions(+), 7 deletions(-)
 create mode 100644 src/Control/Effect/Catch.hs

diff --git a/semantic.cabal b/semantic.cabal
index e453c075a..cfe3605e6 100644
--- a/semantic.cabal
+++ b/semantic.cabal
@@ -48,6 +48,7 @@ library
                      , Control.Abstract.ScopeGraph
                      , Control.Abstract.Value
                      -- Effects
+                     , Control.Effect.Catch
                      , Control.Effect.Interpose
                      , Control.Effect.REPL
                      , Control.Rewriting
diff --git a/src/Control/Effect/Catch.hs b/src/Control/Effect/Catch.hs
new file mode 100644
index 000000000..2c23e059f
--- /dev/null
+++ b/src/Control/Effect/Catch.hs
@@ -0,0 +1,62 @@
+{-# LANGUAGE DeriveFunctor, ExistentialQuantification, FlexibleContexts, FlexibleInstances, LambdaCase,
+             MultiParamTypeClasses, RankNTypes, StandaloneDeriving, TypeOperators, UndecidableInstances #-}
+
+-- | An effect that enables catching exceptions thrown from
+-- impure computations such as IO.
+module Control.Effect.Catch
+  ( Catch (..)
+  , catch
+  , runCatch
+  , CatchC (..)
+  ) where
+
+import           Control.Effect.Carrier
+import           Control.Effect.Internal
+import           Control.Effect.Sum
+import qualified Control.Exception as Exc
+import           Control.Monad.IO.Class
+
+data Catch m k
+  = forall output e . Exc.Exception e => CatchIO (m output) (e -> m output) (output -> k)
+
+deriving instance Functor (Catch m)
+
+instance HFunctor Catch where
+  hmap f (CatchIO go cleanup k) = CatchIO (f go) (f . cleanup) k
+
+instance Effect Catch where
+  handle state handler (CatchIO go cleanup k)
+    = CatchIO (handler (go <$ state)) (\se -> handler (cleanup se <$ state)) (handler . fmap k)
+
+-- | Like 'Control.Effect.Error.catchError', but delegating to
+-- 'Control.Exception.catch' under the hood, which allows catching
+-- errors that might occur when lifting 'IO' computations.
+-- Unhandled errors are rethrown. Use 'SomeException' if you want
+-- to catch all errors.
+catch :: (Member Catch sig, Carrier sig m, Exc.Exception e)
+        => m a
+        -> (e -> m a)
+        -> m a
+catch go cleanup = send (CatchIO go cleanup ret)
+
+runCatch :: (Carrier sig m, MonadIO m)
+         => (forall x . m x -> IO x)
+         -> Eff (CatchC m) a
+         -> m a
+runCatch handler = runCatchC handler . interpret
+
+newtype CatchC m a = CatchC ((forall x . m x -> IO x) -> m a)
+
+runCatchC :: (forall x . m x -> IO x) -> CatchC m a -> m a
+runCatchC handler (CatchC m) = m handler
+
+instance (Carrier sig m, MonadIO m) => Carrier (Catch :+: sig) (CatchC m) where
+  ret a = CatchC (const (ret a))
+  eff op = CatchC (\ handler -> handleSum
+    (eff . handlePure (runCatchC handler))
+    (\case
+        CatchIO go cleanup k -> liftIO (Exc.catch
+                                         (handler (runCatchC handler go))
+                                         (handler . runCatchC handler . cleanup))
+                                >>= runCatchC handler . k
+    ) op)
diff --git a/src/Semantic/Task.hs b/src/Semantic/Task.hs
index eae9d00cf..266667489 100644
--- a/src/Semantic/Task.hs
+++ b/src/Semantic/Task.hs
@@ -326,7 +326,7 @@ runParser blob@Blob{..} parser = case parser of
             writeLog Error "failed parsing" (("task", "parse") : blobFields)
             throwError (toException err)
 
-          res <- timeout (configAssignmentTimeout config) . time "parse.assign" languageTag $
+          time "parse.assign" languageTag $
             case assign blobSource assignment ast of
               Left err -> do
                 writeStat (increment "parse.assign_errors" languageTag)
@@ -343,9 +343,9 @@ runParser blob@Blob{..} parser = case parser of
                     logError config Warning blob err (("task", "assign") : blobFields)
                     when (optionsFailOnWarning (configOptions config)) $ throwError (toException err)
                 term <$ writeStat (count "parse.nodes" (length term) languageTag)
-          case res of
-            Just r -> pure r
-            Nothing -> do
-              writeStat (increment "assign.assign_timeouts" languageTag)
-              writeLog Error "assignment timeout" (("task", "assign") : blobFields)
-              throwError (SomeException AssignmentTimedOut)
+          -- case res of
+          --   Just r -> pure r
+          --   Nothing -> do
+          --     writeStat (increment "assign.assign_timeouts" languageTag)
+          --     writeLog Error "assignment timeout" (("task", "assign") : blobFields)
+          --     throwError (SomeException AssignmentTimedOut)