From 3a271a488b6aa43ab72abf544bf53b43f99b63da Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 11 Dec 2021 22:56:22 +0000
Subject: [PATCH 1/2] lockless debouncer (#2469)

---
 ghcide/src/Development/IDE/Core/Debouncer.hs | 28 ++++++++++----------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Debouncer.hs b/ghcide/src/Development/IDE/Core/Debouncer.hs
index e65049501fb..f0785d56e9b 100644
--- a/ghcide/src/Development/IDE/Core/Debouncer.hs
+++ b/ghcide/src/Development/IDE/Core/Debouncer.hs
@@ -9,13 +9,13 @@ module Development.IDE.Core.Debouncer
     ) where
 
 import           Control.Concurrent.Async
-import           Control.Concurrent.Strict
+import           Control.Concurrent.STM.Stats (atomically, atomicallyNamed)
 import           Control.Exception
-import           Control.Monad             (join)
-import           Data.Foldable             (traverse_)
-import           Data.HashMap.Strict       (HashMap)
-import qualified Data.HashMap.Strict       as Map
+import           Control.Monad                (join)
+import           Data.Foldable                (traverse_)
 import           Data.Hashable
+import qualified Focus
+import qualified StmContainers.Map            as STM
 import           System.Time.Extra
 
 -- | A debouncer can be used to avoid triggering many events
@@ -31,7 +31,7 @@ newtype Debouncer k = Debouncer { registerEvent :: Seconds -> k -> IO () -> IO (
 
 -- | Debouncer used in the IDE that delays events as expected.
 newAsyncDebouncer :: (Eq k, Hashable k) => IO (Debouncer k)
-newAsyncDebouncer = Debouncer . asyncRegisterEvent <$> newVar Map.empty
+newAsyncDebouncer = Debouncer . asyncRegisterEvent <$> STM.newIO
 
 -- | Register an event that will fire after the given delay if no other event
 -- for the same key gets registered until then.
@@ -39,20 +39,20 @@ newAsyncDebouncer = Debouncer . asyncRegisterEvent <$> newVar Map.empty
 -- If there is a pending event for the same key, the pending event will be killed.
 -- Events are run unmasked so it is up to the user of `registerEvent`
 -- to mask if required.
-asyncRegisterEvent :: (Eq k, Hashable k) => Var (HashMap k (Async ())) -> Seconds -> k -> IO () -> IO ()
+asyncRegisterEvent :: (Eq k, Hashable k) => STM.Map k (Async ()) -> Seconds -> k -> IO () -> IO ()
 asyncRegisterEvent d 0 k fire = do
-    join $ modifyVar d $ \m -> do
-        (cancel, !m') <- evaluate $ Map.alterF (\prev -> (traverse_ cancel prev, Nothing)) k m
-        return (m', cancel)
+    join $ atomically $ do
+        prev <- STM.focus Focus.lookupAndDelete k d
+        return $ traverse_ cancel prev
     fire
 asyncRegisterEvent d delay k fire = mask_ $ do
     a <- asyncWithUnmask $ \unmask -> unmask $ do
         sleep delay
         fire
-        modifyVar_ d (evaluate . Map.delete k)
-    join $ modifyVar d $ \m -> do
-        (cancel, !m') <- evaluate $ Map.alterF (\prev -> (traverse_ cancel prev, Just a)) k m
-        return (m', cancel)
+        atomically $ STM.delete k d
+    do
+        prev <- atomicallyNamed "debouncer" $ STM.focus (Focus.lookup <* Focus.insert a) k d
+        traverse_ cancel prev
 
 -- | Debouncer used in the DAML CLI compiler that emits events immediately.
 noopDebouncer :: Debouncer k

From 57cf81e8e9cb9c69717e77b20cd27086cae8197c Mon Sep 17 00:00:00 2001
From: Jan Hrcek <2716069+jhrcek@users.noreply.github.com>
Date: Sun, 12 Dec 2021 09:49:19 +0100
Subject: [PATCH 2/2] Handle re-exported modules when constructing ExportsMap
 (#2468)

* Handle re-exported modules when constructing ExportsMap

* Remove unused import, use let

Co-authored-by: Pepe Iborra <pepeiborra@gmail.com>
---
 ghcide/src/Development/IDE/Types/HscEnvEq.hs | 22 +++++++++++---------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/ghcide/src/Development/IDE/Types/HscEnvEq.hs b/ghcide/src/Development/IDE/Types/HscEnvEq.hs
index 0383ffc59e3..d175bb884d3 100644
--- a/ghcide/src/Development/IDE/Types/HscEnvEq.hs
+++ b/ghcide/src/Development/IDE/Types/HscEnvEq.hs
@@ -16,7 +16,6 @@ import           Control.Concurrent.Strict       (modifyVar, newVar)
 import           Control.DeepSeq                 (force)
 import           Control.Exception               (evaluate, mask, throwIO)
 import           Control.Monad.Extra             (eitherM, join, mapMaybeM)
-import           Control.Monad.IO.Class
 import           Data.Either                     (fromRight)
 import           Data.Set                        (Set)
 import qualified Data.Set                        as Set
@@ -76,22 +75,25 @@ newHscEnvEqWithImportPaths envImportPaths hscEnv deps = do
         -- compute the package imports
         let pkgst   = unitState hscEnv
             depends = explicitUnits pkgst
-            targets =
-                [ (pkg, mn)
+            modules =
+                [ m
                 | d        <- depends
                 , Just pkg <- [lookupPackageConfig d hscEnv]
-                , (mn, _)  <- unitExposedModules pkg
+                , (modName, maybeOtherPkgMod) <- unitExposedModules pkg
+                , let m = case maybeOtherPkgMod of
+                        -- When module is re-exported from another package,
+                        -- the origin module is represented by value in Just
+                        Just otherPkgMod -> otherPkgMod
+                        Nothing -> mkModule (unitInfoId pkg) modName
                 ]
 
-            doOne (pkg, mn) = do
-                modIface <- liftIO $ initIfaceLoad hscEnv $ loadInterface
-                    ""
-                    (mkModule (unitInfoId pkg) mn)
-                    (ImportByUser NotBoot)
+            doOne m = do
+                modIface <- initIfaceLoad hscEnv $
+                    loadInterface "" m (ImportByUser NotBoot)
                 return $ case modIface of
                     Maybes.Failed    _r -> Nothing
                     Maybes.Succeeded mi -> Just mi
-        modIfaces <- mapMaybeM doOne targets
+        modIfaces <- mapMaybeM doOne modules
         return $ createExportsMap modIfaces
 
     -- similar to envPackageExports, evaluated lazily