Remove Hoogle lock

src/Application.hs

@@ -160,7 +160,6 @@ withFoundation appLogFunc appSettings inner = do
                 \oldMatcher -> getLatestMatcher appHttpManager `catchAny` \e -> do
                   runRIO appLogFunc $ RIO.logError $ "Couldn't get Stack matcher: " <> displayShow e
                   pure oldMatcher
-        appHoogleLock <- newMVar ()
         appMirrorStatus <- mkUpdateMirrorStatus
         hoogleLocker <- newHoogleLocker appLogFunc appHttpManager
         let appGetHoogleDB = singleRun hoogleLocker

src/Foundation.hs

@@ -35,9 +35,6 @@ data App = App
     , appStackageDatabase   :: !StackageDatabase
     , appLatestStackMatcher :: !(IO (Text -> Maybe Text))
     -- ^ Give a pattern, get a URL
-    , appHoogleLock         :: !(MVar ())
-    -- ^ Avoid concurrent Hoogle queries, see
-    -- https://github.com/fpco/stackage-server/issues/172
     , appMirrorStatus       :: !(IO (Status, WidgetFor App ()))
     , appGetHoogleDB        :: !(SnapName -> IO (Maybe FilePath))
     , appGitRev             :: !GitRev

src/Handler/Hoogle.hs

@@ -47,9 +47,6 @@ getHoogleR name0 = track "Handler.Hoogle.getHoogleR" do
     mdatabasePath <- getHoogleDB name
     dbPath <- maybe (hoogleDatabaseNotAvailableFor name) return mdatabasePath
 
-    -- Avoid concurrent Hoogle queries, see
-    -- https://github.com/fpco/stackage-server/issues/172
-    lock <- appHoogleLock <$> getYesod
     urlRender <- getUrlRender
     HoogleQueryOutput results mtotalCount <-
       case mquery of
@@ -64,9 +61,7 @@ getHoogleR name0 = track "Handler.Hoogle.getHoogleR" do
                     , hqiExact = exact
                     }
 
-            liftIO $ withMVar lock
-                   $ const
-                   $ Hoogle.withDatabase dbPath
+            liftIO $ Hoogle.withDatabase dbPath
                    -- NB! I got a segfault when I didn't force with $!
                    $ \db -> return $! runHoogleQuery urlRender name db input
         Nothing -> return $ HoogleQueryOutput [] Nothing