From 088db2a62787257fbdd78c75143e1ab3d0177eb3 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Fri, 8 Oct 2021 19:45:42 +0100
Subject: [PATCH 01/15] Collect metrics and expose an EKG server

---
 cabal.project                              | 14 ++++++++
 docs/contributing/contributing.md          | 29 +++++++++++++++
 ghcide/ghcide.cabal                        |  2 ++
 ghcide/src/Development/IDE/Core/Service.hs |  7 ++--
 ghcide/src/Development/IDE/Core/Shake.hs   | 41 ++++++++++++++++++++--
 ghcide/src/Development/IDE/Main.hs         | 35 ++++++++++++++----
 6 files changed, 117 insertions(+), 11 deletions(-)

diff --git a/cabal.project b/cabal.project
index 78ceb8e2ff..122d60eaf1 100644
--- a/cabal.project
+++ b/cabal.project
@@ -53,6 +53,12 @@ constraints:
   ghc-lib-parser-ex -auto,
   stylish-haskell +ghc-lib
 
+ source-repository-package
+  type:git
+  location: https://github.com/vshabanov/ekg-json
+  tag: 00ebe7211c981686e65730b7144fbf5350462608
+  -- https://github.com/tibbe/ekg-json/pull/12
+
 allow-newer:
   -- ghc-9.2
   ----------
@@ -70,3 +76,11 @@ allow-newer:
   -- for shake-bench
   Chart:lens,
   Chart-diagrams:lens,
+
+  -- for ekg
+  ekg-core:base,
+  ekg-wai:base,
+
+  -- for shake-bench
+  Chart-diagrams:diagrams-core,
+  SVGFonts:diagrams-core
diff --git a/docs/contributing/contributing.md b/docs/contributing/contributing.md
index 2dde423b74..20762ccbd1 100644
--- a/docs/contributing/contributing.md
+++ b/docs/contributing/contributing.md
@@ -225,6 +225,35 @@ If you don't want to use [nix](https://nixos.org/guides/install-nix.html), you c
 
 See the [tutorial](./plugin-tutorial.md) on writing a plugin in HLS.
 
+## Measuring, benchmarking and tracing
+
+### Metrics
+
+HLS opens a metrics server on port 8000 exposing GC and ghcide metrics. The ghcide metrics currently exposed are:
+
+- `ghcide.values_count`- count of build results in the store
+- `ghcide.database_count` - count of build keys in the store (these two would be the same in the absence of GC)
+- `ghcide.build_count` - build count. A key is GC'ed if it is dirty and older than 100 builds
+- `ghcide.dirty_keys_count` - non transitive count of dirty build keys
+- `ghcide.indexing_pending_count` - count of items in the indexing queue
+- `ghcide.exports_map_count` - count of identifiers in the exports map.
+
+### Benchmarks
+
+If you are touching performance sensitive code, take the time to run a differential
+benchmark between HEAD and master using the benchHist script. This assumes that
+"master" points to the upstream master.
+
+Run the benchmarks with `cabal bench ghcide`.
+
+It should take around 25 minutes and the results will be stored in the `ghcide/bench-results` folder. To interpret the results, see the comments in the `ghcide/bench/hist/Main.hs` module.
+
+More details in [bench/README](../../ghcide/bench/README.md)
+
+### Tracing
+
+HLS records opentelemetry eventlog traces via [opentelemetry](https://hackage.haskell.org/package/opentelemetry). To generate the traces, build with `-eventlog` and run with `+RTS -l`. To visualize the traces, install [Tracy](https://github.com/wolfpld/tracy) and use [eventlog-to-tracy](https://hackage.haskell.org/package/opentelemetry-extra) to open the generated eventlog.
+
 ## Adding support for a new editor
 
 Adding support for new editors is fairly easy if the editor already has good support for generic LSP-based extensions.
diff --git a/ghcide/ghcide.cabal b/ghcide/ghcide.cabal
index 93bd51a950..acf6e068ad 100644
--- a/ghcide/ghcide.cabal
+++ b/ghcide/ghcide.cabal
@@ -48,6 +48,8 @@ library
         dependent-map,
         dependent-sum,
         dlist,
+        ekg-wai,
+        ekg-core,
         exceptions,
         extra >= 1.7.4,
         enummapset,
diff --git a/ghcide/src/Development/IDE/Core/Service.hs b/ghcide/src/Development/IDE/Core/Service.hs
index 0dd04a2cd7..efca483663 100644
--- a/ghcide/src/Development/IDE/Core/Service.hs
+++ b/ghcide/src/Development/IDE/Core/Service.hs
@@ -38,10 +38,11 @@ import           Control.Monad
 import qualified Development.IDE.Core.FileExists as FileExists
 import qualified Development.IDE.Core.OfInterest as OfInterest
 import           Development.IDE.Core.Shake      hiding (Log)
+import           Development.IDE.Core.Shake
 import qualified Development.IDE.Core.Shake      as Shake
 import           Development.IDE.Types.Shake     (WithHieDb)
 import           System.Environment              (lookupEnv)
-
+import           System.Metrics
 
 data Log
   = LogShake Shake.Log
@@ -68,8 +69,9 @@ initialise :: Recorder (WithPriority Log)
            -> IdeOptions
            -> WithHieDb
            -> IndexQueue
+           -> Maybe Store
            -> IO IdeState
-initialise recorder defaultConfig mainRule lspEnv logger debouncer options withHieDb hiedbChan = do
+initialise recorder defaultConfig mainRule lspEnv logger debouncer options withHieDb hiedbChan metrics = do
     shakeProfiling <- do
         let fromConf = optShakeProfiling options
         fromEnv <- lookupEnv "GHCIDE_BUILD_PROFILING"
@@ -86,6 +88,7 @@ initialise recorder defaultConfig mainRule lspEnv logger debouncer options withH
         withHieDb
         hiedbChan
         (optShakeOptions options)
+        metrics
           $ do
             addIdeGlobal $ GlobalIdeOptions options
             ofInterestRules (cmapWithPrio LogOfInterest recorder)
diff --git a/ghcide/src/Development/IDE/Core/Shake.hs b/ghcide/src/Development/IDE/Core/Shake.hs
index 808de1d1a6..28e3ab2ff5 100644
--- a/ghcide/src/Development/IDE/Core/Shake.hs
+++ b/ghcide/src/Development/IDE/Core/Shake.hs
@@ -136,6 +136,7 @@ import           Development.IDE.Graph                  hiding (ShakeValue)
 import qualified Development.IDE.Graph                  as Shake
 import           Development.IDE.Graph.Database         (ShakeDatabase,
                                                          shakeGetBuildStep,
+                                                         shakeGetDatabaseKeys,
                                                          shakeNewDatabase,
                                                          shakeProfileDatabase,
                                                          shakeRunDatabaseForKeys)
@@ -152,6 +153,23 @@ import           Development.IDE.Types.Options
 import           Development.IDE.Types.Shake
 import qualified Focus
 import           GHC.Fingerprint
+import           Language.LSP.Types.Capabilities
+import           OpenTelemetry.Eventlog
+
+import           Control.Exception.Extra                hiding (bracket_)
+import           Data.Aeson                             (toJSON)
+import qualified Data.ByteString.Char8                  as BS8
+import           Data.Coerce                            (coerce)
+import           Data.Default
+import           Data.Foldable                          (for_, toList)
+import           Data.HashSet                           (HashSet)
+import qualified Data.HashSet                           as HSet
+import           Data.IORef.Extra                       (atomicModifyIORef'_,
+                                                         atomicModifyIORef_)
+import           Data.String                            (fromString)
+import           Data.Text                              (pack)
+import           Debug.Trace.Flags                      (userTracingEnabled)
+import qualified Development.IDE.Types.Exports          as ExportsMap
 import           HieDb.Types
 import           Ide.Plugin.Config
 import qualified Ide.PluginUtils                        as HLS
@@ -167,6 +185,7 @@ import           OpenTelemetry.Eventlog
 import qualified StmContainers.Map                      as STM
 import           System.FilePath                        hiding (makeRelative)
 import           System.IO.Unsafe (unsafePerformIO)
+import           System.Metrics                         (Store, registerCounter, registerGauge)
 import           System.Time.Extra
 
 data Log
@@ -388,7 +407,7 @@ lastValueIO s@ShakeExtras{positionMapping,persistentKeys,state} k file = do
           | otherwise = do
           pmap <- readTVarIO persistentKeys
           mv <- runMaybeT $ do
-            liftIO $ Logger.logDebug (logger s) $ T.pack $ "LOOKUP UP PERSISTENT FOR: " ++ show k
+            liftIO $ Logger.logDebug (logger s) $ T.pack $ "LOOKUP PERSISTENT FOR: " ++ show k
             f <- MaybeT $ pure $ HMap.lookup (Key k) pmap
             (dv,del,ver) <- MaybeT $ runIdeAction "lastValueIO" s $ f file
             MaybeT $ pure $ (,del,ver) <$> fromDynamic dv
@@ -557,10 +576,11 @@ shakeOpen :: Recorder (WithPriority Log)
           -> WithHieDb
           -> IndexQueue
           -> ShakeOptions
+          -> Maybe Store
           -> Rules ()
           -> IO IdeState
 shakeOpen recorder lspEnv defaultConfig logger debouncer
-  shakeProfileDir (IdeReportProgress reportProgress) ideTesting@(IdeTesting testing) withHieDb indexQueue opts rules = mdo
+  shakeProfileDir (IdeReportProgress reportProgress) ideTesting@(IdeTesting testing) withHieDb indexQueue opts metrics rules = mdo
     let log :: Logger.Priority -> Log -> IO ()
         log = logWith recorder
 
@@ -613,11 +633,28 @@ shakeOpen recorder lspEnv defaultConfig logger debouncer
     IdeOptions
         { optOTMemoryProfiling = IdeOTMemoryProfiling otProfilingEnabled
         , optProgressStyle
+        , optCheckParents
         } <- getIdeOptionsIO shakeExtras
 
     void $ startTelemetry shakeDb shakeExtras
     startProfilingTelemetry otProfilingEnabled logger $ state shakeExtras
 
+    checkParents <- optCheckParents
+    for_ metrics $ \store -> do
+        let readValuesCounter = fromIntegral . countRelevantKeys checkParents . HMap.keys <$> readVar (state shakeExtras)
+            readDirtyKeys = fromIntegral . countRelevantKeys checkParents . HSet.toList <$> readIORef (dirtyKeys shakeExtras)
+            readIndexPending = fromIntegral . HMap.size <$> readTVarIO (indexPending $ hiedbWriter shakeExtras)
+            readExportsMap = fromIntegral . HMap.size . getExportsMap <$> readVar (exportsMap shakeExtras)
+            readDatabaseCount = fromIntegral . countRelevantKeys checkParents . map fst <$> shakeGetDatabaseKeys shakeDb
+            readDatabaseStep =  fromIntegral <$> shakeGetBuildStep shakeDb
+
+        registerGauge "ghcide.values_count" readValuesCounter store
+        registerGauge "ghcide.dirty_keys_count" readDirtyKeys store
+        registerGauge "ghcide.indexing_pending_count" readIndexPending store
+        registerGauge "ghcide.exports_map_count" readExportsMap store
+        registerGauge "ghcide.database_count" readDatabaseCount store
+        registerCounter "ghcide.num_builds" readDatabaseStep store
+
     return ideState
 
 startTelemetry :: ShakeDatabase -> ShakeExtras -> IO (Async ())
diff --git a/ghcide/src/Development/IDE/Main.hs b/ghcide/src/Development/IDE/Main.hs
index 43e9827c8b..55c411887d 100644
--- a/ghcide/src/Development/IDE/Main.hs
+++ b/ghcide/src/Development/IDE/Main.hs
@@ -29,6 +29,7 @@ import           Data.Maybe                            (catMaybes, isJust)
 import qualified Data.Text                             as T
 import           Data.Text.Lazy.Encoding               (decodeUtf8)
 import qualified Data.Text.Lazy.IO                     as LT
+import           Data.Traversable                      (for)
 import           Data.Typeable                         (typeOf)
 import           Development.IDE                       (Action, GhcVersion (..),
                                                         Priority (Debug, Error), Rules,
@@ -126,6 +127,9 @@ import           System.IO                             (BufferMode (LineBufferin
                                                         hSetEncoding, stderr,
                                                         stdin, stdout, utf8)
 import           System.Random                         (newStdGen)
+import qualified System.Metrics                        as Monitoring
+import           System.Remote.Monitoring.Wai
+import qualified System.Remote.Monitoring.Wai          as Monitoring
 import           System.Time.Extra                     (Seconds, offsetTime,
                                                         showDuration)
 import           Text.Printf                           (printf)
@@ -231,6 +235,7 @@ data Arguments = Arguments
     , argsHandleIn              :: IO Handle
     , argsHandleOut             :: IO Handle
     , argsThreads               :: Maybe Natural
+    , argsMonitoringPort        :: Maybe Natural
     }
 
 
@@ -268,6 +273,7 @@ defaultArguments recorder logger = Arguments
                 -- the language server tests without the redirection.
                 putStr " " >> hFlush stdout
                 return newStdout
+        , argsMonitoringPort = Just 8000
         }
 
 
@@ -355,6 +361,23 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                 -- FIXME: Remove this after GHC 9 gets fully supported
                 when (ghcVersion == GHC90) $
                     log Warning LogOnlyPartialGhc9Support
+                server <- fmap join $ for argsMonitoringPort $ \p -> do
+                    store <- Monitoring.newStore
+                    let startServer = Monitoring.forkServerWith store "localhost" (fromIntegral p)
+                    -- this can fail if the port is busy, throwing an async exception back to us
+                    -- to handle that, wrap the server thread in an async
+                    mb_server <- async startServer >>= waitCatch
+                    case mb_server of
+                        Right s -> do
+                            logInfo logger $ T.pack $
+                                "Started monitoring server on port " <> show p
+                            return $ Just s
+                        Left e -> do
+                            logInfo logger $ T.pack $
+                                "Unable to bind monitoring server on port "
+                                <> show p <> ":" <> show e
+                            return Nothing
+
                 initialise
                     (cmapWithPrio LogService recorder)
                     argsDefaultHlsConfig
@@ -365,6 +388,9 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                     options
                     withHieDb
                     hieChan
+                    (Monitoring.serverMetricStore <$> server)
+                    `onException`
+                        traverse_ (killThread . serverThreadId) server
             dumpSTMStats
         Check argFiles -> do
           dir <- maybe IO.getCurrentDirectory return argsProjectRoot
@@ -397,7 +423,7 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                         , optCheckProject = pure False
                         , optModifyDynFlags = optModifyDynFlags def_options <> pluginModifyDynflags plugins
                         }
-            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan
+            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan Nothing
             shakeSessionInit (cmapWithPrio LogShake recorder) ide
             registerIdeConfiguration (shakeExtras ide) $ IdeConfiguration mempty (hashed Nothing)
 
@@ -450,13 +476,8 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                     , optCheckProject = pure False
                     , optModifyDynFlags = optModifyDynFlags def_options <> pluginModifyDynflags plugins
                     }
-            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan
+            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan Nothing
             shakeSessionInit (cmapWithPrio LogShake recorder) ide
-            registerIdeConfiguration (shakeExtras ide) $ IdeConfiguration mempty (hashed Nothing)
-            c ide
-
-{-# ANN defaultMain ("HLint: ignore Use nubOrd" :: String) #-}
-
 
 expandFiles :: [FilePath] -> IO [FilePath]
 expandFiles = concatMapM $ \x -> do

From ad1fb0d37fe0b877aae9ad9bd92df5be378db92d Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 12 Oct 2021 20:23:44 +0100
Subject: [PATCH 02/15] register gc metrics locally

---
 ghcide/src/Development/IDE/Main.hs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ghcide/src/Development/IDE/Main.hs b/ghcide/src/Development/IDE/Main.hs
index 55c411887d..7ea8b82f85 100644
--- a/ghcide/src/Development/IDE/Main.hs
+++ b/ghcide/src/Development/IDE/Main.hs
@@ -363,6 +363,7 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                     log Warning LogOnlyPartialGhc9Support
                 server <- fmap join $ for argsMonitoringPort $ \p -> do
                     store <- Monitoring.newStore
+                    Monitoring.registerGcMetrics store
                     let startServer = Monitoring.forkServerWith store "localhost" (fromIntegral p)
                     -- this can fail if the port is busy, throwing an async exception back to us
                     -- to handle that, wrap the server thread in an async

From 816043c0de0cd5a2a416379d1c3eaf667021b63b Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 30 Apr 2022 08:07:27 +0100
Subject: [PATCH 03/15] getDatabaseKeys

---
 hls-graph/src/Development/IDE/Graph/Database.hs          | 6 ++++++
 hls-graph/src/Development/IDE/Graph/Internal/Database.hs | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/hls-graph/src/Development/IDE/Graph/Database.hs b/hls-graph/src/Development/IDE/Graph/Database.hs
index 53406bc3dd..1d5aab3789 100644
--- a/hls-graph/src/Development/IDE/Graph/Database.hs
+++ b/hls-graph/src/Development/IDE/Graph/Database.hs
@@ -9,6 +9,7 @@ module Development.IDE.Graph.Database(
     shakeRunDatabaseForKeys,
     shakeProfileDatabase,
     shakeGetBuildStep,
+    shakeGetDatabaseKeys,
     shakeGetDirtySet,
     shakeGetCleanKeys
     ,shakeGetBuildEdges) where
@@ -79,3 +80,8 @@ shakeGetBuildEdges (ShakeDatabase _ _ db) = do
     keys <- getDatabaseValues db
     let ress = mapMaybe (getResult . snd) keys
     return $ sum $ map (length . getResultDepsDefault [] . resultDeps) ress
+
+-- | Returns an approximation of the database keys,
+--   annotated with how long ago (in # builds) they were visited
+shakeGetDatabaseKeys :: ShakeDatabase -> IO [(Key, Int)]
+shakeGetDatabaseKeys (ShakeDatabase _ _ db) = getKeysAndVisitAge db
diff --git a/hls-graph/src/Development/IDE/Graph/Internal/Database.hs b/hls-graph/src/Development/IDE/Graph/Internal/Database.hs
index a6282a05eb..0ed2ccbb64 100644
--- a/hls-graph/src/Development/IDE/Graph/Internal/Database.hs
+++ b/hls-graph/src/Development/IDE/Graph/Internal/Database.hs
@@ -199,7 +199,7 @@ getDirtySet db = do
         calcAgeStatus _         = Nothing
     return $ mapMaybe (secondM calcAgeStatus) dbContents
 
--- | Returns ann approximation of the database keys,
+-- | Returns an approximation of the database keys,
 --   annotated with how long ago (in # builds) they were visited
 getKeysAndVisitAge :: Database -> IO [(Key, Int)]
 getKeysAndVisitAge db = do

From ab13cfe81e24005cde195bb6332953cf65746bcf Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 30 Apr 2022 08:17:58 +0100
Subject: [PATCH 04/15] fixups

---
 ghcide/src/Development/IDE/Core/Service.hs |  1 -
 ghcide/src/Development/IDE/Core/Shake.hs   | 27 +++++-----------------
 ghcide/src/Development/IDE/Main.hs         | 13 +++++++----
 3 files changed, 15 insertions(+), 26 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Service.hs b/ghcide/src/Development/IDE/Core/Service.hs
index efca483663..28183651f9 100644
--- a/ghcide/src/Development/IDE/Core/Service.hs
+++ b/ghcide/src/Development/IDE/Core/Service.hs
@@ -38,7 +38,6 @@ import           Control.Monad
 import qualified Development.IDE.Core.FileExists as FileExists
 import qualified Development.IDE.Core.OfInterest as OfInterest
 import           Development.IDE.Core.Shake      hiding (Log)
-import           Development.IDE.Core.Shake
 import qualified Development.IDE.Core.Shake      as Shake
 import           Development.IDE.Types.Shake     (WithHieDb)
 import           System.Environment              (lookupEnv)
diff --git a/ghcide/src/Development/IDE/Core/Shake.hs b/ghcide/src/Development/IDE/Core/Shake.hs
index 28e3ab2ff5..a461d82bc1 100644
--- a/ghcide/src/Development/IDE/Core/Shake.hs
+++ b/ghcide/src/Development/IDE/Core/Shake.hs
@@ -155,21 +155,6 @@ import qualified Focus
 import           GHC.Fingerprint
 import           Language.LSP.Types.Capabilities
 import           OpenTelemetry.Eventlog
-
-import           Control.Exception.Extra                hiding (bracket_)
-import           Data.Aeson                             (toJSON)
-import qualified Data.ByteString.Char8                  as BS8
-import           Data.Coerce                            (coerce)
-import           Data.Default
-import           Data.Foldable                          (for_, toList)
-import           Data.HashSet                           (HashSet)
-import qualified Data.HashSet                           as HSet
-import           Data.IORef.Extra                       (atomicModifyIORef'_,
-                                                         atomicModifyIORef_)
-import           Data.String                            (fromString)
-import           Data.Text                              (pack)
-import           Debug.Trace.Flags                      (userTracingEnabled)
-import qualified Development.IDE.Types.Exports          as ExportsMap
 import           HieDb.Types
 import           Ide.Plugin.Config
 import qualified Ide.PluginUtils                        as HLS
@@ -178,10 +163,8 @@ import           Language.LSP.Diagnostics
 import qualified Language.LSP.Server                    as LSP
 import           Language.LSP.Types
 import qualified Language.LSP.Types                     as LSP
-import           Language.LSP.Types.Capabilities
 import           Language.LSP.VFS
 import qualified "list-t" ListT
-import           OpenTelemetry.Eventlog
 import qualified StmContainers.Map                      as STM
 import           System.FilePath                        hiding (makeRelative)
 import           System.IO.Unsafe (unsafePerformIO)
@@ -641,10 +624,10 @@ shakeOpen recorder lspEnv defaultConfig logger debouncer
 
     checkParents <- optCheckParents
     for_ metrics $ \store -> do
-        let readValuesCounter = fromIntegral . countRelevantKeys checkParents . HMap.keys <$> readVar (state shakeExtras)
-            readDirtyKeys = fromIntegral . countRelevantKeys checkParents . HSet.toList <$> readIORef (dirtyKeys shakeExtras)
+        let readValuesCounter = fromIntegral . countRelevantKeys checkParents <$> getStateKeys shakeExtras
+            readDirtyKeys = fromIntegral . countRelevantKeys checkParents . HSet.toList <$> readTVarIO(dirtyKeys shakeExtras)
             readIndexPending = fromIntegral . HMap.size <$> readTVarIO (indexPending $ hiedbWriter shakeExtras)
-            readExportsMap = fromIntegral . HMap.size . getExportsMap <$> readVar (exportsMap shakeExtras)
+            readExportsMap = fromIntegral . HMap.size . getExportsMap <$> readTVarIO (exportsMap shakeExtras)
             readDatabaseCount = fromIntegral . countRelevantKeys checkParents . map fst <$> shakeGetDatabaseKeys shakeDb
             readDatabaseStep =  fromIntegral <$> shakeGetBuildStep shakeDb
 
@@ -666,7 +649,7 @@ startTelemetry db extras@ShakeExtras{..}
     IdeOptions{optCheckParents} <- getIdeOptionsIO extras
     checkParents <- optCheckParents
     regularly 1 $ do
-        observe countKeys . countRelevantKeys checkParents . map fst =<< (atomically . ListT.toList . STM.listT) state
+        observe countKeys . countRelevantKeys checkParents =<< getStateKeys extras
         readTVarIO dirtyKeys >>= observe countDirty . countRelevantKeys checkParents . HSet.toList
         shakeGetBuildStep db >>= observe countBuilds
 
@@ -675,6 +658,8 @@ startTelemetry db extras@ShakeExtras{..}
         regularly :: Seconds -> IO () -> IO (Async ())
         regularly delay act = async $ forever (act >> sleep delay)
 
+getStateKeys :: ShakeExtras -> IO [Key]
+getStateKeys = (fmap.fmap) fst . atomically . ListT.toList . STM.listT . state
 
 -- | Must be called in the 'Initialized' handler and only once
 shakeSessionInit :: Recorder (WithPriority Log) -> IdeState -> IO ()
diff --git a/ghcide/src/Development/IDE/Main.hs b/ghcide/src/Development/IDE/Main.hs
index 7ea8b82f85..1180b00afc 100644
--- a/ghcide/src/Development/IDE/Main.hs
+++ b/ghcide/src/Development/IDE/Main.hs
@@ -11,12 +11,14 @@ module Development.IDE.Main
 ,testing
 ,Log(..)
 ) where
-import           Control.Concurrent.Extra              (withNumCapabilities)
+import           Control.Concurrent.Async              (async, waitCatch)
+import           Control.Concurrent.Extra              (killThread, withNumCapabilities)
 import           Control.Concurrent.STM.Stats          (atomically,
                                                         dumpSTMStats)
 import           Control.Exception.Safe                (SomeException, catchAny,
-                                                        displayException)
-import           Control.Monad.Extra                   (concatMapM, unless,
+                                                        displayException,
+                                                        onException)
+import           Control.Monad.Extra                   (concatMapM, join, unless,
                                                         when)
 import qualified Data.Aeson.Encode.Pretty              as A
 import           Data.Default                          (Default (def))
@@ -34,7 +36,8 @@ import           Data.Typeable                         (typeOf)
 import           Development.IDE                       (Action, GhcVersion (..),
                                                         Priority (Debug, Error), Rules,
                                                         ghcVersion,
-                                                        hDuplicateTo')
+                                                        hDuplicateTo',
+                                                        logInfo)
 import           Development.IDE.Core.Debouncer        (Debouncer,
                                                         newAsyncDebouncer)
 import           Development.IDE.Core.FileStore        (isWatchSupported)
@@ -479,6 +482,8 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                     }
             ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan Nothing
             shakeSessionInit (cmapWithPrio LogShake recorder) ide
+            registerIdeConfiguration (shakeExtras ide) $ IdeConfiguration mempty (hashed Nothing)
+            c ide
 
 expandFiles :: [FilePath] -> IO [FilePath]
 expandFiles = concatMapM $ \x -> do

From c6319d396bf6375c7651d3ff383ad28ff76a4412 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 30 Apr 2022 12:04:51 +0100
Subject: [PATCH 05/15] Abstract monitoring and put EKG behind a Cabal flag

---
 docs/contributing/contributing.md             |  2 +-
 ghcide/exe/Arguments.hs                       |  7 +++
 ghcide/exe/Main.hs                            | 13 +++-
 ghcide/ghcide.cabal                           | 22 ++++++-
 ghcide/src/Development/IDE/Core/Service.hs    | 40 ++++++------
 ghcide/src/Development/IDE/Core/Shake.hs      | 62 ++++++++-----------
 ghcide/src/Development/IDE/Main.hs            | 57 ++++++-----------
 ghcide/src/Development/IDE/Monitoring/EKG.hs  | 34 ++++++++++
 .../IDE/Monitoring/OpenTelemetry.hs           | 31 ++++++++++
 .../src/Development/IDE/Types/Monitoring.hs   | 30 +++++++++
 10 files changed, 200 insertions(+), 98 deletions(-)
 create mode 100644 ghcide/src/Development/IDE/Monitoring/EKG.hs
 create mode 100644 ghcide/src/Development/IDE/Monitoring/OpenTelemetry.hs
 create mode 100644 ghcide/src/Development/IDE/Types/Monitoring.hs

diff --git a/docs/contributing/contributing.md b/docs/contributing/contributing.md
index 20762ccbd1..b885aa12c6 100644
--- a/docs/contributing/contributing.md
+++ b/docs/contributing/contributing.md
@@ -229,7 +229,7 @@ See the [tutorial](./plugin-tutorial.md) on writing a plugin in HLS.
 
 ### Metrics
 
-HLS opens a metrics server on port 8000 exposing GC and ghcide metrics. The ghcide metrics currently exposed are:
+When ghcide is built with the `ekg` flag, HLS opens a metrics server on port 8999 exposing GC and ghcide metrics. The ghcide metrics currently exposed are:
 
 - `ghcide.values_count`- count of build results in the store
 - `ghcide.database_count` - count of build keys in the store (these two would be the same in the absence of GC)
diff --git a/ghcide/exe/Arguments.hs b/ghcide/exe/Arguments.hs
index 4b5e8ae0fa..5a9c443bc6 100644
--- a/ghcide/exe/Arguments.hs
+++ b/ghcide/exe/Arguments.hs
@@ -1,6 +1,7 @@
 -- Copyright (c) 2019 The DAML Authors. All rights reserved.
 -- SPDX-License-Identifier: Apache-2.0
 
+{-# LANGUAGE CPP #-}
 module Arguments(Arguments(..), getArguments) where
 
 import           Development.IDE      (IdeState)
@@ -19,6 +20,9 @@ data Arguments = Arguments
     ,argsVerbose                    :: Bool
     ,argsCommand                    :: Command
     ,argsConservativeChangeTracking :: Bool
+#ifdef MONITORING_EKG
+    ,argsMonitoringPort             :: Int
+#endif
     }
 
 getArguments :: IdePlugins IdeState -> IO Arguments
@@ -40,6 +44,9 @@ arguments plugins = Arguments
       <*> switch (short 'd' <> long "verbose" <> help "Include internal events in logging output")
       <*> (commandP plugins <|> lspCommand <|> checkCommand)
       <*> switch (long "conservative-change-tracking" <> help "disable reactive change tracking (for testing/debugging)")
+#ifdef MONITORING_EKG
+      <*> option auto (long "monitoring-port" <> metavar "PORT" <> value 8999 <> showDefault <> help "Port to use for monitoring")
+#endif
       where
           checkCommand = Check <$> many (argument str (metavar "FILES/DIRS..."))
           lspCommand = LSP <$ flag' True (long "lsp" <> help "Start talking to an LSP client")
diff --git a/ghcide/exe/Main.hs b/ghcide/exe/Main.hs
index 37bab4d72e..ff7e554b5a 100644
--- a/ghcide/exe/Main.hs
+++ b/ghcide/exe/Main.hs
@@ -1,6 +1,7 @@
 -- Copyright (c) 2019 The DAML Authors. All rights reserved.
 -- SPDX-License-Identifier: Apache-2.0
 {-# OPTIONS_GHC -Wno-dodgy-imports #-} -- GHC no longer exports def in GHC 8.6 and above
+{-# LANGUAGE CPP             #-}
 {-# LANGUAGE TemplateHaskell #-}
 
 module Main(main) where
@@ -24,7 +25,6 @@ import           Development.IDE.Types.Logger      (Logger (Logger),
                                                     LoggingColumn (DataColumn, PriorityColumn),
                                                     Pretty (pretty),
                                                     Priority (Debug, Info, Error),
-                                                    Recorder (Recorder),
                                                     WithPriority (WithPriority, priority),
                                                     cfilter, cmapWithPrio,
                                                     makeDefaultStderrRecorder, layoutPretty, renderStrict, defaultLayoutOptions)
@@ -43,6 +43,11 @@ import           System.Exit                       (exitSuccess)
 import           System.IO                         (hPutStrLn, stderr)
 import           System.Info                       (compilerVersion)
 
+#ifdef MONITORING_EKG
+import qualified Development.IDE.Monitoring.OpenTelemetry as OpenTelemetry
+import qualified Development.IDE.Monitoring.EKG as EKG
+#endif
+
 data Log
   = LogIDEMain IDEMain.Log
   | LogRules Rules.Log
@@ -142,4 +147,10 @@ main = withTelemetryLogger $ \telemetryLogger -> do
                 , optCheckProject = pure $ checkProject config
                 , optRunSubset = not argsConservativeChangeTracking
                 }
+#ifdef MONITORING_EKG
+        , IDEMain.argsMonitoring = OpenTelemetry.monitoring <> EKG.monitoring logger argsMonitoringPort
+#ifdef MONITORING_EKG
+#endif
+#endif
+
         }
diff --git a/ghcide/ghcide.cabal b/ghcide/ghcide.cabal
index acf6e068ad..4a6109bcc9 100644
--- a/ghcide/ghcide.cabal
+++ b/ghcide/ghcide.cabal
@@ -30,6 +30,11 @@ flag ghc-patched-unboxed-bytecode
     default:     False
     manual:      True
 
+flag ekg
+    description: Enable EKG monitoring of the build graph and other metrics on port 8999
+    default:     False
+    manual:      True
+
 library
     default-language:   Haskell2010
     build-depends:
@@ -48,8 +53,6 @@ library
         dependent-map,
         dependent-sum,
         dlist,
-        ekg-wai,
-        ekg-core,
         exceptions,
         extra >= 1.7.4,
         enummapset,
@@ -200,6 +203,8 @@ library
         Development.IDE.Types.KnownTargets
         Development.IDE.Types.Location
         Development.IDE.Types.Logger
+        Development.IDE.Types.Monitoring
+        Development.IDE.Monitoring.OpenTelemetry
         Development.IDE.Types.Options
         Development.IDE.Types.Shake
         Development.IDE.Plugin
@@ -238,6 +243,14 @@ library
       exposed-modules:
         Development.IDE.GHC.Compat.CPP
 
+    if flag(ekg)
+        build-depends:
+            ekg-wai,
+            ekg-core,
+        cpp-options:   -DMONITORING_EKG
+        exposed-modules:
+            Development.IDE.Monitoring.EKG
+
 flag test-exe
     description: Build the ghcide-test-preprocessor executable
     default: True
@@ -358,6 +371,11 @@ executable ghcide
 
     if !flag(executable)
         buildable: False
+    if flag(ekg)
+        build-depends:
+            ekg-wai,
+            ekg-core,
+        cpp-options:   -DMONITORING_EKG
 
 test-suite ghcide-tests
     type: exitcode-stdio-1.0
diff --git a/ghcide/src/Development/IDE/Core/Service.hs b/ghcide/src/Development/IDE/Core/Service.hs
index 28183651f9..8ef090e84e 100644
--- a/ghcide/src/Development/IDE/Core/Service.hs
+++ b/ghcide/src/Development/IDE/Core/Service.hs
@@ -18,30 +18,30 @@ module Development.IDE.Core.Service(
     Log(..),
     ) where
 
-import           Control.Applicative             ((<|>))
+import           Control.Applicative              ((<|>))
 import           Development.IDE.Core.Debouncer
-import           Development.IDE.Core.FileExists (fileExistsRules)
-import           Development.IDE.Core.OfInterest hiding (Log, LogShake)
+import           Development.IDE.Core.FileExists  (fileExistsRules)
+import           Development.IDE.Core.OfInterest  hiding (Log, LogShake)
 import           Development.IDE.Graph
-import           Development.IDE.Types.Logger    as Logger (Logger,
-                                                            Pretty (pretty),
-                                                            Priority (Debug),
-                                                            Recorder,
-                                                            WithPriority,
-                                                            cmapWithPrio)
-import           Development.IDE.Types.Options   (IdeOptions (..))
+import           Development.IDE.Types.Logger     as Logger (Logger,
+                                                             Pretty (pretty),
+                                                             Priority (Debug),
+                                                             Recorder,
+                                                             WithPriority,
+                                                             cmapWithPrio)
+import           Development.IDE.Types.Options    (IdeOptions (..))
 import           Ide.Plugin.Config
-import qualified Language.LSP.Server             as LSP
-import qualified Language.LSP.Types              as LSP
+import qualified Language.LSP.Server              as LSP
+import qualified Language.LSP.Types               as LSP
 
 import           Control.Monad
-import qualified Development.IDE.Core.FileExists as FileExists
-import qualified Development.IDE.Core.OfInterest as OfInterest
-import           Development.IDE.Core.Shake      hiding (Log)
-import qualified Development.IDE.Core.Shake      as Shake
-import           Development.IDE.Types.Shake     (WithHieDb)
-import           System.Environment              (lookupEnv)
-import           System.Metrics
+import qualified Development.IDE.Core.FileExists  as FileExists
+import qualified Development.IDE.Core.OfInterest  as OfInterest
+import           Development.IDE.Core.Shake       hiding (Log)
+import qualified Development.IDE.Core.Shake       as Shake
+import           Development.IDE.Types.Monitoring (Monitoring)
+import           Development.IDE.Types.Shake      (WithHieDb)
+import           System.Environment               (lookupEnv)
 
 data Log
   = LogShake Shake.Log
@@ -68,7 +68,7 @@ initialise :: Recorder (WithPriority Log)
            -> IdeOptions
            -> WithHieDb
            -> IndexQueue
-           -> Maybe Store
+           -> Monitoring
            -> IO IdeState
 initialise recorder defaultConfig mainRule lspEnv logger debouncer options withHieDb hiedbChan metrics = do
     shakeProfiling <- do
diff --git a/ghcide/src/Development/IDE/Core/Shake.hs b/ghcide/src/Development/IDE/Core/Shake.hs
index a461d82bc1..fbd7c3795f 100644
--- a/ghcide/src/Development/IDE/Core/Shake.hs
+++ b/ghcide/src/Development/IDE/Core/Shake.hs
@@ -118,7 +118,6 @@ import           Data.Typeable
 import           Data.Unique
 import           Data.Vector                            (Vector)
 import qualified Data.Vector                            as Vector
-import           Debug.Trace.Flags                      (userTracingEnabled)
 import           Development.IDE.Core.Debouncer
 import           Development.IDE.Core.FileUtils         (getModTime)
 import           Development.IDE.Core.PositionMapping
@@ -168,8 +167,8 @@ import qualified "list-t" ListT
 import qualified StmContainers.Map                      as STM
 import           System.FilePath                        hiding (makeRelative)
 import           System.IO.Unsafe (unsafePerformIO)
-import           System.Metrics                         (Store, registerCounter, registerGauge)
 import           System.Time.Extra
+import Development.IDE.Types.Monitoring (Monitoring(..))
 
 data Log
   = LogCreateHieDbExportsMapStart
@@ -464,6 +463,7 @@ data IdeState = IdeState
     ,shakeSession         :: MVar ShakeSession
     ,shakeExtras          :: ShakeExtras
     ,shakeDatabaseProfile :: ShakeDatabase -> IO (Maybe FilePath)
+    ,stopMonitoring       :: IO ()
     }
 
 
@@ -559,11 +559,13 @@ shakeOpen :: Recorder (WithPriority Log)
           -> WithHieDb
           -> IndexQueue
           -> ShakeOptions
-          -> Maybe Store
+          -> Monitoring
           -> Rules ()
           -> IO IdeState
 shakeOpen recorder lspEnv defaultConfig logger debouncer
-  shakeProfileDir (IdeReportProgress reportProgress) ideTesting@(IdeTesting testing) withHieDb indexQueue opts metrics rules = mdo
+  shakeProfileDir (IdeReportProgress reportProgress)
+  ideTesting@(IdeTesting testing)
+  withHieDb indexQueue opts monitoring rules = mdo
     let log :: Logger.Priority -> Log -> IO ()
         log = logWith recorder
 
@@ -611,7 +613,6 @@ shakeOpen recorder lspEnv defaultConfig logger debouncer
             rules
     shakeSession <- newEmptyMVar
     shakeDatabaseProfile <- shakeDatabaseProfileIO shakeProfileDir
-    let ideState = IdeState{..}
 
     IdeOptions
         { optOTMemoryProfiling = IdeOTMemoryProfiling otProfilingEnabled
@@ -619,44 +620,30 @@ shakeOpen recorder lspEnv defaultConfig logger debouncer
         , optCheckParents
         } <- getIdeOptionsIO shakeExtras
 
-    void $ startTelemetry shakeDb shakeExtras
     startProfilingTelemetry otProfilingEnabled logger $ state shakeExtras
 
     checkParents <- optCheckParents
-    for_ metrics $ \store -> do
-        let readValuesCounter = fromIntegral . countRelevantKeys checkParents <$> getStateKeys shakeExtras
-            readDirtyKeys = fromIntegral . countRelevantKeys checkParents . HSet.toList <$> readTVarIO(dirtyKeys shakeExtras)
-            readIndexPending = fromIntegral . HMap.size <$> readTVarIO (indexPending $ hiedbWriter shakeExtras)
-            readExportsMap = fromIntegral . HMap.size . getExportsMap <$> readTVarIO (exportsMap shakeExtras)
-            readDatabaseCount = fromIntegral . countRelevantKeys checkParents . map fst <$> shakeGetDatabaseKeys shakeDb
-            readDatabaseStep =  fromIntegral <$> shakeGetBuildStep shakeDb
-
-        registerGauge "ghcide.values_count" readValuesCounter store
-        registerGauge "ghcide.dirty_keys_count" readDirtyKeys store
-        registerGauge "ghcide.indexing_pending_count" readIndexPending store
-        registerGauge "ghcide.exports_map_count" readExportsMap store
-        registerGauge "ghcide.database_count" readDatabaseCount store
-        registerCounter "ghcide.num_builds" readDatabaseStep store
 
-    return ideState
+    -- monitoring
+    let readValuesCounter = fromIntegral . countRelevantKeys checkParents <$> getStateKeys shakeExtras
+        readDirtyKeys = fromIntegral . countRelevantKeys checkParents . HSet.toList <$> readTVarIO(dirtyKeys shakeExtras)
+        readIndexPending = fromIntegral . HMap.size <$> readTVarIO (indexPending $ hiedbWriter shakeExtras)
+        readExportsMap = fromIntegral . HMap.size . getExportsMap <$> readTVarIO (exportsMap shakeExtras)
+        readDatabaseCount = fromIntegral . countRelevantKeys checkParents . map fst <$> shakeGetDatabaseKeys shakeDb
+        readDatabaseStep =  fromIntegral <$> shakeGetBuildStep shakeDb
 
-startTelemetry :: ShakeDatabase -> ShakeExtras -> IO (Async ())
-startTelemetry db extras@ShakeExtras{..}
-  | userTracingEnabled = do
-    countKeys <- mkValueObserver "cached keys count"
-    countDirty <- mkValueObserver "dirty keys count"
-    countBuilds <- mkValueObserver "builds count"
-    IdeOptions{optCheckParents} <- getIdeOptionsIO extras
-    checkParents <- optCheckParents
-    regularly 1 $ do
-        observe countKeys . countRelevantKeys checkParents =<< getStateKeys extras
-        readTVarIO dirtyKeys >>= observe countDirty . countRelevantKeys checkParents . HSet.toList
-        shakeGetBuildStep db >>= observe countBuilds
+    registerGauge monitoring "ghcide.values_count" readValuesCounter
+    registerGauge monitoring "ghcide.dirty_keys_count" readDirtyKeys
+    registerGauge monitoring "ghcide.indexing_pending_count" readIndexPending
+    registerGauge monitoring "ghcide.exports_map_count" readExportsMap
+    registerGauge monitoring "ghcide.database_count" readDatabaseCount
+    registerCounter monitoring "ghcide.num_builds" readDatabaseStep
+
+    stopMonitoring <- start monitoring
+
+    let ideState = IdeState{..}
+    return ideState
 
-  | otherwise = async (pure ())
-    where
-        regularly :: Seconds -> IO () -> IO (Async ())
-        regularly delay act = async $ forever (act >> sleep delay)
 
 getStateKeys :: ShakeExtras -> IO [Key]
 getStateKeys = (fmap.fmap) fst . atomically . ListT.toList . STM.listT . state
@@ -679,6 +666,7 @@ shakeShut IdeState{..} = do
     for_ runner cancelShakeSession
     void $ shakeDatabaseProfile shakeDb
     progressStop $ progress shakeExtras
+    stopMonitoring
 
 
 -- | This is a variant of withMVar where the first argument is run unmasked and if it throws
diff --git a/ghcide/src/Development/IDE/Main.hs b/ghcide/src/Development/IDE/Main.hs
index 1180b00afc..f9fc05e161 100644
--- a/ghcide/src/Development/IDE/Main.hs
+++ b/ghcide/src/Development/IDE/Main.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP            #-}
 {-# LANGUAGE PackageImports #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 module Development.IDE.Main
@@ -11,14 +12,12 @@ module Development.IDE.Main
 ,testing
 ,Log(..)
 ) where
-import           Control.Concurrent.Async              (async, waitCatch)
-import           Control.Concurrent.Extra              (killThread, withNumCapabilities)
+import           Control.Concurrent.Extra              (withNumCapabilities)
 import           Control.Concurrent.STM.Stats          (atomically,
                                                         dumpSTMStats)
 import           Control.Exception.Safe                (SomeException, catchAny,
-                                                        displayException,
-                                                        onException)
-import           Control.Monad.Extra                   (concatMapM, join, unless,
+                                                        displayException)
+import           Control.Monad.Extra                   (concatMapM, unless,
                                                         when)
 import qualified Data.Aeson.Encode.Pretty              as A
 import           Data.Default                          (Default (def))
@@ -31,13 +30,11 @@ import           Data.Maybe                            (catMaybes, isJust)
 import qualified Data.Text                             as T
 import           Data.Text.Lazy.Encoding               (decodeUtf8)
 import qualified Data.Text.Lazy.IO                     as LT
-import           Data.Traversable                      (for)
 import           Data.Typeable                         (typeOf)
 import           Development.IDE                       (Action, GhcVersion (..),
                                                         Priority (Debug, Error), Rules,
                                                         ghcVersion,
-                                                        hDuplicateTo',
-                                                        logInfo)
+                                                        hDuplicateTo')
 import           Development.IDE.Core.Debouncer        (Debouncer,
                                                         newAsyncDebouncer)
 import           Development.IDE.Core.FileStore        (isWatchSupported)
@@ -130,12 +127,15 @@ import           System.IO                             (BufferMode (LineBufferin
                                                         hSetEncoding, stderr,
                                                         stdin, stdout, utf8)
 import           System.Random                         (newStdGen)
-import qualified System.Metrics                        as Monitoring
-import           System.Remote.Monitoring.Wai
-import qualified System.Remote.Monitoring.Wai          as Monitoring
 import           System.Time.Extra                     (Seconds, offsetTime,
                                                         showDuration)
 import           Text.Printf                           (printf)
+import Development.IDE.Types.Monitoring (Monitoring)
+import qualified Development.IDE.Monitoring.OpenTelemetry as OpenTelemetry
+
+#ifdef MONITORING_EKG
+import qualified Development.IDE.Monitoring.EKG as EKG
+#endif
 
 data Log
   = LogHeapStats !HeapStats.Log
@@ -238,10 +238,9 @@ data Arguments = Arguments
     , argsHandleIn              :: IO Handle
     , argsHandleOut             :: IO Handle
     , argsThreads               :: Maybe Natural
-    , argsMonitoringPort        :: Maybe Natural
+    , argsMonitoring            :: IO Monitoring
     }
 
-
 defaultArguments :: Recorder (WithPriority Log) -> Logger -> Arguments
 defaultArguments recorder logger = Arguments
         { argsProjectRoot = Nothing
@@ -276,7 +275,10 @@ defaultArguments recorder logger = Arguments
                 -- the language server tests without the redirection.
                 putStr " " >> hFlush stdout
                 return newStdout
-        , argsMonitoringPort = Just 8000
+        , argsMonitoring = OpenTelemetry.monitoring
+#ifdef MONITORING_EKG
+                        <> EKG.monitoring logger 8999
+#endif
         }
 
 
@@ -364,24 +366,7 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                 -- FIXME: Remove this after GHC 9 gets fully supported
                 when (ghcVersion == GHC90) $
                     log Warning LogOnlyPartialGhc9Support
-                server <- fmap join $ for argsMonitoringPort $ \p -> do
-                    store <- Monitoring.newStore
-                    Monitoring.registerGcMetrics store
-                    let startServer = Monitoring.forkServerWith store "localhost" (fromIntegral p)
-                    -- this can fail if the port is busy, throwing an async exception back to us
-                    -- to handle that, wrap the server thread in an async
-                    mb_server <- async startServer >>= waitCatch
-                    case mb_server of
-                        Right s -> do
-                            logInfo logger $ T.pack $
-                                "Started monitoring server on port " <> show p
-                            return $ Just s
-                        Left e -> do
-                            logInfo logger $ T.pack $
-                                "Unable to bind monitoring server on port "
-                                <> show p <> ":" <> show e
-                            return Nothing
-
+                monitoring <- argsMonitoring
                 initialise
                     (cmapWithPrio LogService recorder)
                     argsDefaultHlsConfig
@@ -392,9 +377,7 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                     options
                     withHieDb
                     hieChan
-                    (Monitoring.serverMetricStore <$> server)
-                    `onException`
-                        traverse_ (killThread . serverThreadId) server
+                    monitoring
             dumpSTMStats
         Check argFiles -> do
           dir <- maybe IO.getCurrentDirectory return argsProjectRoot
@@ -427,7 +410,7 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                         , optCheckProject = pure False
                         , optModifyDynFlags = optModifyDynFlags def_options <> pluginModifyDynflags plugins
                         }
-            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan Nothing
+            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan mempty
             shakeSessionInit (cmapWithPrio LogShake recorder) ide
             registerIdeConfiguration (shakeExtras ide) $ IdeConfiguration mempty (hashed Nothing)
 
@@ -480,7 +463,7 @@ defaultMain recorder Arguments{..} = withHeapStats (cmapWithPrio LogHeapStats re
                     , optCheckProject = pure False
                     , optModifyDynFlags = optModifyDynFlags def_options <> pluginModifyDynflags plugins
                     }
-            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan Nothing
+            ide <- initialise (cmapWithPrio LogService recorder) argsDefaultHlsConfig rules Nothing logger debouncer options hiedb hieChan mempty
             shakeSessionInit (cmapWithPrio LogShake recorder) ide
             registerIdeConfiguration (shakeExtras ide) $ IdeConfiguration mempty (hashed Nothing)
             c ide
diff --git a/ghcide/src/Development/IDE/Monitoring/EKG.hs b/ghcide/src/Development/IDE/Monitoring/EKG.hs
new file mode 100644
index 0000000000..3ffe300d07
--- /dev/null
+++ b/ghcide/src/Development/IDE/Monitoring/EKG.hs
@@ -0,0 +1,34 @@
+module Development.IDE.Monitoring.EKG(monitoring) where
+import           Control.Concurrent               (killThread)
+import           Control.Concurrent.Async         (async, waitCatch)
+import           Data.Text                        (pack)
+import           Development.IDE.Types.Logger     (Logger, logInfo)
+import           Development.IDE.Types.Monitoring (Monitoring (..))
+import qualified System.Metrics                   as Monitoring
+import qualified System.Remote.Monitoring.Wai     as Monitoring
+
+-- | Monitoring using EKG
+monitoring :: Logger -> Int -> IO Monitoring
+monitoring logger port = do
+    store <- Monitoring.newStore
+    Monitoring.registerGcMetrics store
+    let registerCounter name read = Monitoring.registerGauge name read store
+        registerGauge name read = Monitoring.registerGauge name read store
+        start = do
+            server <- do
+                let startServer = Monitoring.forkServerWith store "localhost" port
+                -- this can fail if the port is busy, throwing an async exception back to us
+                -- to handle that, wrap the server thread in an async
+                mb_server <- async startServer >>= waitCatch
+                case mb_server of
+                    Right s -> do
+                        logInfo logger $ pack $
+                            "Started monitoring server on port " <> show port
+                        return $ Just s
+                    Left e -> do
+                        logInfo logger $ pack $
+                            "Unable to bind monitoring server on port "
+                            <> show port <> ":" <> show e
+                        return Nothing
+            return $ mapM_ (killThread . Monitoring.serverThreadId) server
+    return $ Monitoring {..}
diff --git a/ghcide/src/Development/IDE/Monitoring/OpenTelemetry.hs b/ghcide/src/Development/IDE/Monitoring/OpenTelemetry.hs
new file mode 100644
index 0000000000..2a6efa3d2e
--- /dev/null
+++ b/ghcide/src/Development/IDE/Monitoring/OpenTelemetry.hs
@@ -0,0 +1,31 @@
+module Development.IDE.Monitoring.OpenTelemetry (monitoring) where
+
+import           Control.Concurrent.Async         (Async, async, cancel)
+import           Control.Monad                    (forever)
+import           Data.IORef.Extra                 (atomicModifyIORef'_,
+                                                   newIORef, readIORef)
+import           Data.Text.Encoding               (encodeUtf8)
+import           Debug.Trace.Flags                (userTracingEnabled)
+import           Development.IDE.Types.Monitoring (Monitoring (..))
+import           OpenTelemetry.Eventlog           (mkValueObserver, observe)
+import           System.Time.Extra                (Seconds, sleep)
+
+-- | Dump monitoring to the eventlog using the Opentelemetry package
+monitoring :: IO Monitoring
+monitoring
+  | userTracingEnabled = do
+    actions <- newIORef []
+    let registerCounter name read = do
+            observer <- mkValueObserver (encodeUtf8 name)
+            let update = observe observer . fromIntegral =<< read
+            atomicModifyIORef'_ actions (update :)
+        registerGauge = registerCounter
+    let start = do
+            a <- regularly 1 $ sequence_ =<< readIORef actions
+            return (cancel a)
+    return Monitoring{..}
+  | otherwise = mempty
+
+
+regularly :: Seconds -> IO () -> IO (Async ())
+regularly delay act = async $ forever (act >> sleep delay)
diff --git a/ghcide/src/Development/IDE/Types/Monitoring.hs b/ghcide/src/Development/IDE/Types/Monitoring.hs
new file mode 100644
index 0000000000..08d3d88128
--- /dev/null
+++ b/ghcide/src/Development/IDE/Types/Monitoring.hs
@@ -0,0 +1,30 @@
+module Development.IDE.Types.Monitoring
+(Monitoring(..)
+) where
+
+import           Data.Int
+import           Data.Text                (Text)
+
+-- | An abstraction for runtime monitoring.
+data Monitoring = Monitoring {
+    registerGauge   :: Text -> IO Int64 -> IO (),
+    registerCounter :: Text -> IO Int64 -> IO (),
+    start :: IO (IO ())
+  }
+
+instance Semigroup Monitoring where
+    a <> b = Monitoring {
+        registerGauge   = \n v -> registerGauge a n v >> registerGauge b n v,
+        registerCounter = \n v -> registerCounter a n v >> registerCounter b n v,
+        start = do
+            a' <- start a
+            b' <- start b
+            return $ a' >> b'
+      }
+
+instance Monoid Monitoring where
+    mempty = Monitoring {
+        registerGauge   = \_ _ -> return (),
+        registerCounter = \_ _ -> return (),
+        start = return $ return ()
+      }

From 55fc507586d7ac1b61aea333af461145b993e92e Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 30 Apr 2022 12:52:52 +0100
Subject: [PATCH 06/15] Add CI for the new flag

---
 .github/workflows/flags.yml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.github/workflows/flags.yml b/.github/workflows/flags.yml
index 2283899d0c..3c7a12a82d 100644
--- a/.github/workflows/flags.yml
+++ b/.github/workflows/flags.yml
@@ -67,6 +67,10 @@ jobs:
       - name: Build `ghcide` with flags
         run: cabal v2-build ghcide --flags="ghc-patched-unboxed-bytecode test-exe executable bench-exe"
 
+      - if: matrix.ghc == '8.10.7'
+        name: Build `ghcide` with ekg
+        run: cabal v2-build ghcide --flags="ekg"
+
       # we have to clean up warnings for 9.0 and 9.2 before enable -WAll
       - if: matrix.ghc != '9.0.2' && matrix.ghc != '9.2.2'
         name: Build with pedantic (-WError)

From 7f69d7b35da823a540b18752330244a590672cdc Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sun, 1 May 2022 15:29:02 +0100
Subject: [PATCH 07/15] fix double ifdef

---
 ghcide/exe/Main.hs | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/ghcide/exe/Main.hs b/ghcide/exe/Main.hs
index ff7e554b5a..ebceff7d45 100644
--- a/ghcide/exe/Main.hs
+++ b/ghcide/exe/Main.hs
@@ -149,8 +149,5 @@ main = withTelemetryLogger $ \telemetryLogger -> do
                 }
 #ifdef MONITORING_EKG
         , IDEMain.argsMonitoring = OpenTelemetry.monitoring <> EKG.monitoring logger argsMonitoringPort
-#ifdef MONITORING_EKG
-#endif
 #endif
-
         }

From 7431cea783f3b92d327635c017dd5de87b4b8774 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sun, 1 May 2022 15:31:17 +0100
Subject: [PATCH 08/15] link to GHC docs for eventlogs

---
 docs/contributing/contributing.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/docs/contributing/contributing.md b/docs/contributing/contributing.md
index b885aa12c6..1907d40856 100644
--- a/docs/contributing/contributing.md
+++ b/docs/contributing/contributing.md
@@ -252,7 +252,7 @@ More details in [bench/README](../../ghcide/bench/README.md)
 
 ### Tracing
 
-HLS records opentelemetry eventlog traces via [opentelemetry](https://hackage.haskell.org/package/opentelemetry). To generate the traces, build with `-eventlog` and run with `+RTS -l`. To visualize the traces, install [Tracy](https://github.com/wolfpld/tracy) and use [eventlog-to-tracy](https://hackage.haskell.org/package/opentelemetry-extra) to open the generated eventlog.
+HLS records opentelemetry [eventlog traces](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/runtime_control.html#rts-eventlog) via [opentelemetry](https://hackage.haskell.org/package/opentelemetry). To generate the traces, build with `-eventlog` and run with `+RTS -l`. To visualize the traces, install [Tracy](https://github.com/wolfpld/tracy) and use [eventlog-to-tracy](https://hackage.haskell.org/package/opentelemetry-extra) to open the generated eventlog.
 
 ## Adding support for a new editor
 

From a5bc2104f722502fbb4971b5d8791cb603459ec4 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sun, 1 May 2022 15:35:09 +0100
Subject: [PATCH 09/15] log when stopping the EKG server

---
 ghcide/src/Development/IDE/Monitoring/EKG.hs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Monitoring/EKG.hs b/ghcide/src/Development/IDE/Monitoring/EKG.hs
index 3ffe300d07..55fe399fe6 100644
--- a/ghcide/src/Development/IDE/Monitoring/EKG.hs
+++ b/ghcide/src/Development/IDE/Monitoring/EKG.hs
@@ -1,6 +1,7 @@
 module Development.IDE.Monitoring.EKG(monitoring) where
 import           Control.Concurrent               (killThread)
 import           Control.Concurrent.Async         (async, waitCatch)
+import           Control.Monad                    (forM_)
 import           Data.Text                        (pack)
 import           Development.IDE.Types.Logger     (Logger, logInfo)
 import           Development.IDE.Types.Monitoring (Monitoring (..))
@@ -30,5 +31,7 @@ monitoring logger port = do
                             "Unable to bind monitoring server on port "
                             <> show port <> ":" <> show e
                         return Nothing
-            return $ mapM_ (killThread . Monitoring.serverThreadId) server
+            return $ forM_ server $ \s -> do
+                logInfo logger "Stopping monitoring server"
+                killThread $ Monitoring.serverThreadId s
     return $ Monitoring {..}

From 629452c4d9d42f5d1bc6b012a905329a616df4b3 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sun, 1 May 2022 15:38:30 +0100
Subject: [PATCH 10/15] Allow CPP in modules

---
 ghcide/.hlint.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ghcide/.hlint.yaml b/ghcide/.hlint.yaml
index 590a707570..c8dde37fa9 100644
--- a/ghcide/.hlint.yaml
+++ b/ghcide/.hlint.yaml
@@ -111,6 +111,7 @@
     - Development.IDE.GHC.Util
     - Development.IDE.Import.FindImports
     - Development.IDE.LSP.Outline
+    - Development.IDE.Main
     - Development.IDE.Spans.Calculate
     - Development.IDE.Spans.Documentation
     - Development.IDE.Spans.Common
@@ -123,6 +124,7 @@
     - Development.IDE.Plugin.Completions.Logic
     - Development.IDE.Types.Location
     - Main
+    - Arguments
 
 - flags:
   - default: false

From c687f4ea5065357776a71512b43faf1ef645269d Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sun, 1 May 2022 15:38:34 +0100
Subject: [PATCH 11/15] Add doc comments

---
 ghcide/src/Development/IDE/Types/Monitoring.hs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Types/Monitoring.hs b/ghcide/src/Development/IDE/Types/Monitoring.hs
index 08d3d88128..22ff92639d 100644
--- a/ghcide/src/Development/IDE/Types/Monitoring.hs
+++ b/ghcide/src/Development/IDE/Types/Monitoring.hs
@@ -5,9 +5,11 @@ module Development.IDE.Types.Monitoring
 import           Data.Int
 import           Data.Text                (Text)
 
--- | An abstraction for runtime monitoring.
+-- | An abstraction for runtime monitoring inspired by the 'ekg' package
 data Monitoring = Monitoring {
+    -- | Register an integer-valued metric.
     registerGauge   :: Text -> IO Int64 -> IO (),
+    -- | Register a non-negative, monotonically increasing, integer-valued metric.
     registerCounter :: Text -> IO Int64 -> IO (),
     start :: IO (IO ())
   }

From 5319cb112310450b03874554d31878bc790a837a Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sun, 1 May 2022 15:38:19 +0100
Subject: [PATCH 12/15] Apply suggestions from code review

Co-authored-by: Michael Peyton Jones <me@michaelpj.com>
---
 cabal.project                                  | 5 ++++-
 ghcide/src/Development/IDE/Monitoring/EKG.hs   | 2 +-
 ghcide/src/Development/IDE/Types/Monitoring.hs | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/cabal.project b/cabal.project
index 122d60eaf1..92f760eb22 100644
--- a/cabal.project
+++ b/cabal.project
@@ -53,7 +53,10 @@ constraints:
   ghc-lib-parser-ex -auto,
   stylish-haskell +ghc-lib
 
- source-repository-package
+-- This is benign and won't affect our ability to release to Hackage,
+-- because we only depend on `ekg-json` when a non-default flag
+-- is turned on.
+source-repository-package
   type:git
   location: https://github.com/vshabanov/ekg-json
   tag: 00ebe7211c981686e65730b7144fbf5350462608
diff --git a/ghcide/src/Development/IDE/Monitoring/EKG.hs b/ghcide/src/Development/IDE/Monitoring/EKG.hs
index 55fe399fe6..38a3ebbea8 100644
--- a/ghcide/src/Development/IDE/Monitoring/EKG.hs
+++ b/ghcide/src/Development/IDE/Monitoring/EKG.hs
@@ -13,7 +13,7 @@ monitoring :: Logger -> Int -> IO Monitoring
 monitoring logger port = do
     store <- Monitoring.newStore
     Monitoring.registerGcMetrics store
-    let registerCounter name read = Monitoring.registerGauge name read store
+    let registerCounter name read = Monitoring.registerCounter name read store
         registerGauge name read = Monitoring.registerGauge name read store
         start = do
             server <- do
diff --git a/ghcide/src/Development/IDE/Types/Monitoring.hs b/ghcide/src/Development/IDE/Types/Monitoring.hs
index 22ff92639d..256381e60a 100644
--- a/ghcide/src/Development/IDE/Types/Monitoring.hs
+++ b/ghcide/src/Development/IDE/Types/Monitoring.hs
@@ -11,7 +11,7 @@ data Monitoring = Monitoring {
     registerGauge   :: Text -> IO Int64 -> IO (),
     -- | Register a non-negative, monotonically increasing, integer-valued metric.
     registerCounter :: Text -> IO Int64 -> IO (),
-    start :: IO (IO ())
+    start :: IO (IO ()) -- ^ Start the monitoring system, returning an action which will stop the system.
   }
 
 instance Semigroup Monitoring where

From ab347bee54f777c002cc33e6bbb350370abeb03a Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Mon, 2 May 2022 10:57:54 +0100
Subject: [PATCH 13/15] Compat. with ghc 9.2

---
 .github/workflows/flags.yml | 6 +-----
 cabal.project               | 2 ++
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/.github/workflows/flags.yml b/.github/workflows/flags.yml
index 3c7a12a82d..7b81bb08e8 100644
--- a/.github/workflows/flags.yml
+++ b/.github/workflows/flags.yml
@@ -65,11 +65,7 @@ jobs:
         run: cabal v2-build hls-graph --flags="embed-files stm-stats"
 
       - name: Build `ghcide` with flags
-        run: cabal v2-build ghcide --flags="ghc-patched-unboxed-bytecode test-exe executable bench-exe"
-
-      - if: matrix.ghc == '8.10.7'
-        name: Build `ghcide` with ekg
-        run: cabal v2-build ghcide --flags="ekg"
+        run: cabal v2-build ghcide --flags="ghc-patched-unboxed-bytecode test-exe executable bench-exe ekg"
 
       # we have to clean up warnings for 9.0 and 9.2 before enable -WAll
       - if: matrix.ghc != '9.0.2' && matrix.ghc != '9.2.2'
diff --git a/cabal.project b/cabal.project
index 92f760eb22..22bd0405e4 100644
--- a/cabal.project
+++ b/cabal.project
@@ -82,7 +82,9 @@ allow-newer:
 
   -- for ekg
   ekg-core:base,
+  ekg-core:ghc-prim,
   ekg-wai:base,
+  ekg-wai:time,
 
   -- for shake-bench
   Chart-diagrams:diagrams-core,

From 700d73f44094ed2f791b63d2da1c7efce52d4c63 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Thu, 5 May 2022 21:50:09 +0100
Subject: [PATCH 14/15] use an ekg-json snapshot that preserves compat. with
 ghc 8.x

---
 cabal.project | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cabal.project b/cabal.project
index 22bd0405e4..4cc16fa34a 100644
--- a/cabal.project
+++ b/cabal.project
@@ -58,8 +58,8 @@ constraints:
 -- is turned on.
 source-repository-package
   type:git
-  location: https://github.com/vshabanov/ekg-json
-  tag: 00ebe7211c981686e65730b7144fbf5350462608
+  location: https://github.com/pepeiborra/ekg-json
+  tag: 7a0af7a8fd38045fd15fb13445bdcc7085325460
   -- https://github.com/tibbe/ekg-json/pull/12
 
 allow-newer:

From e7f3df4db9f9b654f4695f150da2893a717ef8f2 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Fri, 6 May 2022 07:26:32 +0100
Subject: [PATCH 15/15] confine CPP to the EKG module

---
 ghcide/.hlint.yaml                           |  3 ---
 ghcide/exe/Arguments.hs                      |  7 +------
 ghcide/exe/Main.hs                           | 10 ++--------
 ghcide/ghcide.cabal                          |  3 +--
 ghcide/src/Development/IDE/Main.hs           | 15 ++++-----------
 ghcide/src/Development/IDE/Monitoring/EKG.hs | 17 ++++++++++++++---
 6 files changed, 22 insertions(+), 33 deletions(-)

diff --git a/ghcide/.hlint.yaml b/ghcide/.hlint.yaml
index c8dde37fa9..a188671994 100644
--- a/ghcide/.hlint.yaml
+++ b/ghcide/.hlint.yaml
@@ -111,7 +111,6 @@
     - Development.IDE.GHC.Util
     - Development.IDE.Import.FindImports
     - Development.IDE.LSP.Outline
-    - Development.IDE.Main
     - Development.IDE.Spans.Calculate
     - Development.IDE.Spans.Documentation
     - Development.IDE.Spans.Common
@@ -123,8 +122,6 @@
     - Development.IDE.Plugin.Completions
     - Development.IDE.Plugin.Completions.Logic
     - Development.IDE.Types.Location
-    - Main
-    - Arguments
 
 - flags:
   - default: false
diff --git a/ghcide/exe/Arguments.hs b/ghcide/exe/Arguments.hs
index 5a9c443bc6..4d14b920bd 100644
--- a/ghcide/exe/Arguments.hs
+++ b/ghcide/exe/Arguments.hs
@@ -1,7 +1,6 @@
 -- Copyright (c) 2019 The DAML Authors. All rights reserved.
 -- SPDX-License-Identifier: Apache-2.0
 
-{-# LANGUAGE CPP #-}
 module Arguments(Arguments(..), getArguments) where
 
 import           Development.IDE      (IdeState)
@@ -20,9 +19,7 @@ data Arguments = Arguments
     ,argsVerbose                    :: Bool
     ,argsCommand                    :: Command
     ,argsConservativeChangeTracking :: Bool
-#ifdef MONITORING_EKG
     ,argsMonitoringPort             :: Int
-#endif
     }
 
 getArguments :: IdePlugins IdeState -> IO Arguments
@@ -44,9 +41,7 @@ arguments plugins = Arguments
       <*> switch (short 'd' <> long "verbose" <> help "Include internal events in logging output")
       <*> (commandP plugins <|> lspCommand <|> checkCommand)
       <*> switch (long "conservative-change-tracking" <> help "disable reactive change tracking (for testing/debugging)")
-#ifdef MONITORING_EKG
-      <*> option auto (long "monitoring-port" <> metavar "PORT" <> value 8999 <> showDefault <> help "Port to use for monitoring")
-#endif
+      <*> option auto (long "monitoring-port" <> metavar "PORT" <> value 8999 <> showDefault <> help "Port to use for EKG monitoring (if the binary is built with EKG)")
       where
           checkCommand = Check <$> many (argument str (metavar "FILES/DIRS..."))
           lspCommand = LSP <$ flag' True (long "lsp" <> help "Start talking to an LSP client")
diff --git a/ghcide/exe/Main.hs b/ghcide/exe/Main.hs
index ebceff7d45..e97f393d2a 100644
--- a/ghcide/exe/Main.hs
+++ b/ghcide/exe/Main.hs
@@ -1,7 +1,6 @@
 -- Copyright (c) 2019 The DAML Authors. All rights reserved.
 -- SPDX-License-Identifier: Apache-2.0
 {-# OPTIONS_GHC -Wno-dodgy-imports #-} -- GHC no longer exports def in GHC 8.6 and above
-{-# LANGUAGE CPP             #-}
 {-# LANGUAGE TemplateHaskell #-}
 
 module Main(main) where
@@ -20,6 +19,8 @@ import           Development.IDE.Core.Rules        (mainRule)
 import qualified Development.IDE.Core.Rules        as Rules
 import           Development.IDE.Core.Tracing      (withTelemetryLogger)
 import qualified Development.IDE.Main              as IDEMain
+import qualified Development.IDE.Monitoring.OpenTelemetry as OpenTelemetry
+import qualified Development.IDE.Monitoring.EKG    as EKG
 import qualified Development.IDE.Plugin.HLS.GhcIde as GhcIde
 import           Development.IDE.Types.Logger      (Logger (Logger),
                                                     LoggingColumn (DataColumn, PriorityColumn),
@@ -43,11 +44,6 @@ import           System.Exit                       (exitSuccess)
 import           System.IO                         (hPutStrLn, stderr)
 import           System.Info                       (compilerVersion)
 
-#ifdef MONITORING_EKG
-import qualified Development.IDE.Monitoring.OpenTelemetry as OpenTelemetry
-import qualified Development.IDE.Monitoring.EKG as EKG
-#endif
-
 data Log
   = LogIDEMain IDEMain.Log
   | LogRules Rules.Log
@@ -147,7 +143,5 @@ main = withTelemetryLogger $ \telemetryLogger -> do
                 , optCheckProject = pure $ checkProject config
                 , optRunSubset = not argsConservativeChangeTracking
                 }
-#ifdef MONITORING_EKG
         , IDEMain.argsMonitoring = OpenTelemetry.monitoring <> EKG.monitoring logger argsMonitoringPort
-#endif
         }
diff --git a/ghcide/ghcide.cabal b/ghcide/ghcide.cabal
index 4a6109bcc9..030cc88aad 100644
--- a/ghcide/ghcide.cabal
+++ b/ghcide/ghcide.cabal
@@ -187,6 +187,7 @@ library
         Development.IDE.GHC.Util
         Development.IDE.Import.DependencyInformation
         Development.IDE.Import.FindImports
+        Development.IDE.Monitoring.EKG
         Development.IDE.LSP.HoverDefinition
         Development.IDE.LSP.LanguageServer
         Development.IDE.LSP.Outline
@@ -248,8 +249,6 @@ library
             ekg-wai,
             ekg-core,
         cpp-options:   -DMONITORING_EKG
-        exposed-modules:
-            Development.IDE.Monitoring.EKG
 
 flag test-exe
     description: Build the ghcide-test-preprocessor executable
diff --git a/ghcide/src/Development/IDE/Main.hs b/ghcide/src/Development/IDE/Main.hs
index f9fc05e161..5acb2139d5 100644
--- a/ghcide/src/Development/IDE/Main.hs
+++ b/ghcide/src/Development/IDE/Main.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP            #-}
 {-# LANGUAGE PackageImports #-}
 {-# OPTIONS_GHC -Wno-orphans #-}
 module Development.IDE.Main
@@ -63,6 +62,9 @@ import           Development.IDE.LSP.LanguageServer    (runLanguageServer)
 import qualified Development.IDE.LSP.LanguageServer    as LanguageServer
 import           Development.IDE.Main.HeapStats        (withHeapStats)
 import qualified Development.IDE.Main.HeapStats        as HeapStats
+import           Development.IDE.Types.Monitoring      (Monitoring)
+import qualified Development.IDE.Monitoring.EKG as EKG
+import qualified Development.IDE.Monitoring.OpenTelemetry as OpenTelemetry
 import           Development.IDE.Plugin                (Plugin (pluginHandlers, pluginModifyDynflags, pluginRules))
 import           Development.IDE.Plugin.HLS            (asGhcIdePlugin)
 import qualified Development.IDE.Plugin.HLS            as PluginHLS
@@ -130,12 +132,6 @@ import           System.Random                         (newStdGen)
 import           System.Time.Extra                     (Seconds, offsetTime,
                                                         showDuration)
 import           Text.Printf                           (printf)
-import Development.IDE.Types.Monitoring (Monitoring)
-import qualified Development.IDE.Monitoring.OpenTelemetry as OpenTelemetry
-
-#ifdef MONITORING_EKG
-import qualified Development.IDE.Monitoring.EKG as EKG
-#endif
 
 data Log
   = LogHeapStats !HeapStats.Log
@@ -275,10 +271,7 @@ defaultArguments recorder logger = Arguments
                 -- the language server tests without the redirection.
                 putStr " " >> hFlush stdout
                 return newStdout
-        , argsMonitoring = OpenTelemetry.monitoring
-#ifdef MONITORING_EKG
-                        <> EKG.monitoring logger 8999
-#endif
+        , argsMonitoring = OpenTelemetry.monitoring <> EKG.monitoring logger 8999
         }
 
 
diff --git a/ghcide/src/Development/IDE/Monitoring/EKG.hs b/ghcide/src/Development/IDE/Monitoring/EKG.hs
index 38a3ebbea8..84bc85935a 100644
--- a/ghcide/src/Development/IDE/Monitoring/EKG.hs
+++ b/ghcide/src/Development/IDE/Monitoring/EKG.hs
@@ -1,12 +1,16 @@
+{-# LANGUAGE CPP #-}
 module Development.IDE.Monitoring.EKG(monitoring) where
+
+import           Development.IDE.Types.Monitoring (Monitoring (..))
+import           Development.IDE.Types.Logger     (Logger)
+#ifdef MONITORING_EKG
 import           Control.Concurrent               (killThread)
 import           Control.Concurrent.Async         (async, waitCatch)
 import           Control.Monad                    (forM_)
 import           Data.Text                        (pack)
-import           Development.IDE.Types.Logger     (Logger, logInfo)
-import           Development.IDE.Types.Monitoring (Monitoring (..))
-import qualified System.Metrics                   as Monitoring
+import           Development.IDE.Types.Logger     (logInfo)
 import qualified System.Remote.Monitoring.Wai     as Monitoring
+import qualified System.Metrics                   as Monitoring
 
 -- | Monitoring using EKG
 monitoring :: Logger -> Int -> IO Monitoring
@@ -35,3 +39,10 @@ monitoring logger port = do
                 logInfo logger "Stopping monitoring server"
                 killThread $ Monitoring.serverThreadId s
     return $ Monitoring {..}
+
+#else
+
+monitoring :: Logger -> Int -> IO Monitoring
+monitoring _ _ = mempty
+
+#endif