Skip tracing unless eventlog is enabled (#1658)

* Skip tracing unless eventlog is enabled

This was done only for otTracedAction but not for otTracedHandler and otTracedProvider

* fix syntax

* make up a SpanInFlight

* reuse userTracingEnabled

Author: pepeiborra

ghcide/ghcide.cabal

@@ -52,6 +52,7 @@ library
         filepath,
         fingertree,
         ghc-exactprint,
+        ghc-trace-events,
         Glob,
         haddock-library ^>= 1.10.0,
         hashable,

ghcide/src/Development/IDE/Core/Tracing.hs

@@ -6,7 +6,9 @@ module Development.IDE.Core.Tracing
     , startTelemetry
     , measureMemory
     , getInstrumentCached
-    ,otTracedProvider,otSetUri)
+    , otTracedProvider
+    , otSetUri
+    )
 where
 
 import           Control.Concurrent.Async       (Async, async)
@@ -26,6 +28,7 @@ import           Data.IORef                     (modifyIORef', newIORef,
                                                  readIORef, writeIORef)
 import           Data.String                    (IsString (fromString))
 import           Data.Text.Encoding             (encodeUtf8)
+import           Debug.Trace.Flags              (userTracingEnabled)
 import           Development.IDE.Core.RuleTypes (GhcSession (GhcSession),
                                                  GhcSessionDeps (GhcSessionDeps),
                                                  GhcSessionIO (GhcSessionIO))
@@ -36,19 +39,17 @@ import           Development.IDE.Types.Shake    (Key (..), Value,
                                                  Values)
 import           Development.Shake              (Action, actionBracket)
 import           Foreign.Storable               (Storable (sizeOf))
-import           GHC.RTS.Flags
 import           HeapSize                       (recursiveSize, runHeapsize)
 import           Ide.PluginUtils                (installSigUsr1Handler)
 import           Ide.Types                      (PluginId (..))
 import           Language.LSP.Types             (NormalizedFilePath,
                                                  fromNormalizedFilePath)
 import           Numeric.Natural                (Natural)
-import           OpenTelemetry.Eventlog         (Instrument, SpanInFlight,
+import           OpenTelemetry.Eventlog         (Instrument, SpanInFlight (..),
                                                  Synchronicity (Asynchronous),
                                                  addEvent, beginSpan, endSpan,
                                                  mkValueObserver, observe,
                                                  setTag, withSpan, withSpan_)
-import           System.IO.Unsafe               (unsafePerformIO)
 
 -- | Trace a handler using OpenTelemetry. Adds various useful info into tags in the OpenTelemetry span.
 otTracedHandler
@@ -57,27 +58,20 @@ otTracedHandler
     -> String -- ^ Message label
     -> (SpanInFlight -> m a)
     -> m a
-otTracedHandler requestType label act =
-  let !name =
-        if null label
-          then requestType
-          else requestType <> ":" <> show label
-   -- Add an event so all requests can be quickly seen in the viewer without searching
-   in do
-     runInIO <- askRunInIO
-     liftIO $ withSpan (fromString name) (\sp -> addEvent sp "" (fromString $ name <> " received") >> runInIO (act sp))
+otTracedHandler requestType label act
+  | userTracingEnabled = do
+    let !name =
+            if null label
+            then requestType
+            else requestType <> ":" <> show label
+    -- Add an event so all requests can be quickly seen in the viewer without searching
+    runInIO <- askRunInIO
+    liftIO $ withSpan (fromString name) (\sp -> addEvent sp "" (fromString $ name <> " received") >> runInIO (act sp))
+  | otherwise = act (SpanInFlight 0)
 
 otSetUri :: SpanInFlight -> Uri -> IO ()
 otSetUri sp (Uri t) = setTag sp "uri" (encodeUtf8 t)
 
-{-# NOINLINE isTracingEnabled #-}
-isTracingEnabled :: Bool
-isTracingEnabled = unsafePerformIO $ do
-    flags <- getTraceFlags
-    case tracing flags of
-        TraceNone -> return False
-        _         -> return True
-
 -- | Trace a Shake action using opentelemetry.
 otTracedAction
     :: Show k
@@ -87,7 +81,7 @@ otTracedAction
     -> Action a -- ^ The action
     -> Action a
 otTracedAction key file success act
-  | isTracingEnabled =
+  | userTracingEnabled =
     actionBracket
         (do
             sp <- beginSpan (fromString (show key))
@@ -106,11 +100,13 @@ otTracedProvider :: MonadUnliftIO m => PluginId -> ByteString -> m a -> m a
 #else
 otTracedProvider :: MonadUnliftIO m => PluginId -> String -> m a -> m a
 #endif
-otTracedProvider (PluginId pluginName) provider act = do
-  runInIO <- askRunInIO
-  liftIO $ withSpan (provider <> " provider") $ \sp -> do
-    setTag sp "plugin" (encodeUtf8 pluginName)
-    runInIO act
+otTracedProvider (PluginId pluginName) provider act
+  | userTracingEnabled = do
+    runInIO <- askRunInIO
+    liftIO $ withSpan (provider <> " provider") $ \sp -> do
+        setTag sp "plugin" (encodeUtf8 pluginName)
+        runInIO act
+  | otherwise = act
 
 startTelemetry :: Bool -> Logger -> Var Values -> IO ()
 startTelemetry allTheTime logger stateRef = do