given that we need to clear and resize the ScriptClosureCache under a lock, it might be a better approach to just use the one from the BackgroundCompiler

Author: dawedawe

src/Compiler/Service/BackgroundCompiler.fs

@@ -173,6 +173,8 @@ type internal IBackgroundCompiler =
 
     abstract member ProjectChecked: IEvent<FSharpProjectOptions>
 
+    abstract member ScriptClosureCache: MruCache<AnyCallerThreadToken, FSharpProjectOptions, LoadClosure>
+
 type internal ParseCacheLockToken() =
     interface LockToken
 
@@ -1678,3 +1680,5 @@ type internal BackgroundCompiler
                 userOpName: string
             ) : (FSharpParseFileResults * FSharpCheckFileResults * SourceTextHash) option =
             self.TryGetRecentCheckResultsForFile(fileName, options, sourceText, userOpName)
+
+        member _.ScriptClosureCache = scriptClosureCache

src/Compiler/Service/BackgroundCompiler.fsi

@@ -1,12 +1,15 @@
 namespace FSharp.Compiler.CodeAnalysis
 
+open FSharp.Compiler.ScriptClosure
 open FSharp.Compiler.Text
 open FSharp.Compiler.BuildGraph
 
 open System.Reflection
 open FSharp.Compiler.CodeAnalysis
 open FSharp.Compiler.CompilerConfig
 open FSharp.Compiler.Diagnostics
+open Internal.Utilities.Collections
+open Internal.Utilities.Library
 
 type SourceTextHash = int64
 
@@ -163,6 +166,8 @@ type internal IBackgroundCompiler =
 
     abstract ProjectChecked: IEvent<FSharpProjectOptions>
 
+    abstract ScriptClosureCache: MruCache<AnyCallerThreadToken, FSharpProjectOptions, LoadClosure>
+
 [<AutoOpen>]
 module internal EnvMisc =
 

src/Compiler/Service/TransparentCompiler.fs

@@ -346,14 +346,6 @@ type internal TransparentCompiler
     let fileChecked = Event<string * FSharpProjectOptions>()
     let projectChecked = Event<FSharpProjectOptions>()
 
-    /// Information about the derived script closure.
-    let scriptClosureCache =
-        MruCache<AnyCallerThreadToken, FSharpProjectOptions, LoadClosure>(
-            projectCacheSize,
-            areSame = FSharpProjectOptions.AreSameForChecking,
-            areSimilar = FSharpProjectOptions.UseSameProject
-        )
-
     // use this to process not-yet-implemented tasks
     let backgroundCompiler =
         BackgroundCompiler(
@@ -560,7 +552,7 @@ type internal TransparentCompiler
             getProjectReferences projectSnapshot "ComputeTcConfigBuilder"
 
         let loadClosureOpt: LoadClosure option =
-            scriptClosureCache.TryGet(AnyCallerThread, projectSnapshot.ToOptions())
+            backgroundCompiler.ScriptClosureCache.TryGet(AnyCallerThread, projectSnapshot.ToOptions())
 
         let getSwitchValue (switchString: string) =
             match commandLineArgs |> List.tryFindIndex (fun s -> s.StartsWithOrdinal switchString) with
@@ -1417,7 +1409,7 @@ type internal TransparentCompiler
                         [| yield! creationDiags; yield! extraDiagnostics; yield! tcDiagnostics |]
 
                     let loadClosure =
-                        scriptClosureCache.TryGet(AnyCallerThread, projectSnapshot.ToOptions())
+                        backgroundCompiler.ScriptClosureCache.TryGet(AnyCallerThread, projectSnapshot.ToOptions())
 
                     let typedResults =
                         FSharpCheckFileResults.Make(
@@ -2078,3 +2070,5 @@ type internal TransparentCompiler
                 userOpName: string
             ) : (FSharpParseFileResults * FSharpCheckFileResults * SourceTextHash) option =
             backgroundCompiler.TryGetRecentCheckResultsForFile(fileName, options, sourceText, userOpName)
+
+        member _.ScriptClosureCache = backgroundCompiler.ScriptClosureCache