FsharpCompilerService benchmark for changes in a cascade of files referencing each other (#14096)

* Generating cascading project
* Benchmark attributes added

tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FSharp.Compiler.Benchmarks.fsproj

@@ -17,6 +17,7 @@
     <Compile Include="SourceText.fs" />
     <Compile Include="DecentlySizedStandAloneFileBenchmark.fs" />
     <Compile Include="CompilerServiceBenchmarks.fs" />
+    <Compile Include="FileCascadeBenchmarks.fs" />
     <Compile Include="Program.fs" />
   </ItemGroup>
 

tests/benchmarks/FCSBenchmarks/CompilerServiceBenchmarks/FileCascadeBenchmarks.fs

+namespace FSharp.Compiler.Benchmarks
+
+open System
+open System.IO
+open System.Text
+open FSharp.Compiler.CodeAnalysis
+open FSharp.Compiler.Diagnostics
+open FSharp.Compiler.EditorServices
+open FSharp.Compiler.Text
+open FSharp.Compiler.AbstractIL.IL
+open FSharp.Compiler.AbstractIL.ILBinaryReader
+open BenchmarkDotNet.Attributes
+open FSharp.Compiler.Benchmarks
+open Microsoft.CodeAnalysis.Text
+open BenchmarkDotNet.Order
+open BenchmarkDotNet.Mathematics
+
+[<AutoOpen>]
+module private CascadeProjectHelpers =
+        
+    let createProject files projectFilename =       
+        {
+            ProjectFileName = projectFilename
+            ProjectId = None
+            SourceFiles = files
+            OtherOptions =  [|"--optimize+" |] 
+            ReferencedProjects = [||]
+            IsIncompleteTypeCheckEnvironment = false
+            UseScriptResolutionRules = false
+            LoadTime = DateTime()
+            UnresolvedReferences = None
+            OriginalLoadReferences = []
+            Stamp = Some 0L (* set the stamp to 0L on each run so we don't evaluate the whole project again *)
+        }
+
+    let baselineModule =
+        $"""
+module Benchmark0
+let returnValue = 5
+let myFunc0 () = 5"""
+
+    let generateSourceCode number =
+        $"""
+module Benchmark%i{number}
+open Benchmark%i{number-1}
+let myFunc%i{number} () = myFunc%i{number-1}()
+//$COMMENTAREA$"""
+
+[<MemoryDiagnoser>]
+[<LongRunJob>]
+[<Orderer(SummaryOrderPolicy.FastestToSlowest)>]
+[<RankColumn(NumeralSystem.Roman)>]
+type FileCascadeBenchmarks() = 
+    let mutable project : FSharpProjectOptions option = None
+
+    let getProject() = project.Value
+    
+    let checker = FSharpChecker.Create(projectCacheSize = 5, enableParallelCheckingWithSignatureFiles = true, parallelReferenceResolution = true)
+    let filesToCreate = 64
+
+    let mutable finalFileContents = SourceText.ofString ""
+        
+    [<GlobalSetup>]
+    member _.Setup() =
+        let projectFolder = Directory.CreateDirectory(Path.Combine(Directory.GetCurrentDirectory(),"CascadeBenchmarkProject"))                    
+        if(projectFolder.Exists) then
+            do projectFolder.Delete(recursive=true)
+        do Directory.CreateDirectory(projectFolder.FullName) |> ignore
+
+        let inProjectFolder fileName = Path.Combine(projectFolder.FullName,fileName)
+
+        File.WriteAllText(inProjectFolder "Benchmark0.fs",baselineModule)
+        for i = 1 to filesToCreate do
+            File.WriteAllText(inProjectFolder $"Benchmark%i{i}.fs", generateSourceCode i)
+
+        let dllFileName = inProjectFolder "CascadingBenchMark.dll"
+        let allSourceCodeFiles = [| for i in 0 .. filesToCreate -> inProjectFolder $"Benchmark%i{i}.fs"|]
+        let x = createProject allSourceCodeFiles dllFileName
+        project <- Some x
+        finalFileContents <- generateSourceCode filesToCreate |> SourceText.ofString
+
+
+    member x.ChangeFile(fileIndex:int, action) = 
+        let project = getProject()
+        let fileName = project.SourceFiles.[fileIndex]
+        let fullOriginalSource = File.ReadAllText(fileName)
+        try
+            File.WriteAllText(fileName, fullOriginalSource.Replace("$COMMENTAREA$","$FILEMODIFIED"))
+            action()
+        finally
+            File.WriteAllText(fileName,fullOriginalSource)
+
+    member x.CheckFinalFile () =
+        let project = getProject()
+        let lastFile = project.SourceFiles |> Array.last
+        checker.ParseAndCheckFileInProject(lastFile,999,finalFileContents,project)
+               
+    [<Benchmark>]
+    member x.ParseProjectAsIs() =
+        x.CheckFinalFile()
+
+    [<Benchmark(Baseline=true)>]
+    member x.ParseProjectWithFullCacheClear() =
+        checker.ClearCache([getProject()])
+        checker.InvalidateConfiguration(getProject())
+        x.CheckFinalFile()
+
+    [<Benchmark>]
+    member x.ParseProjectWithChangingFirstFile() =
+        x.ChangeFile(fileIndex=0, action= fun () -> x.CheckFinalFile())  
+
+    [<Benchmark>]
+    member x.ParseProjectWithChanging25thPercentileFile() =
+        x.ChangeFile(fileIndex=filesToCreate/4, action= fun () -> x.CheckFinalFile())  
+
+    [<Benchmark>]
+    member x.ParseProjectWithChangingMiddleFile() =
+        x.ChangeFile(fileIndex=filesToCreate/2, action= fun () -> x.CheckFinalFile())  
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