fix for race condition in FileIndex.fileIndexOfFile

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -15,6 +15,7 @@
 * Fix locals allocating for the special `copyOfStruct` defensive copy ([PR #18025](https://github.com/dotnet/fsharp/pull/18025))
 * Fix lowering of computed array expressions when the expression consists of a simple mapping from a `uint64` or `unativeint` array. [PR #18081](https://github.com/dotnet/fsharp/pull/18081)
 * Add missing nullable-metadata for C# consumers of records,exceptions and DU subtypes generated from F# code. [PR #18079](https://github.com/dotnet/fsharp/pull/18079)
+* Fix a race condition in file book keeping in the compiler service ([#18008](https://github.com/dotnet/fsharp/pull/18008))
 
 
 ### Added

src/Compiler/Utilities/range.fs

@@ -196,38 +196,43 @@ type FileIndexTable() =
         match fileToIndexTable.TryGetValue filePath with
         | true, idx -> idx
         | _ ->
-
-            // Try again looking for a normalized entry.
-            let normalizedFilePath =
-                if normalize then
-                    FileSystem.NormalizePathShim filePath
-                else
-                    filePath
-
-            match fileToIndexTable.TryGetValue normalizedFilePath with
-            | true, idx ->
-                // Record the non-normalized entry if necessary
-                if filePath <> normalizedFilePath then
-                    lock fileToIndexTable (fun () -> fileToIndexTable[filePath] <- idx)
-
-                // Return the index
-                idx
-
-            | _ ->
-                lock fileToIndexTable (fun () ->
-                    // Get the new index
-                    let idx = indexToFileTable.Count
-
-                    // Record the normalized entry
-                    indexToFileTable.Add normalizedFilePath
-                    fileToIndexTable[normalizedFilePath] <- idx
-
-                    // Record the non-normalized entry if necessary
-                    if filePath <> normalizedFilePath then
-                        fileToIndexTable[filePath] <- idx
-
-                    // Return the index
-                    idx)
+            // If a write operation can happen, we have to lock the whole read-check-write to avoid race conditions
+            lock fileToIndexTable
+            <| fun () ->
+                match fileToIndexTable.TryGetValue filePath with
+                | true, idx -> idx
+                | _ ->
+
+                    // Try again looking for a normalized entry.
+                    let normalizedFilePath =
+                        if normalize then
+                            FileSystem.NormalizePathShim filePath
+                        else
+                            filePath
+
+                    match fileToIndexTable.TryGetValue normalizedFilePath with
+                    | true, idx ->
+                        // Record the non-normalized entry if necessary
+                        if filePath <> normalizedFilePath then
+                            fileToIndexTable[filePath] <- idx
+
+                        // Return the index
+                        idx
+
+                    | _ ->
+                        // Get the new index
+                        let idx = indexToFileTable.Count
+
+                        // Record the normalized entry
+                        indexToFileTable.Add normalizedFilePath
+                        fileToIndexTable[normalizedFilePath] <- idx
+
+                        // Record the non-normalized entry if necessary
+                        if filePath <> normalizedFilePath then
+                            fileToIndexTable[filePath] <- idx
+
+                        // Return the index
+                        idx
 
     member t.IndexToFile n =
         if n < 0 then

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -317,6 +317,7 @@
     <Compile Include="Miscellaneous\MigratedOverloadTests.fs" />
     <Compile Include="Miscellaneous\MigratedTypeCheckTests.fs" />
     <Compile Include="Miscellaneous\GraphTests.fs" />
+    <Compile Include="Miscellaneous\FileIndex.fs" />
     <Compile Include="Signatures\TestHelpers.fs" />
     <Compile Include="Signatures\ModuleOrNamespaceTests.fs" />
     <Compile Include="Signatures\RecordTests.fs" />

tests/FSharp.Compiler.ComponentTests/Miscellaneous/FileIndex.fs

@@ -0,0 +1,21 @@
+module Miscellaneous.FileIndex
+
+open FSharp.Compiler.Text
+open System.Threading.Tasks
+open Xunit
+
+// This is a regression test for a bug that existed in FileIndex.fileIndexOfFile
+[<Fact>]
+let NoRaceCondition() =
+    let parallelOptions = ParallelOptions()
+    let mutable count = 10000
+    while count > 0 do
+        let file = $"test{count}.fs"
+        let files = Array.create 2 file
+        let indices = Array.create 2 -1
+        let getFileIndex i = indices[i] <- FileIndex.fileIndexOfFile files[i]
+        Parallel.For(0, files.Length, parallelOptions, getFileIndex) |> ignore
+        if indices[0] <> indices[1] then
+            Assert.Fail $"Found different indices: {indices[0]} and {indices[1]}"
+        count <- count - 1
+

tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_net9.0.bsl

@@ -59,7 +59,7 @@
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.AbstractIL.IL::parseILVersion(string)][offset 0x0000000B][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.AbstractIL.IL::parseILVersion(string)][offset 0x00000021][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$FSharp.Compiler.DiagnosticsLogger::.cctor()][offset 0x000000CD][found Char] Unexpected type on the stack.
-[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@543::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
+[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@548::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000037][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000043][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Internal.Utilities.XmlAdapters::.cctor()][offset 0x0000000A][found Char] Unexpected type on the stack.

tests/ILVerify/ilverify_FSharp.Compiler.Service_Debug_netstandard2.0.bsl

@@ -84,7 +84,7 @@
 [IL]: Error [StackUnexpected]: : Internal.Utilities.FSharpEnvironment+probePathForDotnetHost@321::Invoke([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x00000028][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CodeAnalysis.SimulatedMSBuildReferenceResolver+Pipe #6 input at line 68@68::FSharp.Compiler.CodeAnalysis.ILegacyReferenceResolver.Resolve([FSharp.Compiler.Service]FSharp.Compiler.CodeAnalysis.LegacyResolutionEnvironment, [S.P.CoreLib]System.Tuple`2<string,string>[], string, [FSharp.Core]Microsoft.FSharp.Collections.FSharpList`1<string>, string, string, [FSharp.Core]Microsoft.FSharp.Collections.FSharpList`1<string>, string, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<string,Microsoft.FSharp.Core.Unit>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<bool,Microsoft.FSharp.Core.FSharpFunc`2<string,Microsoft.FSharp.Core.FSharpFunc`2<string,Microsoft.FSharp.Core.Unit>>>)][offset 0x0000034D][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$FSharp.Compiler.DiagnosticsLogger::.cctor()][offset 0x000000CD][found Char] Unexpected type on the stack.
-[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@543::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
+[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@548::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000037][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000043][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Internal.Utilities.XmlAdapters::.cctor()][offset 0x0000000A][found Char] Unexpected type on the stack.

tests/ILVerify/ilverify_FSharp.Compiler.Service_Release_net9.0.bsl

@@ -85,7 +85,7 @@
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.AbstractIL.IL::parseILVersion(string)][offset 0x0000000B][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.AbstractIL.IL::parseILVersion(string)][offset 0x00000021][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$FSharp.Compiler.DiagnosticsLogger::.cctor()][offset 0x000000B6][found Char] Unexpected type on the stack.
-[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@543::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
+[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@548::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000035][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000041][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Internal.Utilities.XmlAdapters::.cctor()][offset 0x0000000A][found Char] Unexpected type on the stack.

tests/ILVerify/ilverify_FSharp.Compiler.Service_Release_netstandard2.0.bsl

@@ -111,7 +111,7 @@
 [IL]: Error [StackUnexpected]: : Internal.Utilities.FSharpEnvironment::probePathForDotnetHost@320([FSharp.Core]Microsoft.FSharp.Core.Unit)][offset 0x0000002A][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : FSharp.Compiler.CodeAnalysis.SimulatedMSBuildReferenceResolver+SimulatedMSBuildResolver@68::FSharp.Compiler.CodeAnalysis.ILegacyReferenceResolver.Resolve([FSharp.Compiler.Service]FSharp.Compiler.CodeAnalysis.LegacyResolutionEnvironment, [S.P.CoreLib]System.Tuple`2<string,string>[], string, [FSharp.Core]Microsoft.FSharp.Collections.FSharpList`1<string>, string, string, [FSharp.Core]Microsoft.FSharp.Collections.FSharpList`1<string>, string, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<string,Microsoft.FSharp.Core.Unit>, [FSharp.Core]Microsoft.FSharp.Core.FSharpFunc`2<bool,Microsoft.FSharp.Core.FSharpFunc`2<string,Microsoft.FSharp.Core.FSharpFunc`2<string,Microsoft.FSharp.Core.Unit>>>)][offset 0x000002F5][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$FSharp.Compiler.DiagnosticsLogger::.cctor()][offset 0x000000B6][found Char] Unexpected type on the stack.
-[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@543::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
+[IL]: Error [CallVirtOnValueType]: : FSharp.Compiler.Text.RangeModule+comparer@548::System.Collections.Generic.IEqualityComparer<FSharp.Compiler.Text.Range>.GetHashCode([FSharp.Compiler.Service]FSharp.Compiler.Text.Range)][offset 0x00000002] Callvirt on a value type method.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000035][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : Internal.Utilities.PathMapModule::applyDir([FSharp.Compiler.Service]Internal.Utilities.PathMap, string)][offset 0x00000041][found Char] Unexpected type on the stack.
 [IL]: Error [StackUnexpected]: : <StartupCode$FSharp-Compiler-Service>.$Internal.Utilities.XmlAdapters::.cctor()][offset 0x0000000A][found Char] Unexpected type on the stack.