fix race condition in symlinks

Author: chase

internal/modulespecifiers/specifiers.go

@@ -363,15 +363,15 @@ func GetEachFileNameOfModule(
 		}
 	}
 
-	symlinkedDirectories := host.GetSymlinkCache().DirectoriesByRealpath()
+	symlinkCache := host.GetSymlinkCache()
 	fullImportedFileName := tspath.GetNormalizedAbsolutePath(importedFileName, cwd)
-	if symlinkedDirectories != nil {
+	if symlinkCache != nil {
 		tspath.ForEachAncestorDirectoryStoppingAtGlobalCache(
 			host.GetGlobalTypingsCacheLocation(),
 			tspath.GetDirectoryPath(fullImportedFileName),
 			func(realPathDirectory string) (bool, bool) {
-				symlinkDirectories := symlinkedDirectories.Get(tspath.ToPath(realPathDirectory, cwd, host.UseCaseSensitiveFileNames()).EnsureTrailingDirectorySeparator())
-				if symlinkDirectories == nil {
+				symlinkSet, ok := symlinkCache.DirectoriesByRealpath().Load(tspath.ToPath(realPathDirectory, cwd, host.UseCaseSensitiveFileNames()).EnsureTrailingDirectorySeparator())
+				if !ok {
 					return false, false
 				} // Continue to ancestor directory
 
@@ -392,15 +392,16 @@ func GetEachFileNameOfModule(
 							UseCaseSensitiveFileNames: host.UseCaseSensitiveFileNames(),
 							CurrentDirectory:          cwd,
 						})
-					for _, symlinkDirectory := range symlinkDirectories {
+					symlinkSet.Range(func(symlinkDirectory string) bool {
 						option := tspath.ResolvePath(symlinkDirectory, relative)
 						results = append(results, ModulePath{
 							FileName:        option,
 							IsInNodeModules: ContainsNodeModules(option),
 							IsRedirect:      target == referenceRedirect,
 						})
 						shouldFilterIgnoredPaths = true // We found a non-ignored path in symlinks, so we can reject ignored-path realpaths
-					}
+						return true
+					})
 				}
 
 				return false, false

internal/symlinks/knownsymlinks.go

@@ -26,7 +26,7 @@ type KnownDirectoryLink struct {
 
 type KnownSymlinks struct {
 	directories               collections.SyncMap[tspath.Path, *KnownDirectoryLink]
-	directoriesByRealpath     collections.MultiMap[tspath.Path, string]
+	directoriesByRealpath     collections.SyncMap[tspath.Path, *collections.SyncSet[string]]
 	files                     collections.SyncMap[tspath.Path, string]
 	HasProcessedResolutions   bool
 	populatedPackages         collections.SyncMap[string, struct{}]
@@ -39,7 +39,7 @@ func (cache *KnownSymlinks) Directories() *collections.SyncMap[tspath.Path, *Kno
 	return &cache.directories
 }
 
-func (cache *KnownSymlinks) DirectoriesByRealpath() *collections.MultiMap[tspath.Path, string] {
+func (cache *KnownSymlinks) DirectoriesByRealpath() *collections.SyncMap[tspath.Path, *collections.SyncSet[string]] {
 	return &cache.directoriesByRealpath
 }
 
@@ -51,7 +51,8 @@ func (cache *KnownSymlinks) Files() *collections.SyncMap[tspath.Path, string] {
 func (cache *KnownSymlinks) SetDirectory(symlink string, symlinkPath tspath.Path, realDirectory *KnownDirectoryLink) {
 	if realDirectory != nil {
 		if _, ok := cache.directories.Load(symlinkPath); !ok {
-			cache.directoriesByRealpath.Add(realDirectory.RealPath, symlink)
+			set, _ := cache.directoriesByRealpath.LoadOrStore(realDirectory.RealPath, &collections.SyncSet[string]{})
+			set.Add(symlink)
 		}
 	}
 	cache.directories.Store(symlinkPath, realDirectory)

internal/symlinks/knownsymlinks_test.go

@@ -50,12 +50,12 @@ func TestSetDirectory(t *testing.T) {
 	}
 
 	// Check that realpath mapping was created
-	realpaths := cache.DirectoriesByRealpath().Get(realDirectory.RealPath)
-	if len(realpaths) == 0 {
+	set, ok := cache.DirectoriesByRealpath().Load(realDirectory.RealPath)
+	if !ok || set.Size() == 0 {
 		t.Fatal("Expected realpath mapping to be created")
 	}
-	if realpaths[0] != "/test/symlink" {
-		t.Errorf("Expected symlink to be '/test/symlink', got '%s'", realpaths[0])
+	if !set.Has("/test/symlink") {
+		t.Error("Expected symlink '/test/symlink' to be in set")
 	}
 }