Optimize LSP mixin loading and updates

- Store and track mixin filenames per URI in storage
- Avoid reading files that are already cached in storage (opened by editor or loaded previously)
- Only read newly added mixins during updates
- Bump document refresh debounce to 500ms to reduce index jitter

Author: kindermax

internal/lsp/debounce.go

@@ -30,6 +30,7 @@ func (d *documentDebouncer) Schedule(uri string) {
 	}
 
 	var timer *time.Timer
+
 	timer = time.AfterFunc(d.delay, func() {
 		d.fire(uri, timer)
 	})
@@ -49,6 +50,7 @@ func (d *documentDebouncer) Stop() {
 
 func (d *documentDebouncer) fire(uri string, timer *time.Timer) {
 	d.mu.Lock()
+
 	current, ok := d.timers[uri]
 	if !ok || current != timer {
 		d.mu.Unlock()

internal/lsp/handlers.go

@@ -40,6 +40,7 @@ func (s *lspServer) shutdown(context *glsp.Context) error {
 	}
 
 	lsp.SetTraceValue(lsp.TraceValueOff)
+
 	return nil
 }
 
@@ -57,8 +58,25 @@ func (s *lspServer) loadMixins(uri string) {
 
 	path := normalizePath(uri)
 
-	for _, filename := range s.parser.getMixinFilenames(doc) {
+	currentMixins := s.parser.getMixinFilenames(doc)
+	previousMixins := s.storage.GetMixins(uri)
+
+	s.storage.SetMixins(uri, currentMixins)
+
+	for _, filename := range currentMixins {
+		if slices.Contains(previousMixins, filename) {
+			continue
+		}
+
 		mixinPath := replacePathFilename(path, strings.TrimPrefix(filename, "-"))
+		mixinURI := pathToURI(mixinPath)
+
+		// skip if the document is already managed by the storage
+		// e.g. opened manually in the editor or already loaded
+		if s.storage.GetDocument(mixinURI) != nil {
+			continue
+		}
+
 		if !util.FileExists(mixinPath) {
 			s.log.Debugf("mixin target does not exist: %s", mixinPath)
 			continue
@@ -70,7 +88,8 @@ func (s *lspServer) loadMixins(uri string) {
 			continue
 		}
 
-		mixinURI := pathToURI(mixinPath)
+		s.log.Debugf("load mixin %s", mixinPath)
+
 		text := string(data)
 
 		s.storage.AddDocument(mixinURI, text)
@@ -101,6 +120,7 @@ func (s *lspServer) textDocumentDidChange(context *glsp.Context, params *lsp.Did
 		switch c := change.(type) {
 		case lsp.TextDocumentContentChangeEventWhole:
 			s.storage.AddDocument(params.TextDocument.URI, c.Text)
+
 			if s.refresh != nil {
 				s.refresh.Schedule(params.TextDocument.URI)
 			} else {

internal/lsp/server.go

@@ -11,8 +11,10 @@ import (
 	"github.com/tliron/glsp/server"
 )
 
-const lsName = "lets_ls"
-const documentRefreshDebounce = 200 * time.Millisecond
+const (
+	lsName                  = "lets_ls"
+	documentRefreshDebounce = 500 * time.Millisecond
+)
 
 var handler lsp.Handler
 

internal/lsp/storage.go

@@ -5,11 +5,13 @@ import "sync"
 type storage struct {
 	mu        sync.RWMutex
 	documents map[string]*string
+	mixins    map[string][]string
 }
 
 func newStorage() *storage {
 	return &storage{
 		documents: make(map[string]*string),
+		mixins:    make(map[string][]string),
 	}
 }
 
@@ -26,3 +28,17 @@ func (s *storage) AddDocument(uri string, text string) {
 
 	s.documents[uri] = &text
 }
+
+func (s *storage) SetMixins(uri string, mixins []string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.mixins[uri] = mixins
+}
+
+func (s *storage) GetMixins(uri string) []string {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	return s.mixins[uri]
+}

internal/settings/settings.go

@@ -51,8 +51,10 @@ func LoadFile(path string) (Settings, error) {
 	defer file.Close()
 
 	var fileSettings FileSettings
+
 	decoder := yaml.NewDecoder(file)
 	decoder.KnownFields(true)
+
 	if err := decoder.Decode(&fileSettings); err != nil {
 		return Settings{}, fmt.Errorf("failed to decode settings file: %w", err)
 	}