lsp: Load config from parent dirs (#650)

* lsp: Load config from parent dirs

Fixes #626

Signed-off-by: Charlie Egan <charlie@styra.com>

* lsp: watcher error, use :=

Signed-off-by: Charlie Egan <charlie@styra.com>

* lsp: Wait in server tests

Server tests refactored a little to allow messages to be sent in a
different order.

Signed-off-by: Charlie Egan <charlie@styra.com>

* lsp: PR review comments

Signed-off-by: Charlie Egan <charlie@styra.com>

* lsp: further reduce the config watch timeout

Signed-off-by: Charlie Egan <charlie@styra.com>

* lsp: server test use shared timeout

Signed-off-by: Charlie Egan <charlie@styra.com>

---------

Signed-off-by: Charlie Egan <charlie@styra.com>

cmd/languageserver.go

@@ -43,6 +43,7 @@ func init() {
 			go ls.StartDiagnosticsWorker(ctx)
 			go ls.StartHoverWorker(ctx)
 			go ls.StartCommandWorker(ctx)
+			go ls.StartConfigWorker(ctx)
 
 			sigChan := make(chan os.Signal, 1)
 			signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)

go.mod

@@ -7,6 +7,7 @@ toolchain go1.22.0
 require (
 	dario.cat/mergo v1.0.0
 	github.com/fatih/color v1.16.0
+	github.com/fsnotify/fsnotify v1.7.0
 	github.com/gobwas/glob v0.2.3
 	github.com/google/go-cmp v0.6.0
 	github.com/olekukonko/tablewriter v0.0.5

go.sum

@@ -44,6 +44,8 @@ github.com/fortytw2/leaktest v1.3.0 h1:u8491cBMTQ8ft8aeV+adlcytMZylmA5nnwwkRZjI8
 github.com/fortytw2/leaktest v1.3.0/go.mod h1:jDsjWgpAGjm2CA7WthBh/CdZYEPF31XHquHwclZch5g=
 github.com/foxcpp/go-mockdns v1.1.0 h1:jI0rD8M0wuYAxL7r/ynTrCQQq0BVqfB99Vgk7DlmewI=
 github.com/foxcpp/go-mockdns v1.1.0/go.mod h1:IhLeSFGed3mJIAXPH2aiRQB+kqz7oqu8ld2qVbOu7Wk=
+github.com/fsnotify/fsnotify v1.7.0 h1:8JEhPFa5W2WU7YfeZzPNqzMP6Lwt7L2715Ggo0nosvA=
+github.com/fsnotify/fsnotify v1.7.0/go.mod h1:40Bi/Hjc2AVfZrqy+aj+yEI+/bRxZnMJyTJwOpGvigM=
 github.com/gdamore/encoding v1.0.0 h1:+7OoQ1Bc6eTm5niUzBa0Ctsh6JbMW6Ra+YNuAtDBdko=
 github.com/gdamore/encoding v1.0.0/go.mod h1:alR0ol34c49FCSBLjhosxzcPHQbf2trDkoo5dl+VrEg=
 github.com/gdamore/tcell v1.1.4/go.mod h1:Hjvr+Ofd+gLglo7RYKxxnzCBmev3BzsS67MebKS4zMM=

internal/lsp/clients/clients.go

@@ -7,9 +7,14 @@ type Identifier int
 const (
 	IdentifierGeneric Identifier = iota
 	IdentifierVSCode
+	IdentifierGoTest
 )
 
 func DetermineClientIdentifier(clientName string) Identifier {
+	if clientName == "go test" {
+		return IdentifierGoTest
+	}
+
 	if clientName == "Visual Studio Code" {
 		return IdentifierVSCode
 	}

internal/lsp/config/watcher.go

@@ -0,0 +1,132 @@
+package config
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"github.com/fsnotify/fsnotify"
+)
+
+type Watcher struct {
+	Reload chan string
+	Drop   chan struct{}
+
+	path        string
+	pathUpdates chan string
+
+	fsWatcher *fsnotify.Watcher
+
+	errorWriter io.Writer
+}
+
+type WatcherOpts struct {
+	ErrorWriter io.Writer
+	Path        string
+}
+
+func NewWatcher(opts *WatcherOpts) *Watcher {
+	w := &Watcher{
+		Reload:      make(chan string, 1),
+		Drop:        make(chan struct{}, 1),
+		pathUpdates: make(chan string, 1),
+	}
+
+	if opts != nil {
+		w.errorWriter = opts.ErrorWriter
+		w.path = opts.Path
+	}
+
+	return w
+}
+
+func (w *Watcher) Start(ctx context.Context) error {
+	err := w.Stop()
+	if err != nil {
+		return fmt.Errorf("failed to stop existing watcher: %w", err)
+	}
+
+	w.fsWatcher, err = fsnotify.NewWatcher()
+	if err != nil {
+		return fmt.Errorf("failed to create fsnotify watcher: %w", err)
+	}
+
+	go func() {
+		w.loop(ctx)
+	}()
+
+	return nil
+}
+
+func (w *Watcher) loop(ctx context.Context) {
+	for {
+		select {
+		case path := <-w.pathUpdates:
+			if w.path != "" {
+				err := w.fsWatcher.Remove(w.path)
+				if err != nil {
+					fmt.Fprintf(w.errorWriter, "failed to remove existing watch: %v\n", err)
+				}
+			}
+
+			err := w.fsWatcher.Add(path)
+			if err != nil {
+				fmt.Fprintf(w.errorWriter, "failed to add watch: %v\n", err)
+			}
+
+			w.path = path
+
+			// when the path itself is changed, then this is an event too
+			w.Reload <- path
+		case event, ok := <-w.fsWatcher.Events:
+			if !ok {
+				fmt.Fprintf(w.errorWriter, "config watcher event channel closed\n")
+
+				return
+			}
+
+			if event.Has(fsnotify.Write) {
+				w.Reload <- event.Name
+			}
+
+			if event.Has(fsnotify.Remove) || event.Has(fsnotify.Rename) {
+				w.path = ""
+				w.Drop <- struct{}{}
+			}
+		case err := <-w.fsWatcher.Errors:
+			fmt.Fprintf(w.errorWriter, "config watcher error: %v\n", err)
+		case <-ctx.Done():
+			err := w.Stop()
+			if err != nil {
+				fmt.Fprintf(w.errorWriter, "failed to stop watcher: %v\n", err)
+			}
+
+			return
+		}
+	}
+}
+
+func (w *Watcher) Watch(configFilePath string) {
+	w.pathUpdates <- configFilePath
+}
+
+func (w *Watcher) Stop() error {
+	if w.fsWatcher != nil {
+		err := w.fsWatcher.Close()
+		if err != nil {
+			return fmt.Errorf("failed to close fsnotify watcher: %w", err)
+		}
+
+		return nil
+	}
+
+	return nil
+}
+
+func (w *Watcher) IsWatching() bool {
+	if w.fsWatcher == nil {
+		return false
+	}
+
+	return len(w.fsWatcher.WatchList()) > 0
+}

internal/lsp/config/watcher_test.go

@@ -0,0 +1,71 @@
+package config
+
+import (
+	"context"
+	"os"
+	"testing"
+	"time"
+)
+
+func TestWatcher(t *testing.T) {
+	t.Parallel()
+
+	tempDir := t.TempDir()
+
+	configFilePath := tempDir + "/config.yaml"
+
+	configFileContents := `---
+foo: bar
+`
+
+	err := os.WriteFile(configFilePath, []byte(configFileContents), 0o600)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	watcher := NewWatcher(&WatcherOpts{ErrorWriter: os.Stderr})
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	go func() {
+		err = watcher.Start(ctx)
+		if err != nil {
+			t.Errorf("failed to start watcher: %v", err)
+		}
+	}()
+
+	watcher.Watch(configFilePath)
+
+	select {
+	case <-watcher.Reload:
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("timeout waiting for initial config event")
+	}
+
+	newConfigFileContents := `---
+foo: baz
+`
+
+	err = os.WriteFile(configFilePath, []byte(newConfigFileContents), 0o600)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	select {
+	case <-watcher.Reload:
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("timeout waiting for config event")
+	}
+
+	err = os.Rename(configFilePath, configFilePath+".new")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	select {
+	case <-watcher.Drop:
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("timeout waiting for config drop event")
+	}
+}