Exit LSP process if parent process stops existing

cmd/tsgo/lsp.go

@@ -1,10 +1,14 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"fmt"
 	"os"
+	"os/signal"
 	"runtime"
+	"syscall"
+	"time"
 
 	"github.com/microsoft/typescript-go/internal/bundled"
 	"github.com/microsoft/typescript-go/internal/core"
@@ -41,6 +45,9 @@ func runLSP(args []string) int {
 	defaultLibraryPath := bundled.LibPath()
 	typingsLocation := getGlobalTypingsCacheLocation()
 
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+
 	s := lsp.NewServer(&lsp.ServerOptions{
 		In:                 os.Stdin,
 		Out:                os.Stdout,
@@ -49,9 +56,27 @@ func runLSP(args []string) int {
 		FS:                 fs,
 		DefaultLibraryPath: defaultLibraryPath,
 		TypingsLocation:    typingsLocation,
+		SetParentPID: func(pid int) {
+			go func() {
+				for {
+					select {
+					case <-ctx.Done():
+						return
+					case <-time.After(10 * time.Second):
+						p, err := os.FindProcess(pid)
+						if err != nil {
+							os.Exit(1)
+						}
+						if p.Signal(syscall.Signal(0)) != nil {
+							os.Exit(1)
+						}
+					}
+				}
+			}()
+		},
 	})
 
-	if err := s.Run(); err != nil {
+	if err := s.Run(ctx); err != nil {
 		return 1
 	}
 	return 0

internal/lsp/server.go

@@ -6,12 +6,9 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"os"
-	"os/signal"
 	"runtime/debug"
 	"slices"
 	"sync"
-	"syscall"
 
 	"github.com/microsoft/typescript-go/internal/core"
 	"github.com/microsoft/typescript-go/internal/ls"
@@ -31,6 +28,8 @@ type ServerOptions struct {
 	FS                 vfs.FS
 	DefaultLibraryPath string
 	TypingsLocation    string
+
+	SetParentPID func(pid int)
 }
 
 func NewServer(opts *ServerOptions) *Server {
@@ -50,6 +49,7 @@ func NewServer(opts *ServerOptions) *Server {
 		fs:                    opts.FS,
 		defaultLibraryPath:    opts.DefaultLibraryPath,
 		typingsLocation:       opts.TypingsLocation,
+		setParentPID:          opts.SetParentPID,
 	}
 }
 
@@ -83,6 +83,8 @@ type Server struct {
 	defaultLibraryPath string
 	typingsLocation    string
 
+	setParentPID func(pid int)
+
 	initializeParams *lsproto.InitializeParams
 	positionEncoding lsproto.PositionEncodingKind
 
@@ -187,10 +189,7 @@ func (s *Server) RefreshDiagnostics(ctx context.Context) error {
 	return nil
 }
 
-func (s *Server) Run() error {
-	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
-	defer stop()
-
+func (s *Server) Run(ctx context.Context) error {
 	g, ctx := errgroup.WithContext(ctx)
 	g.Go(func() error { return s.dispatchLoop(ctx) })
 	g.Go(func() error { return s.writeLoop(ctx) })
@@ -452,6 +451,12 @@ func (s *Server) handleRequestOrNotification(ctx context.Context, req *lsproto.R
 func (s *Server) handleInitialize(req *lsproto.RequestMessage) {
 	s.initializeParams = req.Params.(*lsproto.InitializeParams)
 
+	if s.setParentPID != nil {
+		if pid := s.initializeParams.ProcessId.Value; pid != 0 {
+			s.setParentPID(int(pid))
+		}
+	}
+
 	s.positionEncoding = lsproto.PositionEncodingKindUTF16
 	if genCapabilities := s.initializeParams.Capabilities.General; genCapabilities != nil && genCapabilities.PositionEncodings != nil {
 		if slices.Contains(*genCapabilities.PositionEncodings, lsproto.PositionEncodingKindUTF8) {