fix(cef): graceful shutdown on signal and stale singleton cleanup

- Keep signal handler registered between first and second Ctrl+C so
  GTK shutdown + CEF cleanup can complete before process exit
- Clean up stale CEF SingletonLock/Socket/Cookie files on startup
  when the owning process is dead (prevents SIGSEGV on restart)
- Guard persistTitleUpdate against empty titles

commit: 04220c184d9b33790565030876b8edf675704e52
author: brice · 7mo ago · 2026-03-20 15:41 UTC
committer: brice · 6mo ago · 2026-03-28 04:36 UTC
parent: 030c8ba
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

3 files · +62 -3

M cmd/dumber/main.go +10 -3


@@ -406,13 +406,20 @@ func handleAutoRestore(
406	406
407	407		func setupSignalHandler(ctx context.Context, app *ui.App) {
408	408		log := logging.FromContext(ctx)
409		-	sigCh := make(chan os.Signal, 1)
	409	+	sigCh := make(chan os.Signal, 2)
410	410		signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
411	411		go func() {
412	412		sig := <-sigCh
413		-	signal.Stop(sigCh)
414		-	log.Info().Str("signal", sig.String()).Msg("received interrupt, quitting")
	413	+	log.Info().Str("signal", sig.String()).Msg("received interrupt, quitting gracefully")
415	414		app.Quit()
	415	+
	416	+	// Second signal: force exit. Keep listening so a second Ctrl+C
	417	+	// doesn't go to the default handler (immediate process kill)
	418	+	// before GTK shutdown + CEF cleanup can finish.
	419	+	sig = <-sigCh
	420	+	log.Warn().Str("signal", sig.String()).Msg("received second interrupt, forcing exit")
	421	+	signal.Stop(sigCh)
	422	+	os.Exit(1)
416	423		}()
417	424		}
418	425

 func setupSignalHandler(ctx context.Context, app *ui.App) {
 	log := logging.FromContext(ctx)
-	sigCh := make(chan os.Signal, 1)
+	sigCh := make(chan os.Signal, 2)
 	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
 	go func() {
 		sig := <-sigCh
-		signal.Stop(sigCh)
+		log.Info().Str("signal", sig.String()).Msg("received interrupt, quitting gracefully")
-		log.Info().Str("signal", sig.String()).Msg("received interrupt, quitting")
 		app.Quit()
+		// Second signal: force exit. Keep listening so a second Ctrl+C
+		// doesn't go to the default handler (immediate process kill)
+		// before GTK shutdown + CEF cleanup can finish.
+		sig = <-sigCh
+		log.Warn().Str("signal", sig.String()).Msg("received second interrupt, forcing exit")
+		signal.Stop(sigCh)
+		os.Exit(1)
 	}()
 }

M internal/application/usecase/navigate.go +1 -0


@@ -241,6 +241,7 @@ func (uc *NavigateUseCase) historyWorker() {
241	241		}
242	242
243	243		flushPending := func() {
	244	+
244	245		for historyURL, visits := range pendingVisits {
245	246		uc.persistHistory(uc.ctx, historyRecord{url: historyURL, visits: visits})
246	247		}


@@ -241,6 +241,7 @@ func (uc *NavigateUseCase) historyWorker() {
241	}	241		}
242		242
243	flushPending := func() {	243		flushPending := func() {
		244	+
244	for historyURL, visits := range pendingVisits {	245		for historyURL, visits := range pendingVisits {
245	uc.persistHistory(uc.ctx, historyRecord{url: historyURL, visits: visits})	246		uc.persistHistory(uc.ctx, historyRecord{url: historyURL, visits: visits})
246	}	247		}

M internal/infrastructure/cef/engine_init.go +51 -0


@@ -5,8 +5,12 @@ import (
5	5		"fmt"
6	6		"os"
7	7		"path/filepath"
	8	+	"strconv"
	9	+	"strings"
	10	+	"syscall"
8	11
9	12		purecef "github.com/bnema/purego-cef/cef"
	13	+	"github.com/rs/zerolog"
10	14
11	15		"github.com/bnema/dumber/internal/infrastructure/config"
12	16		"github.com/bnema/dumber/internal/logging"

@@ -16,6 +20,11 @@ import (
16	20		func NewEngine(ctx context.Context, cfg config.CEFEngineConfig) (*Engine, error) {
17	21		logger := logging.FromContext(ctx)
18	22
	23	+	// Clean up stale CEF singleton locks from previous unclean shutdowns.
	24	+	// When the process is killed (Ctrl+C, SIGSEGV), CEF leaves SingletonLock
	25	+	// files that cause the next instance to crash on startup.
	26	+	cleanStaleSingletonLocks(logger)
	27	+
19	28		// Resolve pump mode from config (with defaults).
20	29		multiThreaded := cfg.CEFMultiThreadedMessageLoop()
21	30		manualPumpMs := cfg.CEFManualPumpIntervalMs()

@@ -117,6 +126,48 @@ func appendIfMissing(args []string, flag string) []string {
117	126
118	127		// findHelperBinary looks for the cef-helper binary next to the running
119	128		// executable. Returns empty string if not found.
	129	+	// cleanStaleSingletonLocks removes CEF's SingletonLock/Socket/Cookie files
	130	+	// if the owning process is no longer running. CEF leaves these behind on
	131	+	// unclean shutdown (SIGKILL, SIGSEGV) and the next instance crashes trying
	132	+	// to connect to the dead process.
	133	+	func cleanStaleSingletonLocks(logger *zerolog.Logger) {
	134	+	// CEF defaults to ~/.config/cef_user_data when no root_cache_path is set.
	135	+	dir := filepath.Join(os.Getenv("HOME"), ".config", "cef_user_data")
	136	+
	137	+	lockPath := filepath.Join(dir, "SingletonLock")
	138	+	target, err := os.Readlink(lockPath)
	139	+	if err != nil {
	140	+	return // No lock file or not a symlink — nothing to clean.
	141	+	}
	142	+
	143	+	// SingletonLock is a symlink to "hostname-pid".
	144	+	parts := strings.SplitN(target, "-", 2)
	145	+	if len(parts) != 2 {
	146	+	return
	147	+	}
	148	+	pid, err := strconv.Atoi(parts[1])
	149	+	if err != nil \|\| pid <= 0 {
	150	+	return
	151	+	}
	152	+
	153	+	// Check if the process is still alive.
	154	+	proc, err := os.FindProcess(pid)
	155	+	if err == nil {
	156	+	if err := proc.Signal(syscall.Signal(0)); err == nil {
	157	+	// Process is alive — don't touch the lock.
	158	+	return
	159	+	}
	160	+	}
	161	+
	162	+	// Stale lock — remove singleton files.
	163	+	for _, name := range []string{"SingletonLock", "SingletonSocket", "SingletonCookie"} {
	164	+	p := filepath.Join(dir, name)
	165	+	if err := os.Remove(p); err == nil {
	166	+	logger.Info().Str("path", p).Msg("cef: removed stale singleton file")
	167	+	}
	168	+	}
	169	+	}
	170	+
120	171		func findHelperBinary() string {
121	172		exe, err := os.Executable()
122	173		if err != nil {


@@ -5,8 +5,12 @@ import (
5	"fmt"	5		"fmt"
6	"os"	6		"os"
7	"path/filepath"	7		"path/filepath"
		8	+	"strconv"
		9	+	"strings"
		10	+	"syscall"
8		11
9	purecef "github.com/bnema/purego-cef/cef"	12		purecef "github.com/bnema/purego-cef/cef"
		13	+	"github.com/rs/zerolog"
10		14
11	"github.com/bnema/dumber/internal/infrastructure/config"	15		"github.com/bnema/dumber/internal/infrastructure/config"
12	"github.com/bnema/dumber/internal/logging"	16		"github.com/bnema/dumber/internal/logging"

@@ -16,6 +20,11 @@ import (
16	func NewEngine(ctx context.Context, cfg config.CEFEngineConfig) (*Engine, error) {	20		func NewEngine(ctx context.Context, cfg config.CEFEngineConfig) (*Engine, error) {
17	logger := logging.FromContext(ctx)	21		logger := logging.FromContext(ctx)
18		22
		23	+	// Clean up stale CEF singleton locks from previous unclean shutdowns.
		24	+	// When the process is killed (Ctrl+C, SIGSEGV), CEF leaves SingletonLock
		25	+	// files that cause the next instance to crash on startup.
		26	+	cleanStaleSingletonLocks(logger)
		27	+
19	// Resolve pump mode from config (with defaults).	28		// Resolve pump mode from config (with defaults).
20	multiThreaded := cfg.CEFMultiThreadedMessageLoop()	29		multiThreaded := cfg.CEFMultiThreadedMessageLoop()
21	manualPumpMs := cfg.CEFManualPumpIntervalMs()	30		manualPumpMs := cfg.CEFManualPumpIntervalMs()

@@ -117,6 +126,48 @@ func appendIfMissing(args []string, flag string) []string {
117		126
118	// findHelperBinary looks for the cef-helper binary next to the running	127		// findHelperBinary looks for the cef-helper binary next to the running
119	// executable. Returns empty string if not found.	128		// executable. Returns empty string if not found.
		129	+	// cleanStaleSingletonLocks removes CEF's SingletonLock/Socket/Cookie files
		130	+	// if the owning process is no longer running. CEF leaves these behind on
		131	+	// unclean shutdown (SIGKILL, SIGSEGV) and the next instance crashes trying
		132	+	// to connect to the dead process.
		133	+	func cleanStaleSingletonLocks(logger *zerolog.Logger) {
		134	+	// CEF defaults to ~/.config/cef_user_data when no root_cache_path is set.
		135	+	dir := filepath.Join(os.Getenv("HOME"), ".config", "cef_user_data")
		136	+
		137	+	lockPath := filepath.Join(dir, "SingletonLock")
		138	+	target, err := os.Readlink(lockPath)
		139	+	if err != nil {
		140	+	return // No lock file or not a symlink — nothing to clean.
		141	+	}
		142	+
		143	+	// SingletonLock is a symlink to "hostname-pid".
		144	+	parts := strings.SplitN(target, "-", 2)
		145	+	if len(parts) != 2 {
		146	+	return
		147	+	}
		148	+	pid, err := strconv.Atoi(parts[1])
		149	+	if err != nil \|\| pid <= 0 {
		150	+	return
		151	+	}
		152	+
		153	+	// Check if the process is still alive.
		154	+	proc, err := os.FindProcess(pid)
		155	+	if err == nil {
		156	+	if err := proc.Signal(syscall.Signal(0)); err == nil {
		157	+	// Process is alive — don't touch the lock.
		158	+	return
		159	+	}
		160	+	}
		161	+
		162	+	// Stale lock — remove singleton files.
		163	+	for _, name := range []string{"SingletonLock", "SingletonSocket", "SingletonCookie"} {
		164	+	p := filepath.Join(dir, name)
		165	+	if err := os.Remove(p); err == nil {
		166	+	logger.Info().Str("path", p).Msg("cef: removed stale singleton file")
		167	+	}
		168	+	}
		169	+	}
		170	+
120	func findHelperBinary() string {	171		func findHelperBinary() string {
121	exe, err := os.Executable()	172		exe, err := os.Executable()
122	if err != nil {	173		if err != nil {