feat(module): count script starts with Gen

commit: 718054e7612e0f188e5123cccffa59c81f3e2074
author: brice · 13d ago · 2026-10-09 03:59 UTC
parent: 3c1ce2c
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +32 -1

M internal/module/module.go +9 -1


@@ -15,6 +15,7 @@ import (
15	15		"path/filepath"
16	16		"strings"
17	17		"sync"
	18	+	"sync/atomic"
18	19		"syscall"
19	20		"time"
20	21		)

@@ -55,7 +56,8 @@ type Module struct {
55	56		dirty bool
56	57		failed bool // the script is not running; show an error marker
57	58
58		-	input chan event // lines for the script's stdin
	59	+	input chan event // lines for the script's stdin
	60	+	gen atomic.Uint64 // counts script starts; see Gen
59	61
60	62		wake chan<- struct{}
61	63		log *slog.Logger

@@ -78,6 +80,11 @@ func New(name string, zone Zone, command string, wake chan<- struct{}, log *slog
78	80		pending: make([]byte, 0, MaxFrame), input: make(chan event, 32)}
79	81		}
80	82
	83	+	// Gen counts the times the script was started. A value that changed means a
	84	+	// new process, which knows nothing of the pointer state sent to the old one.
	85	+	// It does not allocate.
	86	+	func (m *Module) Gen() uint64 { return m.gen.Load() }
	87	+
81	88		// Send queues line (without a newline) for the script's stdin. It never
82	89		// blocks and does not allocate. It reports false when the module is not
83	90		// interactive, the line is longer than 127 bytes, or 32 lines are already

@@ -181,6 +188,7 @@ func (m *Module) Run(ctx context.Context) {
181	188		}
182	189
183	190		func (m *Module) runOnce(ctx context.Context) error {
	191	+	m.gen.Add(1)
184	192		cmd := exec.CommandContext(ctx, "/bin/sh", "-c", m.Exec)
185	193		cmd.Stderr = &logWriter{log: m.log, name: m.Name}
186	194		cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true, Pdeathsig: syscall.SIGTERM}

 	"path/filepath"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"time"
 )
 	dirty   bool
 	failed  bool // the script is not running; show an error marker
-	input chan event // lines for the script's stdin
+	input chan event    // lines for the script's stdin
+	gen   atomic.Uint64 // counts script starts; see Gen
 	wake chan<- struct{}
 	log  *slog.Logger
 		pending: make([]byte, 0, MaxFrame), input: make(chan event, 32)}
 }
+// Gen counts the times the script was started. A value that changed means a
+// new process, which knows nothing of the pointer state sent to the old one.
+// It does not allocate.
+func (m *Module) Gen() uint64 { return m.gen.Load() }
 // Send queues line (without a newline) for the script's stdin. It never
 // blocks and does not allocate. It reports false when the module is not
 // interactive, the line is longer than 127 bytes, or 32 lines are already
 }
 func (m *Module) runOnce(ctx context.Context) error {
+	m.gen.Add(1)
 	cmd := exec.CommandContext(ctx, "/bin/sh", "-c", m.Exec)
 	cmd.Stderr = &logWriter{log: m.log, name: m.Name}
 	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true, Pdeathsig: syscall.SIGTERM}

M internal/module/module_test.go +23 -0


@@ -226,3 +226,26 @@ func TestSendAllocs(t *testing.T) {
226	226		t.Errorf("Send allocates %.1f objects; want 0", got)
227	227		}
228	228		}
	229	+
	230	+	func TestGenCountsStarts(t *testing.T) {
	231	+	wake := make(chan struct{}, 1)
	232	+	m := New("t", Left, "printf 'hi\\n'", wake, slog.New(slog.DiscardHandler))
	233	+	if m.Gen() != 0 {
	234	+	t.Fatalf("Gen before start = %d", m.Gen())
	235	+	}
	236	+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	237	+	defer cancel()
	238	+	go m.Run(ctx)
	239	+	deadline := time.After(4 * time.Second)
	240	+	for m.Gen() < 2 { // the script exits at once and is restarted
	241	+	select {
	242	+	case <-wake:
	243	+	case <-time.After(20 * time.Millisecond):
	244	+	case <-deadline:
	245	+	t.Fatalf("Gen = %d, want at least 2 after a restart", m.Gen())
	246	+	}
	247	+	}
	248	+	if allocs := testing.AllocsPerRun(100, func() { m.Gen() }); allocs != 0 {
	249	+	t.Errorf("Gen allocates %v", allocs)
	250	+	}
	251	+	}


@@ -226,3 +226,26 @@ func TestSendAllocs(t *testing.T) {
226	t.Errorf("Send allocates %.1f objects; want 0", got)	226		t.Errorf("Send allocates %.1f objects; want 0", got)
227	}	227		}
228	}	228		}
		229	+
		230	+	func TestGenCountsStarts(t *testing.T) {
		231	+	wake := make(chan struct{}, 1)
		232	+	m := New("t", Left, "printf 'hi\\n'", wake, slog.New(slog.DiscardHandler))
		233	+	if m.Gen() != 0 {
		234	+	t.Fatalf("Gen before start = %d", m.Gen())
		235	+	}
		236	+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
		237	+	defer cancel()
		238	+	go m.Run(ctx)
		239	+	deadline := time.After(4 * time.Second)
		240	+	for m.Gen() < 2 { // the script exits at once and is restarted
		241	+	select {
		242	+	case <-wake:
		243	+	case <-time.After(20 * time.Millisecond):
		244	+	case <-deadline:
		245	+	t.Fatalf("Gen = %d, want at least 2 after a restart", m.Gen())
		246	+	}
		247	+	}
		248	+	if allocs := testing.AllocsPerRun(100, func() { m.Gen() }); allocs != 0 {
		249	+	t.Errorf("Gen allocates %v", allocs)
		250	+	}
		251	+	}