progress: extract progress updating into Updater struct

This allows reusing the code to create periodic progress updates.

cmd/restic/progress.go

@@ -37,7 +37,7 @@ func newProgressMax(show bool, max uint64, description string) *progress.Counter
 	interval := calculateProgressInterval(show, false)
 	canUpdateStatus := stdoutCanUpdateStatus()
 
-	return progress.New(interval, max, func(v uint64, max uint64, d time.Duration, final bool) {
+	return progress.NewCounter(interval, max, func(v uint64, max uint64, d time.Duration, final bool) {
 		var status string
 		if max == 0 {
 			status = fmt.Sprintf("[%s]          %d %s",

internal/restic/find_test.go

@@ -93,7 +93,7 @@ func TestFindUsedBlobs(t *testing.T) {
 		snapshots = append(snapshots, sn)
 	}
 
-	p := progress.New(time.Second, findTestSnapshots, func(value uint64, total uint64, runtime time.Duration, final bool) {})
+	p := progress.NewCounter(time.Second, findTestSnapshots, func(value uint64, total uint64, runtime time.Duration, final bool) {})
 	defer p.Done()
 
 	for i, sn := range snapshots {
@@ -142,7 +142,7 @@ func TestMultiFindUsedBlobs(t *testing.T) {
 		want.Merge(loadIDSet(t, goldenFilename))
 	}
 
-	p := progress.New(time.Second, findTestSnapshots, func(value uint64, total uint64, runtime time.Duration, final bool) {})
+	p := progress.NewCounter(time.Second, findTestSnapshots, func(value uint64, total uint64, runtime time.Duration, final bool) {})
 	defer p.Done()
 
 	// run twice to check progress bar handling of duplicate tree roots

internal/ui/progress/counter.go

@@ -3,9 +3,6 @@ package progress
 import (
 	"sync"
 	"time"
-
-	"github.com/restic/restic/internal/debug"
-	"github.com/restic/restic/internal/ui/signals"
 )
 
 // A Func is a callback for a Counter.
@@ -19,32 +16,22 @@ type Func func(value uint64, total uint64, runtime time.Duration, final bool)
 //
 // The Func is also called when SIGUSR1 (or SIGINFO, on BSD) is received.
 type Counter struct {
-	report  Func
-	start   time.Time
-	stopped chan struct{} // Closed by run.
-	stop    chan struct{} // Close to stop run.
-	tick    *time.Ticker
+	Updater
 
 	valueMutex sync.Mutex
 	value      uint64
 	max        uint64
 }
 
-// New starts a new Counter.
-func New(interval time.Duration, total uint64, report Func) *Counter {
+// NewCounter starts a new Counter.
+func NewCounter(interval time.Duration, total uint64, report Func) *Counter {
 	c := &Counter{
-		report:  report,
-		start:   time.Now(),
-		stopped: make(chan struct{}),
-		stop:    make(chan struct{}),
-		max:     total,
+		max: total,
 	}
-
-	if interval > 0 {
-		c.tick = time.NewTicker(interval)
-	}
-
-	go c.run()
+	c.Updater = *NewUpdater(interval, func(runtime time.Duration, final bool) {
+		v, max := c.Get()
+		report(v, max, runtime, final)
+	})
 	return c
 }
 
@@ -69,18 +56,6 @@ func (c *Counter) SetMax(max uint64) {
 	c.valueMutex.Unlock()
 }
 
-// Done tells a Counter to stop and waits for it to report its final value.
-func (c *Counter) Done() {
-	if c == nil {
-		return
-	}
-	if c.tick != nil {
-		c.tick.Stop()
-	}
-	close(c.stop)
-	<-c.stopped // Wait for last progress report.
-}
-
 // Get returns the current value and the maximum of c.
 // This method is concurrency-safe.
 func (c *Counter) Get() (v, max uint64) {
@@ -91,32 +66,8 @@ func (c *Counter) Get() (v, max uint64) {
 	return v, max
 }
 
-func (c *Counter) run() {
-	defer close(c.stopped)
-	defer func() {
-		// Must be a func so that time.Since isn't called at defer time.
-		v, max := c.Get()
-		c.report(v, max, time.Since(c.start), true)
-	}()
-
-	var tick <-chan time.Time
-	if c.tick != nil {
-		tick = c.tick.C
-	}
-	signalsCh := signals.GetProgressChannel()
-	for {
-		var now time.Time
-
-		select {
-		case now = <-tick:
-		case sig := <-signalsCh:
-			debug.Log("Signal received: %v\n", sig)
-			now = time.Now()
-		case <-c.stop:
-			return
-		}
-
-		v, max := c.Get()
-		c.report(v, max, now.Sub(c.start), false)
+func (c *Counter) Done() {
+	if c != nil {
+		c.Updater.Done()
 	}
 }

internal/ui/progress/counter_test.go

@@ -35,7 +35,7 @@ func TestCounter(t *testing.T) {
 		lastTotal = total
 		ncalls++
 	}
-	c := progress.New(10*time.Millisecond, startTotal, report)
+	c := progress.NewCounter(10*time.Millisecond, startTotal, report)
 
 	done := make(chan struct{})
 	go func() {
@@ -63,24 +63,6 @@ func TestCounterNil(t *testing.T) {
 	// Shouldn't panic.
 	var c *progress.Counter
 	c.Add(1)
+	c.SetMax(42)
 	c.Done()
 }
-
-func TestCounterNoTick(t *testing.T) {
-	finalSeen := false
-	otherSeen := false
-
-	report := func(value, total uint64, d time.Duration, final bool) {
-		if final {
-			finalSeen = true
-		} else {
-			otherSeen = true
-		}
-	}
-	c := progress.New(0, 1, report)
-	time.Sleep(time.Millisecond)
-	c.Done()
-
-	test.Assert(t, finalSeen, "final call did not happen")
-	test.Assert(t, !otherSeen, "unexpected status update")
-}

internal/ui/progress/updater.go

@@ -0,0 +1,84 @@
+package progress
+
+import (
+	"time"
+
+	"github.com/restic/restic/internal/debug"
+	"github.com/restic/restic/internal/ui/signals"
+)
+
+// An UpdateFunc is a callback for a (progress) Updater.
+//
+// The final argument is true if Updater.Done has been called,
+// which means that the current call will be the last.
+type UpdateFunc func(runtime time.Duration, final bool)
+
+// An Updater controls a goroutine that periodically calls an UpdateFunc.
+//
+// The UpdateFunc is also called when SIGUSR1 (or SIGINFO, on BSD) is received.
+type Updater struct {
+	report  UpdateFunc
+	start   time.Time
+	stopped chan struct{} // Closed by run.
+	stop    chan struct{} // Close to stop run.
+	tick    *time.Ticker
+}
+
+// NewUpdater starts a new Updater.
+func NewUpdater(interval time.Duration, report UpdateFunc) *Updater {
+	c := &Updater{
+		report:  report,
+		start:   time.Now(),
+		stopped: make(chan struct{}),
+		stop:    make(chan struct{}),
+	}
+
+	if interval > 0 {
+		c.tick = time.NewTicker(interval)
+	}
+
+	go c.run()
+	return c
+}
+
+// Done tells an Updater to stop and waits for it to report its final value.
+// Later calls do nothing.
+func (c *Updater) Done() {
+	if c == nil || c.stop == nil {
+		return
+	}
+	if c.tick != nil {
+		c.tick.Stop()
+	}
+	close(c.stop)
+	<-c.stopped // Wait for last progress report.
+	c.stop = nil
+}
+
+func (c *Updater) run() {
+	defer close(c.stopped)
+	defer func() {
+		// Must be a func so that time.Since isn't called at defer time.
+		c.report(time.Since(c.start), true)
+	}()
+
+	var tick <-chan time.Time
+	if c.tick != nil {
+		tick = c.tick.C
+	}
+	signalsCh := signals.GetProgressChannel()
+	for {
+		var now time.Time
+
+		select {
+		case now = <-tick:
+		case sig := <-signalsCh:
+			debug.Log("Signal received: %v\n", sig)
+			now = time.Now()
+		case <-c.stop:
+			return
+		}
+
+		c.report(now.Sub(c.start), false)
+	}
+}

internal/ui/progress/updater_test.go

@@ -0,0 +1,52 @@
+package progress_test
+
+import (
+	"testing"
+	"time"
+
+	"github.com/restic/restic/internal/test"
+	"github.com/restic/restic/internal/ui/progress"
+)
+
+func TestUpdater(t *testing.T) {
+	finalSeen := false
+	var ncalls int
+
+	report := func(d time.Duration, final bool) {
+		if final {
+			finalSeen = true
+		}
+		ncalls++
+	}
+	c := progress.NewUpdater(10*time.Millisecond, report)
+	time.Sleep(100 * time.Millisecond)
+	c.Done()
+
+	test.Assert(t, finalSeen, "final call did not happen")
+	test.Assert(t, ncalls > 0, "no progress was reported")
+}
+
+func TestUpdaterStopTwice(t *testing.T) {
+	c := progress.NewUpdater(0, func(runtime time.Duration, final bool) {})
+	c.Done()
+	c.Done()
+}
+
+func TestUpdaterNoTick(t *testing.T) {
+	finalSeen := false
+	otherSeen := false
+
+	report := func(d time.Duration, final bool) {
+		if final {
+			finalSeen = true
+		} else {
+			otherSeen = true
+		}
+	}
+	c := progress.NewUpdater(0, report)
+	time.Sleep(time.Millisecond)
+	c.Done()
+
+	test.Assert(t, finalSeen, "final call did not happen")
+	test.Assert(t, !otherSeen, "unexpected status update")
+}