Fix calls to repo/backend.List() everywhere

internal/checker/checker.go

@@ -12,6 +12,7 @@ import (
 	"github.com/restic/restic/internal/fs"
 	"github.com/restic/restic/internal/hashing"
 	"github.com/restic/restic/internal/restic"
+	"golang.org/x/sync/errgroup"
 
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/pack"
@@ -192,13 +193,14 @@ func (c *Checker) Packs(ctx context.Context, errChan chan<- error) {
 
 	debug.Log("listing repository packs")
 	repoPacks := restic.NewIDSet()
-	for id := range c.repo.List(ctx, restic.DataFile) {
-		select {
-		case <-ctx.Done():
-			return
-		default:
-		}
+
+	err := c.repo.List(ctx, restic.DataFile, func(id restic.ID, size int64) error {
 		repoPacks.Insert(id)
+		return nil
+	})
+
+	if err != nil {
+		errChan <- err
 	}
 
 	// orphaned: present in the repo but not in c.packs
@@ -719,42 +721,58 @@ func (c *Checker) ReadData(ctx context.Context, p *restic.Progress, errChan chan
 	p.Start()
 	defer p.Done()
 
-	worker := func(wg *sync.WaitGroup, in <-chan restic.ID) {
-		defer wg.Done()
-		for {
-			var id restic.ID
-			var ok bool
+	g, ctx := errgroup.WithContext(ctx)
+	ch := make(chan restic.ID)
 
+	// start producer for channel ch
+	g.Go(func() error {
+		defer close(ch)
+		return c.repo.List(ctx, restic.DataFile, func(id restic.ID, size int64) error {
 			select {
 			case <-ctx.Done():
-				return
-			case id, ok = <-in:
-				if !ok {
-					return
+			case ch <- id:
+			}
+			return nil
+		})
+	})
+
+	// run workers
+	for i := 0; i < defaultParallelism; i++ {
+		g.Go(func() error {
+			for {
+				var id restic.ID
+				var ok bool
+
+				select {
+				case <-ctx.Done():
+					return nil
+				case id, ok = <-ch:
+					if !ok {
+						return nil
+					}
+				}
+
+				err := checkPack(ctx, c.repo, id)
+				p.Report(restic.Stat{Blobs: 1})
+				if err == nil {
+					continue
+				}
+
+				select {
+				case <-ctx.Done():
+					return nil
+				case errChan <- err:
 				}
 			}
+		})
+	}
 
-			err := checkPack(ctx, c.repo, id)
-			p.Report(restic.Stat{Blobs: 1})
-			if err == nil {
-				continue
-			}
-
-			select {
-			case <-ctx.Done():
-				return
-			case errChan <- err:
-			}
+	err := g.Wait()
+	if err != nil {
+		select {
+		case <-ctx.Done():
+			return
+		case errChan <- err:
 		}
 	}
-
-	ch := c.repo.List(ctx, restic.DataFile)
-
-	var wg sync.WaitGroup
-	for i := 0; i < defaultParallelism; i++ {
-		wg.Add(1)
-		go worker(&wg, ch)
-	}
-
-	wg.Wait()
 }