Merge pull request #5532 from MichaelEischer/checker-cleanup

Replace Repository.SetIndex with internal helper

cmd/restic/cmd_check.go

@@ -257,10 +257,10 @@ func runCheck(ctx context.Context, opts CheckOptions, gopts GlobalOptions, args
 	errorsFound := false
 	for _, hint := range hints {
 		switch hint.(type) {
-		case *checker.ErrDuplicatePacks:
+		case *repository.ErrDuplicatePacks:
 			printer.S("%s", hint.Error())
 			summary.HintRepairIndex = true
-		case *checker.ErrMixedPack:
+		case *repository.ErrMixedPack:
 			printer.S("%s", hint.Error())
 			summary.HintPrune = true
 		default:
@@ -295,7 +295,7 @@ func runCheck(ctx context.Context, opts CheckOptions, gopts GlobalOptions, args
 	go chkr.Packs(ctx, errChan)
 
 	for err := range errChan {
-		var packErr *checker.PackError
+		var packErr *repository.PackError
 		if errors.As(err, &packErr) {
 			if packErr.Orphaned {
 				orphanedPacks++

internal/archiver/archiver_test.go

@@ -29,7 +29,7 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
-func prepareTempdirRepoSrc(t testing.TB, src TestDir) (string, restic.Repository) {
+func prepareTempdirRepoSrc(t testing.TB, src TestDir) (string, *repository.Repository) {
 	tempdir := rtest.TempDir(t)
 	repo := repository.TestRepository(t)
 
@@ -1421,7 +1421,7 @@ func TestArchiverSnapshot(t *testing.T) {
 			}
 			TestEnsureSnapshot(t, repo, snapshotID, want)
 
-			checker.TestCheckRepo(t, repo, false)
+			checker.TestCheckRepo(t, repo)
 
 			// check that the snapshot contains the targets with absolute paths
 			for i, target := range sn.Paths {
@@ -1641,7 +1641,7 @@ func TestArchiverSnapshotSelect(t *testing.T) {
 			}
 			TestEnsureSnapshot(t, repo, snapshotID, want)
 
-			checker.TestCheckRepo(t, repo, false)
+			checker.TestCheckRepo(t, repo)
 		})
 	}
 }
@@ -1866,7 +1866,7 @@ func TestArchiverParent(t *testing.T) {
 				t.Logf("testfs: %v", testFS)
 			}
 
-			checker.TestCheckRepo(t, repo, false)
+			checker.TestCheckRepo(t, repo)
 		})
 	}
 }
@@ -2021,7 +2021,7 @@ func TestArchiverErrorReporting(t *testing.T) {
 			}
 			TestEnsureSnapshot(t, repo, snapshotID, want)
 
-			checker.TestCheckRepo(t, repo, false)
+			checker.TestCheckRepo(t, repo)
 		})
 	}
 }
@@ -2384,7 +2384,7 @@ func TestMetadataChanged(t *testing.T) {
 	// make sure the content matches
 	TestEnsureFileContent(context.Background(), t, repo, "testfile", node3, files["testfile"].(TestFile))
 
-	checker.TestCheckRepo(t, repo, false)
+	checker.TestCheckRepo(t, repo)
 }
 
 func TestRacyFileTypeSwap(t *testing.T) {

internal/checker/checker.go

@@ -1,19 +1,15 @@
 package checker
 
 import (
-	"bufio"
 	"context"
 	"fmt"
 	"runtime"
 	"sync"
 
-	"github.com/klauspost/compress/zstd"
 	"github.com/restic/restic/internal/data"
 	"github.com/restic/restic/internal/debug"
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/repository"
-	"github.com/restic/restic/internal/repository/index"
-	"github.com/restic/restic/internal/repository/pack"
 	"github.com/restic/restic/internal/restic"
 	"github.com/restic/restic/internal/ui/progress"
 	"golang.org/x/sync/errgroup"
@@ -25,24 +21,27 @@ import (
 // A Checker only tests for internal errors within the data structures of the
 // repository (e.g. missing blobs), and needs a valid Repository to work on.
 type Checker struct {
-	packs    map[restic.ID]int64
+	*repository.Checker
 	blobRefs struct {
 		sync.Mutex
 		M restic.BlobSet
 	}
 	trackUnused bool
 
-	masterIndex *index.MasterIndex
-	snapshots   restic.Lister
+	snapshots restic.Lister
 
 	repo restic.Repository
 }
 
+type checkerRepository interface {
+	restic.Repository
+	Checker() *repository.Checker
+}
+
 // New returns a new checker which runs on repo.
-func New(repo restic.Repository, trackUnused bool) *Checker {
+func New(repo checkerRepository, trackUnused bool) *Checker {
 	c := &Checker{
-		packs:       make(map[restic.ID]int64),
-		masterIndex: index.NewMasterIndex(),
+		Checker:     repo.Checker(),
 		repo:        repo,
 		trackUnused: trackUnused,
 	}
@@ -52,186 +51,12 @@ func New(repo restic.Repository, trackUnused bool) *Checker {
 	return c
 }
 
-// ErrDuplicatePacks is returned when a pack is found in more than one index.
-type ErrDuplicatePacks struct {
-	PackID  restic.ID
-	Indexes restic.IDSet
-}
-
-func (e *ErrDuplicatePacks) Error() string {
-	return fmt.Sprintf("pack %v contained in several indexes: %v", e.PackID, e.Indexes)
-}
-
-// ErrMixedPack is returned when a pack is found that contains both tree and data blobs.
-type ErrMixedPack struct {
-	PackID restic.ID
-}
-
-func (e *ErrMixedPack) Error() string {
-	return fmt.Sprintf("pack %v contains a mix of tree and data blobs", e.PackID.Str())
-}
-
 func (c *Checker) LoadSnapshots(ctx context.Context) error {
 	var err error
 	c.snapshots, err = restic.MemorizeList(ctx, c.repo, restic.SnapshotFile)
 	return err
 }
 
-func computePackTypes(ctx context.Context, idx restic.ListBlobser) (map[restic.ID]restic.BlobType, error) {
-	packs := make(map[restic.ID]restic.BlobType)
-	err := idx.ListBlobs(ctx, func(pb restic.PackedBlob) {
-		tpe, exists := packs[pb.PackID]
-		if exists {
-			if pb.Type != tpe {
-				tpe = restic.InvalidBlob
-			}
-		} else {
-			tpe = pb.Type
-		}
-		packs[pb.PackID] = tpe
-	})
-	return packs, err
-}
-
-// LoadIndex loads all index files.
-func (c *Checker) LoadIndex(ctx context.Context, p restic.TerminalCounterFactory) (hints []error, errs []error) {
-	debug.Log("Start")
-
-	var bar *progress.Counter
-	if p != nil {
-		bar = p.NewCounterTerminalOnly("index files loaded")
-	}
-
-	packToIndex := make(map[restic.ID]restic.IDSet)
-	err := c.masterIndex.Load(ctx, c.repo, bar, func(id restic.ID, idx *index.Index, err error) error {
-		debug.Log("process index %v, err %v", id, err)
-		err = errors.Wrapf(err, "error loading index %v", id)
-
-		if err != nil {
-			errs = append(errs, err)
-			return nil
-		}
-
-		debug.Log("process blobs")
-		cnt := 0
-		err = idx.Each(ctx, func(blob restic.PackedBlob) {
-			cnt++
-
-			if _, ok := packToIndex[blob.PackID]; !ok {
-				packToIndex[blob.PackID] = restic.NewIDSet()
-			}
-			packToIndex[blob.PackID].Insert(id)
-		})
-
-		debug.Log("%d blobs processed", cnt)
-		return err
-	})
-	if err != nil {
-		// failed to load the index
-		return hints, append(errs, err)
-	}
-
-	err = c.repo.SetIndex(c.masterIndex)
-	if err != nil {
-		debug.Log("SetIndex returned error: %v", err)
-		errs = append(errs, err)
-	}
-
-	// compute pack size using index entries
-	c.packs, err = pack.Size(ctx, c.repo, false)
-	if err != nil {
-		return hints, append(errs, err)
-	}
-	packTypes, err := computePackTypes(ctx, c.repo)
-	if err != nil {
-		return hints, append(errs, err)
-	}
-
-	debug.Log("checking for duplicate packs")
-	for packID := range c.packs {
-		debug.Log("  check pack %v: contained in %d indexes", packID, len(packToIndex[packID]))
-		if len(packToIndex[packID]) > 1 {
-			hints = append(hints, &ErrDuplicatePacks{
-				PackID:  packID,
-				Indexes: packToIndex[packID],
-			})
-		}
-		if packTypes[packID] == restic.InvalidBlob {
-			hints = append(hints, &ErrMixedPack{
-				PackID: packID,
-			})
-		}
-	}
-
-	return hints, errs
-}
-
-// PackError describes an error with a specific pack.
-type PackError struct {
-	ID        restic.ID
-	Orphaned  bool
-	Truncated bool
-	Err       error
-}
-
-func (e *PackError) Error() string {
-	return "pack " + e.ID.String() + ": " + e.Err.Error()
-}
-
-// Packs checks that all packs referenced in the index are still available and
-// there are no packs that aren't in an index. errChan is closed after all
-// packs have been checked.
-func (c *Checker) Packs(ctx context.Context, errChan chan<- error) {
-	defer close(errChan)
-	debug.Log("checking for %d packs", len(c.packs))
-
-	debug.Log("listing repository packs")
-	repoPacks := make(map[restic.ID]int64)
-
-	err := c.repo.List(ctx, restic.PackFile, func(id restic.ID, size int64) error {
-		repoPacks[id] = size
-		return nil
-	})
-
-	if err != nil {
-		errChan <- err
-	}
-
-	for id, size := range c.packs {
-		reposize, ok := repoPacks[id]
-		// remove from repoPacks so we can find orphaned packs
-		delete(repoPacks, id)
-
-		// missing: present in c.packs but not in the repo
-		if !ok {
-			select {
-			case <-ctx.Done():
-				return
-			case errChan <- &PackError{ID: id, Err: errors.New("does not exist")}:
-			}
-			continue
-		}
-
-		// size not matching: present in c.packs and in the repo, but sizes do not match
-		if size != reposize {
-			select {
-			case <-ctx.Done():
-				return
-			case errChan <- &PackError{ID: id, Truncated: true, Err: errors.Errorf("unexpected file size: got %d, expected %d", reposize, size)}:
-			}
-		}
-	}
-
-	// orphaned: present in the repo but not in c.packs
-	for orphanID := range repoPacks {
-		select {
-		case <-ctx.Done():
-			return
-		case errChan <- &PackError{ID: orphanID, Orphaned: true, Err: errors.New("not referenced in any index")}:
-		}
-	}
-}
-
 // Error is an error that occurred while checking a repository.
 type Error struct {
 	TreeID restic.ID
@@ -434,97 +259,3 @@ func (c *Checker) UnusedBlobs(ctx context.Context) (blobs restic.BlobHandles, er
 
 	return blobs, err
 }
-
-// CountPacks returns the number of packs in the repository.
-func (c *Checker) CountPacks() uint64 {
-	return uint64(len(c.packs))
-}
-
-// GetPacks returns IDSet of packs in the repository
-func (c *Checker) GetPacks() map[restic.ID]int64 {
-	return c.packs
-}
-
-// ReadData loads all data from the repository and checks the integrity.
-func (c *Checker) ReadData(ctx context.Context, errChan chan<- error) {
-	c.ReadPacks(ctx, c.packs, nil, errChan)
-}
-
-const maxStreamBufferSize = 4 * 1024 * 1024
-
-// ReadPacks loads data from specified packs and checks the integrity.
-func (c *Checker) ReadPacks(ctx context.Context, packs map[restic.ID]int64, p *progress.Counter, errChan chan<- error) {
-	defer close(errChan)
-
-	g, ctx := errgroup.WithContext(ctx)
-	type checkTask struct {
-		id    restic.ID
-		size  int64
-		blobs []restic.Blob
-	}
-	ch := make(chan checkTask)
-
-	// as packs are streamed the concurrency is limited by IO
-	workerCount := int(c.repo.Connections())
-	// run workers
-	for i := 0; i < workerCount; i++ {
-		g.Go(func() error {
-			bufRd := bufio.NewReaderSize(nil, maxStreamBufferSize)
-			dec, err := zstd.NewReader(nil)
-			if err != nil {
-				panic(dec)
-			}
-			defer dec.Close()
-			for {
-				var ps checkTask
-				var ok bool
-
-				select {
-				case <-ctx.Done():
-					return nil
-				case ps, ok = <-ch:
-					if !ok {
-						return nil
-					}
-				}
-
-				err := repository.CheckPack(ctx, c.repo.(*repository.Repository), ps.id, ps.blobs, ps.size, bufRd, dec)
-				p.Add(1)
-				if err == nil {
-					continue
-				}
-
-				select {
-				case <-ctx.Done():
-					return nil
-				case errChan <- err:
-				}
-			}
-		})
-	}
-
-	packSet := restic.NewIDSet()
-	for pack := range packs {
-		packSet.Insert(pack)
-	}
-
-	// push packs to ch
-	for pbs := range c.repo.ListPacksFromIndex(ctx, packSet) {
-		size := packs[pbs.PackID]
-		debug.Log("listed %v", pbs.PackID)
-		select {
-		case ch <- checkTask{id: pbs.PackID, size: size, blobs: pbs.Blobs}:
-		case <-ctx.Done():
-		}
-	}
-	close(ch)
-
-	err := g.Wait()
-	if err != nil {
-		select {
-		case <-ctx.Done():
-			return
-		case errChan <- err:
-		}
-	}
-}

internal/checker/checker_test.go

@@ -67,7 +67,7 @@ func checkData(chkr *checker.Checker) []error {
 
 func assertOnlyMixedPackHints(t *testing.T, hints []error) {
 	for _, err := range hints {
-		if _, ok := err.(*checker.ErrMixedPack); !ok {
+		if _, ok := err.(*repository.ErrMixedPack); !ok {
 			t.Fatalf("expected mixed pack hint, got %v", err)
 		}
 	}
@@ -110,7 +110,7 @@ func TestMissingPack(t *testing.T) {
 	test.Assert(t, len(errs) == 1,
 		"expected exactly one error, got %v", len(errs))
 
-	if err, ok := errs[0].(*checker.PackError); ok {
+	if err, ok := errs[0].(*repository.PackError); ok {
 		test.Equals(t, packID, err.ID)
 	} else {
 		t.Errorf("expected error returned by checker.Packs() to be PackError, got %v", err)
@@ -138,7 +138,7 @@ func TestUnreferencedPack(t *testing.T) {
 	test.Assert(t, len(errs) == 1,
 		"expected exactly one error, got %v", len(errs))
 
-	if err, ok := errs[0].(*checker.PackError); ok {
+	if err, ok := errs[0].(*repository.PackError); ok {
 		test.Equals(t, packID, err.ID.String())
 	} else {
 		t.Errorf("expected error returned by checker.Packs() to be PackError, got %v", err)
@@ -269,7 +269,7 @@ func TestDuplicatePacksInIndex(t *testing.T) {
 
 	found := false
 	for _, hint := range hints {
-		if _, ok := hint.(*checker.ErrDuplicatePacks); ok {
+		if _, ok := hint.(*repository.ErrDuplicatePacks); ok {
 			found = true
 		} else {
 			t.Errorf("got unexpected hint: %v", hint)
@@ -435,13 +435,16 @@ func TestCheckerModifiedData(t *testing.T) {
 
 // loadTreesOnceRepository allows each tree to be loaded only once
 type loadTreesOnceRepository struct {
-	restic.Repository
+	*repository.Repository
 	loadedTrees   restic.IDSet
 	mutex         sync.Mutex
 	DuplicateTree bool
 }
 
-func (r *loadTreesOnceRepository) LoadTree(ctx context.Context, id restic.ID) (*data.Tree, error) {
+func (r *loadTreesOnceRepository) LoadBlob(ctx context.Context, t restic.BlobType, id restic.ID, buf []byte) ([]byte, error) {
+	if t != restic.TreeBlob {
+		return r.Repository.LoadBlob(ctx, t, id, buf)
+	}
 	r.mutex.Lock()
 	defer r.mutex.Unlock()
 
@@ -451,7 +454,7 @@ func (r *loadTreesOnceRepository) LoadTree(ctx context.Context, id restic.ID) (*
 		return nil, errors.Errorf("trying to load tree with id %v twice", id)
 	}
 	r.loadedTrees.Insert(id)
-	return data.LoadTree(ctx, r.Repository, id)
+	return r.Repository.LoadBlob(ctx, t, id, buf)
 }
 
 func TestCheckerNoDuplicateTreeDecodes(t *testing.T) {
@@ -471,22 +474,24 @@ func TestCheckerNoDuplicateTreeDecodes(t *testing.T) {
 
 	test.OKs(t, checkPacks(chkr))
 	test.OKs(t, checkStruct(chkr))
+	test.Assert(t, len(checkRepo.loadedTrees) > 0, "intercepting tree loading did not work")
 	test.Assert(t, !checkRepo.DuplicateTree, "detected duplicate tree loading")
 }
 
 // delayRepository delays read of a specific handle.
 type delayRepository struct {
-	restic.Repository
+	*repository.Repository
 	DelayTree      restic.ID
 	UnblockChannel chan struct{}
 	Unblocker      sync.Once
+	Triggered      bool
 }
 
-func (r *delayRepository) LoadTree(ctx context.Context, id restic.ID) (*data.Tree, error) {
-	if id == r.DelayTree {
+func (r *delayRepository) LoadBlob(ctx context.Context, t restic.BlobType, id restic.ID, buf []byte) ([]byte, error) {
+	if t == restic.TreeBlob && id == r.DelayTree {
 		<-r.UnblockChannel
 	}
-	return data.LoadTree(ctx, r.Repository, id)
+	return r.Repository.LoadBlob(ctx, t, id, buf)
 }
 
 func (r *delayRepository) LookupBlobSize(t restic.BlobType, id restic.ID) (uint, bool) {
@@ -499,6 +504,7 @@ func (r *delayRepository) LookupBlobSize(t restic.BlobType, id restic.ID) (uint,
 func (r *delayRepository) Unblock() {
 	r.Unblocker.Do(func() {
 		close(r.UnblockChannel)
+		r.Triggered = true
 	})
 }
 
@@ -600,6 +606,7 @@ func TestCheckerBlobTypeConfusion(t *testing.T) {
 	if !errFound {
 		t.Fatal("no error found, checker is broken")
 	}
+	test.Assert(t, delayRepo.Triggered, "delay repository did not trigger")
 }
 
 func loadBenchRepository(t *testing.B) (*checker.Checker, restic.Repository, func()) {
@@ -613,7 +620,7 @@ func loadBenchRepository(t *testing.B) (*checker.Checker, restic.Repository, fun
 	}
 
 	for _, err := range hints {
-		if _, ok := err.(*checker.ErrMixedPack); !ok {
+		if _, ok := err.(*repository.ErrMixedPack); !ok {
 			t.Fatalf("expected mixed pack hint, got %v", err)
 		}
 	}

internal/checker/testing.go

@@ -3,12 +3,10 @@ package checker
 import (
 	"context"
 	"testing"
-
-	"github.com/restic/restic/internal/restic"
 )
 
 // TestCheckRepo runs the checker on repo.
-func TestCheckRepo(t testing.TB, repo restic.Repository, skipStructure bool) {
+func TestCheckRepo(t testing.TB, repo checkerRepository) {
 	chkr := New(repo, true)
 
 	hints, errs := chkr.LoadIndex(context.TODO(), nil)
@@ -33,23 +31,21 @@ func TestCheckRepo(t testing.TB, repo restic.Repository, skipStructure bool) {
 		t.Error(err)
 	}
 
-	if !skipStructure {
-		// structure
-		errChan = make(chan error)
-		go chkr.Structure(context.TODO(), nil, errChan)
+	// structure
+	errChan = make(chan error)
+	go chkr.Structure(context.TODO(), nil, errChan)
 
-		for err := range errChan {
-			t.Error(err)
-		}
+	for err := range errChan {
+		t.Error(err)
+	}
 
-		// unused blobs
-		blobs, err := chkr.UnusedBlobs(context.TODO())
-		if err != nil {
-			t.Error(err)
-		}
-		if len(blobs) > 0 {
-			t.Errorf("unused blobs found: %v", blobs)
-		}
+	// unused blobs
+	blobs, err := chkr.UnusedBlobs(context.TODO())
+	if err != nil {
+		t.Error(err)
+	}
+	if len(blobs) > 0 {
+		t.Errorf("unused blobs found: %v", blobs)
 	}
 
 	// read data

internal/data/testing_test.go

@@ -46,7 +46,7 @@ func TestCreateSnapshot(t *testing.T) {
 		t.Fatalf("snapshot has zero tree ID")
 	}
 
-	checker.TestCheckRepo(t, repo, false)
+	checker.TestCheckRepo(t, repo)
 }
 
 func BenchmarkTestCreateSnapshot(t *testing.B) {

internal/repository/checker.go

@@ -0,0 +1,287 @@
+package repository
+
+import (
+	"bufio"
+	"context"
+	"fmt"
+
+	"github.com/klauspost/compress/zstd"
+	"github.com/restic/restic/internal/debug"
+	"github.com/restic/restic/internal/errors"
+	"github.com/restic/restic/internal/repository/index"
+	"github.com/restic/restic/internal/repository/pack"
+	"github.com/restic/restic/internal/restic"
+	"github.com/restic/restic/internal/ui/progress"
+	"golang.org/x/sync/errgroup"
+)
+
+const maxStreamBufferSize = 4 * 1024 * 1024
+
+// ErrDuplicatePacks is returned when a pack is found in more than one index.
+type ErrDuplicatePacks struct {
+	PackID  restic.ID
+	Indexes restic.IDSet
+}
+
+func (e *ErrDuplicatePacks) Error() string {
+	return fmt.Sprintf("pack %v contained in several indexes: %v", e.PackID, e.Indexes)
+}
+
+// ErrMixedPack is returned when a pack is found that contains both tree and data blobs.
+type ErrMixedPack struct {
+	PackID restic.ID
+}
+
+func (e *ErrMixedPack) Error() string {
+	return fmt.Sprintf("pack %v contains a mix of tree and data blobs", e.PackID.Str())
+}
+
+// PackError describes an error with a specific pack.
+type PackError struct {
+	ID        restic.ID
+	Orphaned  bool
+	Truncated bool
+	Err       error
+}
+
+func (e *PackError) Error() string {
+	return "pack " + e.ID.String() + ": " + e.Err.Error()
+}
+
+// Checker handles index-related operations for repository checking.
+type Checker struct {
+	packs map[restic.ID]int64
+	repo  *Repository
+}
+
+// NewChecker creates a new Checker.
+func NewChecker(repo *Repository) *Checker {
+	return &Checker{
+		packs: make(map[restic.ID]int64),
+		repo:  repo,
+	}
+}
+func computePackTypes(ctx context.Context, idx restic.ListBlobser) (map[restic.ID]restic.BlobType, error) {
+	packs := make(map[restic.ID]restic.BlobType)
+	err := idx.ListBlobs(ctx, func(pb restic.PackedBlob) {
+		tpe, exists := packs[pb.PackID]
+		if exists {
+			if pb.Type != tpe {
+				tpe = restic.InvalidBlob
+			}
+		} else {
+			tpe = pb.Type
+		}
+		packs[pb.PackID] = tpe
+	})
+	return packs, err
+}
+
+// LoadIndex loads all index files.
+func (c *Checker) LoadIndex(ctx context.Context, p restic.TerminalCounterFactory) (hints []error, errs []error) {
+	debug.Log("Start")
+	packToIndex := make(map[restic.ID]restic.IDSet)
+
+	// Use the repository's internal loadIndexWithCallback to handle per-index errors
+	err := c.repo.loadIndexWithCallback(ctx, p, func(id restic.ID, idx *index.Index, err error) error {
+		debug.Log("process index %v, err %v", id, err)
+		err = errors.Wrapf(err, "error loading index %v", id)
+
+		if err != nil {
+			errs = append(errs, err)
+			return nil
+		}
+
+		debug.Log("process blobs")
+		cnt := 0
+		err = idx.Each(ctx, func(blob restic.PackedBlob) {
+			cnt++
+
+			if _, ok := packToIndex[blob.PackID]; !ok {
+				packToIndex[blob.PackID] = restic.NewIDSet()
+			}
+			packToIndex[blob.PackID].Insert(id)
+		})
+
+		debug.Log("%d blobs processed", cnt)
+		return err
+	})
+	if err != nil {
+		// failed to load the index
+		return hints, append(errs, err)
+	}
+
+	// compute pack size using index entries
+	c.packs, err = pack.Size(ctx, c.repo, false)
+	if err != nil {
+		return hints, append(errs, err)
+	}
+	packTypes, err := computePackTypes(ctx, c.repo)
+	if err != nil {
+		return hints, append(errs, err)
+	}
+
+	debug.Log("checking for duplicate packs")
+	for packID := range c.packs {
+		debug.Log("  check pack %v: contained in %d indexes", packID, len(packToIndex[packID]))
+		if len(packToIndex[packID]) > 1 {
+			hints = append(hints, &ErrDuplicatePacks{
+				PackID:  packID,
+				Indexes: packToIndex[packID],
+			})
+		}
+		if packTypes[packID] == restic.InvalidBlob {
+			hints = append(hints, &ErrMixedPack{
+				PackID: packID,
+			})
+		}
+	}
+
+	return hints, errs
+}
+
+// Packs checks that all packs referenced in the index are still available and
+// there are no packs that aren't in an index. errChan is closed after all
+// packs have been checked.
+func (c *Checker) Packs(ctx context.Context, errChan chan<- error) {
+	defer close(errChan)
+	debug.Log("checking for %d packs", len(c.packs))
+
+	debug.Log("listing repository packs")
+	repoPacks := make(map[restic.ID]int64)
+
+	err := c.repo.List(ctx, restic.PackFile, func(id restic.ID, size int64) error {
+		repoPacks[id] = size
+		return nil
+	})
+
+	if err != nil {
+		errChan <- err
+	}
+
+	for id, size := range c.packs {
+		reposize, ok := repoPacks[id]
+		// remove from repoPacks so we can find orphaned packs
+		delete(repoPacks, id)
+
+		// missing: present in c.packs but not in the repo
+		if !ok {
+			select {
+			case <-ctx.Done():
+				return
+			case errChan <- &PackError{ID: id, Err: errors.New("does not exist")}:
+			}
+			continue
+		}
+
+		// size not matching: present in c.packs and in the repo, but sizes do not match
+		if size != reposize {
+			select {
+			case <-ctx.Done():
+				return
+			case errChan <- &PackError{ID: id, Truncated: true, Err: errors.Errorf("unexpected file size: got %d, expected %d", reposize, size)}:
+			}
+		}
+	}
+
+	// orphaned: present in the repo but not in c.packs
+	for orphanID := range repoPacks {
+		select {
+		case <-ctx.Done():
+			return
+		case errChan <- &PackError{ID: orphanID, Orphaned: true, Err: errors.New("not referenced in any index")}:
+		}
+	}
+}
+
+// CountPacks returns the number of packs in the repository.
+func (c *Checker) CountPacks() uint64 {
+	return uint64(len(c.packs))
+}
+
+// GetPacks returns IDSet of packs in the repository
+func (c *Checker) GetPacks() map[restic.ID]int64 {
+	return c.packs
+}
+
+// ReadData loads all data from the repository and checks the integrity.
+func (c *Checker) ReadData(ctx context.Context, errChan chan<- error) {
+	c.ReadPacks(ctx, c.packs, nil, errChan)
+}
+
+// ReadPacks loads data from specified packs and checks the integrity.
+func (c *Checker) ReadPacks(ctx context.Context, packs map[restic.ID]int64, p *progress.Counter, errChan chan<- error) {
+	defer close(errChan)
+
+	g, ctx := errgroup.WithContext(ctx)
+	type checkTask struct {
+		id    restic.ID
+		size  int64
+		blobs []restic.Blob
+	}
+	ch := make(chan checkTask)
+
+	// as packs are streamed the concurrency is limited by IO
+	workerCount := int(c.repo.Connections())
+	// run workers
+	for i := 0; i < workerCount; i++ {
+		g.Go(func() error {
+			bufRd := bufio.NewReaderSize(nil, maxStreamBufferSize)
+			dec, err := zstd.NewReader(nil)
+			if err != nil {
+				panic(dec)
+			}
+			defer dec.Close()
+			for {
+				var ps checkTask
+				var ok bool
+
+				select {
+				case <-ctx.Done():
+					return nil
+				case ps, ok = <-ch:
+					if !ok {
+						return nil
+					}
+				}
+
+				err := CheckPack(ctx, c.repo, ps.id, ps.blobs, ps.size, bufRd, dec)
+				p.Add(1)
+				if err == nil {
+					continue
+				}
+
+				select {
+				case <-ctx.Done():
+					return nil
+				case errChan <- err:
+				}
+			}
+		})
+	}
+
+	packSet := restic.NewIDSet()
+	for pack := range packs {
+		packSet.Insert(pack)
+	}
+
+	// push packs to ch
+	for pbs := range c.repo.ListPacksFromIndex(ctx, packSet) {
+		size := packs[pbs.PackID]
+		debug.Log("listed %v", pbs.PackID)
+		select {
+		case ch <- checkTask{id: pbs.PackID, size: size, blobs: pbs.Blobs}:
+		case <-ctx.Done():
+		}
+	}
+	close(ch)
+
+	err := g.Wait()
+	if err != nil {
+		select {
+		case <-ctx.Done():
+			return
+		case errChan <- err:
+		}
+	}
+}

internal/repository/index/master_index_test.go

@@ -347,7 +347,7 @@ var (
 	depth        = 3
 )
 
-func createFilledRepo(t testing.TB, snapshots int, version uint) (restic.Repository, restic.Unpacked[restic.FileType]) {
+func createFilledRepo(t testing.TB, snapshots int, version uint) (*repository.Repository, restic.Unpacked[restic.FileType]) {
 	repo, unpacked, _ := repository.TestRepositoryWithVersion(t, version)
 
 	for i := 0; i < snapshots; i++ {
@@ -402,7 +402,7 @@ func testIndexSave(t *testing.T, version uint) {
 			}))
 			rtest.Equals(t, 0, len(blobs), "saved index is missing blobs")
 
-			checker.TestCheckRepo(t, repo, false)
+			checker.TestCheckRepo(t, repo)
 		})
 	}
 }
@@ -449,7 +449,7 @@ func testIndexSavePartial(t *testing.T, version uint) {
 	// remove pack files to make check happy
 	rtest.OK(t, restic.ParallelRemove(context.TODO(), unpacked, newPacks, restic.PackFile, nil, nil))
 
-	checker.TestCheckRepo(t, repo, false)
+	checker.TestCheckRepo(t, repo)
 }
 
 func listPacks(t testing.TB, repo restic.Lister) restic.IDSet {

internal/repository/prune_test.go

@@ -8,7 +8,6 @@ import (
 	"testing"
 	"time"
 
-	"github.com/restic/restic/internal/checker"
 	"github.com/restic/restic/internal/repository"
 	"github.com/restic/restic/internal/repository/pack"
 	"github.com/restic/restic/internal/restic"
@@ -49,7 +48,7 @@ func testPrune(t *testing.T, opts repository.PruneOptions, errOnUnused bool) {
 	rtest.OK(t, plan.Execute(context.TODO(), &progress.NoopPrinter{}))
 
 	repo = repository.TestOpenBackend(t, be)
-	checker.TestCheckRepo(t, repo, true)
+	repository.TestCheckRepo(t, repo)
 
 	if errOnUnused {
 		existing := listBlobs(repo)
@@ -181,7 +180,7 @@ func TestPruneSmall(t *testing.T) {
 
 	// repopen repository
 	repo = repository.TestOpenBackend(t, be)
-	checker.TestCheckRepo(t, repo, true)
+	repository.TestCheckRepo(t, repo)
 
 	// load all blobs
 	for blob := range keep {

internal/repository/repair_index.go

@@ -32,30 +32,18 @@ func RepairIndex(ctx context.Context, repo *Repository, opts RepairIndexOptions,
 
 	} else {
 		printer.P("loading indexes...\n")
-		mi := index.NewMasterIndex()
-		err := index.ForAllIndexes(ctx, repo, repo, func(id restic.ID, idx *index.Index, err error) error {
+		err := repo.loadIndexWithCallback(ctx, nil, func(id restic.ID, _ *index.Index, err error) error {
 			if err != nil {
 				printer.E("removing invalid index %v: %v\n", id, err)
 				obsoleteIndexes = append(obsoleteIndexes, id)
 				return nil
 			}
-
-			mi.Insert(idx)
 			return nil
 		})
 		if err != nil {
 			return err
 		}
 
-		err = mi.MergeFinalIndexes()
-		if err != nil {
-			return err
-		}
-
-		err = repo.SetIndex(mi)
-		if err != nil {
-			return err
-		}
 		packSizeFromIndex, err = pack.Size(ctx, repo, false)
 		if err != nil {
 			return err

internal/repository/repair_index_test.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"github.com/restic/restic/internal/backend"
-	"github.com/restic/restic/internal/checker"
 	"github.com/restic/restic/internal/repository"
 	"github.com/restic/restic/internal/restic"
 	rtest "github.com/restic/restic/internal/test"
@@ -36,7 +35,7 @@ func testRebuildIndex(t *testing.T, readAllPacks bool, damage func(t *testing.T,
 		ReadAllPacks: readAllPacks,
 	}, &progress.NoopPrinter{}))
 
-	checker.TestCheckRepo(t, repo, true)
+	repository.TestCheckRepo(t, repo)
 }
 
 func TestRebuildIndex(t *testing.T) {

internal/repository/repository.go

@@ -178,6 +178,10 @@ func (r *Repository) SetDryRun() {
 	r.be = dryrun.New(r.be)
 }
 
+func (r *Repository) Checker() *Checker {
+	return NewChecker(r)
+}
+
 // LoadUnpacked loads and decrypts the file with the given type and ID.
 func (r *Repository) LoadUnpacked(ctx context.Context, t restic.FileType, id restic.ID) ([]byte, error) {
 	debug.Log("load %v with id %v", t, id)
@@ -628,18 +632,17 @@ func (r *Repository) ListPacksFromIndex(ctx context.Context, packs restic.IDSet)
 	return r.idx.ListPacks(ctx, packs)
 }
 
-// SetIndex instructs the repository to use the given index.
-func (r *Repository) SetIndex(i restic.MasterIndex) error {
-	r.idx = i.(*index.MasterIndex)
-	return r.prepareCache()
-}
-
 func (r *Repository) clearIndex() {
 	r.idx = index.NewMasterIndex()
 }
 
 // LoadIndex loads all index files from the backend in parallel and stores them
 func (r *Repository) LoadIndex(ctx context.Context, p restic.TerminalCounterFactory) error {
+	return r.loadIndexWithCallback(ctx, p, nil)
+}
+
+// loadIndexWithCallback loads all index files from the backend in parallel and stores them
+func (r *Repository) loadIndexWithCallback(ctx context.Context, p restic.TerminalCounterFactory, cb func(id restic.ID, idx *index.Index, err error) error) error {
 	debug.Log("Loading index")
 
 	// reset in-memory index before loading it from the repository
@@ -650,7 +653,7 @@ func (r *Repository) LoadIndex(ctx context.Context, p restic.TerminalCounterFact
 		bar = p.NewCounterTerminalOnly("index files loaded")
 	}
 
-	err := r.idx.Load(ctx, r, bar, nil)
+	err := r.idx.Load(ctx, r, bar, cb)
 	if err != nil {
 		return err
 	}

internal/repository/repository_test.go

@@ -16,7 +16,6 @@ import (
 	"github.com/restic/restic/internal/backend/cache"
 	"github.com/restic/restic/internal/backend/local"
 	"github.com/restic/restic/internal/backend/mem"
-	"github.com/restic/restic/internal/checker"
 	"github.com/restic/restic/internal/crypto"
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/repository"
@@ -131,7 +130,7 @@ func testSavePackMerging(t *testing.T, targetPercentage int, expectedPacks int)
 	}))
 	rtest.Equals(t, expectedPacks, packs, "unexpected number of pack files")
 
-	checker.TestCheckRepo(t, repo, true)
+	repository.TestCheckRepo(t, repo)
 }
 
 func BenchmarkSaveAndEncrypt(t *testing.B) {

internal/repository/testing.go

@@ -162,3 +162,33 @@ func TestNewLock(_ *testing.T, repo *Repository, exclusive bool) (*restic.Lock,
 	// TODO get rid of this test helper
 	return restic.NewLock(context.TODO(), &internalRepository{repo}, exclusive)
 }
+
+// TestCheckRepo runs the checker on repo.
+func TestCheckRepo(t testing.TB, repo *Repository) {
+	chkr := NewChecker(repo)
+
+	hints, errs := chkr.LoadIndex(context.TODO(), nil)
+	if len(errs) != 0 {
+		t.Fatalf("errors loading index: %v", errs)
+	}
+
+	if len(hints) != 0 {
+		t.Fatalf("errors loading index: %v", hints)
+	}
+
+	// packs
+	errChan := make(chan error)
+	go chkr.Packs(context.TODO(), errChan)
+
+	for err := range errChan {
+		t.Error(err)
+	}
+
+	// read data
+	errChan = make(chan error)
+	go chkr.ReadData(context.TODO(), errChan)
+
+	for err := range errChan {
+		t.Error(err)
+	}
+}

internal/restic/repository.go

@@ -22,7 +22,6 @@ type Repository interface {
 	Key() *crypto.Key
 
 	LoadIndex(ctx context.Context, p TerminalCounterFactory) error
-	SetIndex(mi MasterIndex) error
 
 	LookupBlob(t BlobType, id ID) []PackedBlob
 	LookupBlobSize(t BlobType, id ID) (size uint, exists bool)
@@ -137,17 +136,6 @@ type TerminalCounterFactory interface {
 	NewCounterTerminalOnly(description string) *progress.Counter
 }
 
-// MasterIndex keeps track of the blobs are stored within files.
-type MasterIndex interface {
-	Has(bh BlobHandle) bool
-	Lookup(bh BlobHandle) []PackedBlob
-
-	// Each runs fn on all blobs known to the index. When the context is cancelled,
-	// the index iteration returns immediately with ctx.Err(). This blocks any modification of the index.
-	Each(ctx context.Context, fn func(PackedBlob)) error
-	ListPacks(ctx context.Context, packs IDSet) <-chan PackBlobs
-}
-
 // Lister allows listing files in a backend.
 type Lister interface {
 	List(ctx context.Context, t FileType, fn func(ID, int64) error) error