backend: Split RetryBackend into own package

The RetryBackend tests depend on the mock backend. When the Backend
interface is eventually split from the restic package, this will lead to
a dependency cycle between backend and backend/mock. Thus split the
RetryBackend into a separate package to avoid this problem.

cmd/restic/global.go

@@ -22,6 +22,7 @@ import (
 	"github.com/restic/restic/internal/backend/location"
 	"github.com/restic/restic/internal/backend/rclone"
 	"github.com/restic/restic/internal/backend/rest"
+	"github.com/restic/restic/internal/backend/retry"
 	"github.com/restic/restic/internal/backend/s3"
 	"github.com/restic/restic/internal/backend/sftp"
 	"github.com/restic/restic/internal/backend/swift"
@@ -445,7 +446,7 @@ func OpenRepository(ctx context.Context, opts GlobalOptions) (*repository.Reposi
 	success := func(msg string, retries int) {
 		Warnf("%v operation successful after %d retries\n", msg, retries)
 	}
-	be = backend.NewRetryBackend(be, 10, report, success)
+	be = retry.New(be, 10, report, success)
 
 	// wrap backend if a test specified a hook
 	if opts.backendTestHook != nil {

cmd/restic/integration_helpers_test.go

@@ -9,7 +9,7 @@ import (
 	"runtime"
 	"testing"
 
-	"github.com/restic/restic/internal/backend"
+	"github.com/restic/restic/internal/backend/retry"
 	"github.com/restic/restic/internal/options"
 	"github.com/restic/restic/internal/repository"
 	"github.com/restic/restic/internal/restic"
@@ -172,7 +172,7 @@ func withTestEnvironment(t testing.TB) (env *testEnvironment, cleanup func()) {
 
 	repository.TestUseLowSecurityKDFParameters(t)
 	restic.TestDisableCheckPolynomial(t)
-	backend.TestFastRetries(t)
+	retry.TestFastRetries(t)
 
 	tempdir, err := ioutil.TempDir(rtest.TestTempDir, "restic-test-")
 	rtest.OK(t, err)

internal/backend/retry/backend_retry.go

@@ -1,4 +1,4 @@
-package backend
+package retry
 
 import (
 	"context"
@@ -11,9 +11,9 @@ import (
 	"github.com/restic/restic/internal/restic"
 )
 
-// RetryBackend retries operations on the backend in case of an error with a
+// Backend retries operations on the backend in case of an error with a
 // backoff.
-type RetryBackend struct {
+type Backend struct {
 	restic.Backend
 	MaxTries int
 	Report   func(string, error, time.Duration)
@@ -21,14 +21,14 @@ type RetryBackend struct {
 }
 
 // statically ensure that RetryBackend implements restic.Backend.
-var _ restic.Backend = &RetryBackend{}
+var _ restic.Backend = &Backend{}
 
-// NewRetryBackend wraps be with a backend that retries operations after a
+// New wraps be with a backend that retries operations after a
 // backoff. report is called with a description and the error, if one occurred.
 // success is called with the number of retries before a successful operation
 // (it is not called if it succeeded on the first try)
-func NewRetryBackend(be restic.Backend, maxTries int, report func(string, error, time.Duration), success func(string, int)) *RetryBackend {
-	return &RetryBackend{
+func New(be restic.Backend, maxTries int, report func(string, error, time.Duration), success func(string, int)) *Backend {
+	return &Backend{
 		Backend:  be,
 		MaxTries: maxTries,
 		Report:   report,
@@ -57,7 +57,7 @@ func retryNotifyErrorWithSuccess(operation backoff.Operation, b backoff.BackOff,
 
 var fastRetries = false
 
-func (be *RetryBackend) retry(ctx context.Context, msg string, f func() error) error {
+func (be *Backend) retry(ctx context.Context, msg string, f func() error) error {
 	// Don't do anything when called with an already cancelled context. There would be
 	// no retries in that case either, so be consistent and abort always.
 	// This enforces a strict contract for backend methods: Using a cancelled context
@@ -92,7 +92,7 @@ func (be *RetryBackend) retry(ctx context.Context, msg string, f func() error) e
 }
 
 // Save stores the data in the backend under the given handle.
-func (be *RetryBackend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
+func (be *Backend) Save(ctx context.Context, h restic.Handle, rd restic.RewindReader) error {
 	return be.retry(ctx, fmt.Sprintf("Save(%v)", h), func() error {
 		err := rd.Rewind()
 		if err != nil {
@@ -125,7 +125,7 @@ func (be *RetryBackend) Save(ctx context.Context, h restic.Handle, rd restic.Rew
 // given offset. If length is larger than zero, only a portion of the file
 // is returned. rd must be closed after use. If an error is returned, the
 // ReadCloser must be nil.
-func (be *RetryBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64, consumer func(rd io.Reader) error) (err error) {
+func (be *Backend) Load(ctx context.Context, h restic.Handle, length int, offset int64, consumer func(rd io.Reader) error) (err error) {
 	return be.retry(ctx, fmt.Sprintf("Load(%v, %v, %v)", h, length, offset),
 		func() error {
 			return be.Backend.Load(ctx, h, length, offset, consumer)
@@ -133,7 +133,7 @@ func (be *RetryBackend) Load(ctx context.Context, h restic.Handle, length int, o
 }
 
 // Stat returns information about the File identified by h.
-func (be *RetryBackend) Stat(ctx context.Context, h restic.Handle) (fi restic.FileInfo, err error) {
+func (be *Backend) Stat(ctx context.Context, h restic.Handle) (fi restic.FileInfo, err error) {
 	err = be.retry(ctx, fmt.Sprintf("Stat(%v)", h),
 		func() error {
 			var innerError error
@@ -145,14 +145,14 @@ func (be *RetryBackend) Stat(ctx context.Context, h restic.Handle) (fi restic.Fi
 }
 
 // Remove removes a File with type t and name.
-func (be *RetryBackend) Remove(ctx context.Context, h restic.Handle) (err error) {
+func (be *Backend) Remove(ctx context.Context, h restic.Handle) (err error) {
 	return be.retry(ctx, fmt.Sprintf("Remove(%v)", h), func() error {
 		return be.Backend.Remove(ctx, h)
 	})
 }
 
 // Test a boolean value whether a File with the name and type exists.
-func (be *RetryBackend) Test(ctx context.Context, h restic.Handle) (exists bool, err error) {
+func (be *Backend) Test(ctx context.Context, h restic.Handle) (exists bool, err error) {
 	err = be.retry(ctx, fmt.Sprintf("Test(%v)", h), func() error {
 		var innerError error
 		exists, innerError = be.Backend.Test(ctx, h)
@@ -166,7 +166,7 @@ func (be *RetryBackend) Test(ctx context.Context, h restic.Handle) (exists bool,
 // error is returned by the underlying backend, the request is retried. When fn
 // returns an error, the operation is aborted and the error is returned to the
 // caller.
-func (be *RetryBackend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
+func (be *Backend) List(ctx context.Context, t restic.FileType, fn func(restic.FileInfo) error) error {
 	// create a new context that we can cancel when fn returns an error, so
 	// that listing is aborted
 	listCtx, cancel := context.WithCancel(ctx)

internal/backend/retry/backend_retry_test.go

@@ -1,4 +1,4 @@
-package backend
+package retry
 
 import (
 	"bytes"
@@ -36,7 +36,7 @@ func TestBackendSaveRetry(t *testing.T) {
 	}
 
 	TestFastRetries(t)
-	retryBackend := NewRetryBackend(be, 10, nil, nil)
+	retryBackend := New(be, 10, nil, nil)
 
 	data := test.Random(23, 5*1024*1024+11241)
 	err := retryBackend.Save(context.TODO(), restic.Handle{}, restic.NewByteReader(data, be.Hasher()))
@@ -72,7 +72,7 @@ func TestBackendSaveRetryAtomic(t *testing.T) {
 	}
 
 	TestFastRetries(t)
-	retryBackend := NewRetryBackend(be, 10, nil, nil)
+	retryBackend := New(be, 10, nil, nil)
 
 	data := test.Random(23, 5*1024*1024+11241)
 	err := retryBackend.Save(context.TODO(), restic.Handle{}, restic.NewByteReader(data, be.Hasher()))
@@ -106,7 +106,7 @@ func TestBackendListRetry(t *testing.T) {
 	}
 
 	TestFastRetries(t)
-	retryBackend := NewRetryBackend(be, 10, nil, nil)
+	retryBackend := New(be, 10, nil, nil)
 
 	var listed []string
 	err := retryBackend.List(context.TODO(), restic.PackFile, func(fi restic.FileInfo) error {
@@ -136,7 +136,7 @@ func TestBackendListRetryErrorFn(t *testing.T) {
 	}
 
 	TestFastRetries(t)
-	retryBackend := NewRetryBackend(be, 10, nil, nil)
+	retryBackend := New(be, 10, nil, nil)
 
 	var ErrTest = errors.New("test error")
 
@@ -193,7 +193,7 @@ func TestBackendListRetryErrorBackend(t *testing.T) {
 
 	TestFastRetries(t)
 	const maxRetries = 2
-	retryBackend := NewRetryBackend(be, maxRetries, nil, nil)
+	retryBackend := New(be, maxRetries, nil, nil)
 
 	var listed []string
 	err := retryBackend.List(context.TODO(), restic.PackFile, func(fi restic.FileInfo) error {
@@ -263,7 +263,7 @@ func TestBackendLoadRetry(t *testing.T) {
 	}
 
 	TestFastRetries(t)
-	retryBackend := NewRetryBackend(be, 10, nil, nil)
+	retryBackend := New(be, 10, nil, nil)
 
 	var buf []byte
 	err := retryBackend.Load(context.TODO(), restic.Handle{}, 0, 0, func(rd io.Reader) (err error) {
@@ -283,7 +283,7 @@ func TestBackendCanceledContext(t *testing.T) {
 	// unimplemented mock backend functions return an error by default
 	// check that we received the expected context canceled error instead
 	TestFastRetries(t)
-	retryBackend := NewRetryBackend(mock.NewBackend(), 2, nil, nil)
+	retryBackend := New(mock.NewBackend(), 2, nil, nil)
 	h := restic.Handle{Type: restic.PackFile, Name: restic.NewRandomID().String()}
 
 	// create an already canceled context

internal/backend/retry/testing.go

@@ -1,4 +1,4 @@
-package backend
+package retry
 
 import "testing"