swift: obey Retry-After to fix OVH restore from cold storage

In as many methods as possible we attempt to obey the Retry-After
header where it is provided.

This means that when objects are being requested from OVH cold storage
rclone will sleep the correct amount of time before retrying.

If the sleeps are short it does them immediately, if long then it
returns an ErrorRetryAfter which will cause the outer retry to sleep
before retrying.

Fixes #3041

backend/swift/swift.go

@@ -286,6 +286,31 @@ func shouldRetry(err error) (bool, error) {
 	return fserrors.ShouldRetry(err), err
 }
 
+// shouldRetryHeaders returns a boolean as to whether this err
+// deserves to be retried.  It reads the headers passed in looking for
+// `Retry-After`. It returns the err as a convenience
+func shouldRetryHeaders(headers swift.Headers, err error) (bool, error) {
+	if swiftError, ok := err.(*swift.Error); ok && swiftError.StatusCode == 429 {
+		if value := headers["Retry-After"]; value != "" {
+			retryAfter, parseErr := strconv.Atoi(value)
+			if parseErr != nil {
+				fs.Errorf(nil, "Failed to parse Retry-After: %q: %v", value, parseErr)
+			} else {
+				duration := time.Second * time.Duration(retryAfter)
+				if duration <= 60*time.Second {
+					// Do a short sleep immediately
+					fs.Debugf(nil, "Sleeping for %v to obey Retry-After", duration)
+					time.Sleep(duration)
+					return true, err
+				}
+				// Delay a long sleep for a retry
+				return false, fserrors.NewErrorRetryAfter(duration)
+			}
+		}
+	}
+	return shouldRetry(err)
+}
+
 // Pattern to match a swift path
 var matcher = regexp.MustCompile(`^/*([^/]*)(.*)$`)
 
@@ -413,8 +438,9 @@ func NewFsWithConnection(opt *Options, name, root string, c *swift.Connection, n
 		// Check to see if the object exists - ignoring directory markers
 		var info swift.Object
 		err = f.pacer.Call(func() (bool, error) {
-			info, _, err = f.c.Object(container, directory)
+			var rxHeaders swift.Headers
-			return shouldRetry(err)
+			info, rxHeaders, err = f.c.Object(container, directory)
+			return shouldRetryHeaders(rxHeaders, err)
 		})
 		if err == nil && info.ContentType != directoryMarkerContentType {
 			f.root = path.Dir(directory)
@@ -723,8 +749,9 @@ func (f *Fs) Mkdir(dir string) error {
 	var err error = swift.ContainerNotFound
 	if !f.noCheckContainer {
 		err = f.pacer.Call(func() (bool, error) {
-			_, _, err = f.c.Container(f.container)
+			var rxHeaders swift.Headers
-			return shouldRetry(err)
+			_, rxHeaders, err = f.c.Container(f.container)
+			return shouldRetryHeaders(rxHeaders, err)
 		})
 	}
 	if err == swift.ContainerNotFound {
@@ -816,8 +843,9 @@ func (f *Fs) Copy(src fs.Object, remote string) (fs.Object, error) {
 	}
 	srcFs := srcObj.fs
 	err = f.pacer.Call(func() (bool, error) {
-		_, err = f.c.ObjectCopy(srcFs.container, srcFs.root+srcObj.remote, f.container, f.root+remote, nil)
+		var rxHeaders swift.Headers
-		return shouldRetry(err)
+		rxHeaders, err = f.c.ObjectCopy(srcFs.container, srcFs.root+srcObj.remote, f.container, f.root+remote, nil)
+		return shouldRetryHeaders(rxHeaders, err)
 	})
 	if err != nil {
 		return nil, err
@@ -927,7 +955,7 @@ func (o *Object) readMetaData() (err error) {
 	var h swift.Headers
 	err = o.fs.pacer.Call(func() (bool, error) {
 		info, h, err = o.fs.c.Object(o.fs.container, o.fs.root+o.remote)
-		return shouldRetry(err)
+		return shouldRetryHeaders(h, err)
 	})
 	if err != nil {
 		if err == swift.ObjectNotFound {
@@ -1002,8 +1030,9 @@ func (o *Object) Open(options ...fs.OpenOption) (in io.ReadCloser, err error) {
 	headers := fs.OpenOptionHeaders(options)
 	_, isRanging := headers["Range"]
 	err = o.fs.pacer.Call(func() (bool, error) {
-		in, _, err = o.fs.c.ObjectOpen(o.fs.container, o.fs.root+o.remote, !isRanging, headers)
+		var rxHeaders swift.Headers
-		return shouldRetry(err)
+		in, rxHeaders, err = o.fs.c.ObjectOpen(o.fs.container, o.fs.root+o.remote, !isRanging, headers)
+		return shouldRetryHeaders(rxHeaders, err)
 	})
 	return
 }
@@ -1074,8 +1103,9 @@ func (o *Object) updateChunks(in0 io.Reader, headers swift.Headers, size int64,
 	// Create the segmentsContainer if it doesn't exist
 	var err error
 	err = o.fs.pacer.Call(func() (bool, error) {
-		_, _, err = o.fs.c.Container(o.fs.segmentsContainer)
+		var rxHeaders swift.Headers
-		return shouldRetry(err)
+		_, rxHeaders, err = o.fs.c.Container(o.fs.segmentsContainer)
+		return shouldRetryHeaders(rxHeaders, err)
 	})
 	if err == swift.ContainerNotFound {
 		headers := swift.Headers{}
@@ -1115,8 +1145,9 @@ func (o *Object) updateChunks(in0 io.Reader, headers swift.Headers, size int64,
 		segmentPath := fmt.Sprintf("%s/%08d", segmentsPath, i)
 		fs.Debugf(o, "Uploading segment file %q into %q", segmentPath, o.fs.segmentsContainer)
 		err = o.fs.pacer.CallNoRetry(func() (bool, error) {
-			_, err = o.fs.c.ObjectPut(o.fs.segmentsContainer, segmentPath, segmentReader, true, "", "", headers)
+			var rxHeaders swift.Headers
-			return shouldRetry(err)
+			rxHeaders, err = o.fs.c.ObjectPut(o.fs.segmentsContainer, segmentPath, segmentReader, true, "", "", headers)
+			return shouldRetryHeaders(rxHeaders, err)
 		})
 		if err != nil {
 			return "", err
@@ -1129,8 +1160,9 @@ func (o *Object) updateChunks(in0 io.Reader, headers swift.Headers, size int64,
 	emptyReader := bytes.NewReader(nil)
 	manifestName := o.fs.root + o.remote
 	err = o.fs.pacer.Call(func() (bool, error) {
-		_, err = o.fs.c.ObjectPut(o.fs.container, manifestName, emptyReader, true, "", contentType, headers)
+		var rxHeaders swift.Headers
-		return shouldRetry(err)
+		rxHeaders, err = o.fs.c.ObjectPut(o.fs.container, manifestName, emptyReader, true, "", contentType, headers)
+		return shouldRetryHeaders(rxHeaders, err)
 	})
 	return uniquePrefix + "/", err
 }
@@ -1174,7 +1206,7 @@ func (o *Object) Update(in io.Reader, src fs.ObjectInfo, options ...fs.OpenOptio
 		var rxHeaders swift.Headers
 		err = o.fs.pacer.CallNoRetry(func() (bool, error) {
 			rxHeaders, err = o.fs.c.ObjectPut(o.fs.container, o.fs.root+o.remote, in, true, "", contentType, headers)
-			return shouldRetry(err)
+			return shouldRetryHeaders(rxHeaders, err)
 		})
 		if err != nil {
 			return err

backend/swift/swift_internal_test.go

@@ -1,6 +1,13 @@
 package swift
 
-import "testing"
+import (
+	"testing"
+	"time"
+
+	"github.com/ncw/rclone/fs/fserrors"
+	"github.com/ncw/swift"
+	"github.com/stretchr/testify/assert"
+)
 
 func TestInternalUrlEncode(t *testing.T) {
 	for _, test := range []struct {
@@ -23,3 +30,37 @@ func TestInternalUrlEncode(t *testing.T) {
 		}
 	}
 }
+
+func TestInternalShouldRetryHeaders(t *testing.T) {
+	headers := swift.Headers{
+		"Content-Length": "64",
+		"Content-Type":   "text/html; charset=UTF-8",
+		"Date":           "Mon: 18 Mar 2019 12:11:23 GMT",
+		"Retry-After":    "1",
+	}
+	err := &swift.Error{
+		StatusCode: 429,
+		Text:       "Too Many Requests",
+	}
+
+	// Short sleep should just do the sleep
+	start := time.Now()
+	retry, gotErr := shouldRetryHeaders(headers, err)
+	dt := time.Since(start)
+	assert.True(t, retry)
+	assert.Equal(t, err, gotErr)
+	assert.True(t, dt > time.Second/2)
+
+	// Long sleep should return RetryError
+	headers["Retry-After"] = "3600"
+	start = time.Now()
+	retry, gotErr = shouldRetryHeaders(headers, err)
+	dt = time.Since(start)
+	assert.True(t, dt < time.Second)
+	assert.False(t, retry)
+	assert.Equal(t, true, fserrors.IsRetryAfterError(gotErr))
+	after := gotErr.(fserrors.RetryAfter).RetryAfter()
+	dt = after.Sub(start)
+	assert.True(t, dt >= time.Hour-time.Second && dt <= time.Hour+time.Second)
+
+}