send/recv: job-level bandwidth limiting

Sponsored-by: Prominic.NET, Inc.

fixes #339

config/config.go

@@ -13,6 +13,7 @@ import (
 	"github.com/pkg/errors"
 	"github.com/zrepl/yaml-config"
 
+	"github.com/zrepl/zrepl/util/datasizeunit"
 	zfsprop "github.com/zrepl/zrepl/zfs/property"
 )
 
@@ -87,6 +88,8 @@ type SendOptions struct {
 	Compressed       bool `yaml:"compressed,optional,default=false"`
 	EmbeddedData     bool `yaml:"embbeded_data,optional,default=false"`
 	Saved            bool `yaml:"saved,optional,default=false"`
+
+	BandwidthLimit *BandwidthLimit `yaml:"bandwidth_limit,optional,fromdefaults"`
 }
 
 type RecvOptions struct {
@@ -96,6 +99,15 @@ type RecvOptions struct {
 	// Reencrypt bool `yaml:"reencrypt"`
 
 	Properties *PropertyRecvOptions `yaml:"properties,fromdefaults"`
+
+	BandwidthLimit *BandwidthLimit `yaml:"bandwidth_limit,optional,fromdefaults"`
+}
+
+var _ yaml.Unmarshaler = &datasizeunit.Bits{}
+
+type BandwidthLimit struct {
+	Max            datasizeunit.Bits `yaml:"max,default=-1 B"`
+	BucketCapacity datasizeunit.Bits `yaml:"bucket_capacity,default=128 KiB"`
 }
 
 type Replication struct {
@@ -113,10 +125,6 @@ type ReplicationOptionsConcurrency struct {
 	SizeEstimates int `yaml:"size_estimates,optional,default=4"`
 }
 
-func (l *RecvOptions) SetDefault() {
-	*l = RecvOptions{Properties: &PropertyRecvOptions{}}
-}
-
 type PropertyRecvOptions struct {
 	Inherit  []zfsprop.Property          `yaml:"inherit,optional"`
 	Override map[zfsprop.Property]string `yaml:"override,optional"`

config/samples/bandwidth_limit.yml

@@ -0,0 +1,41 @@
+
+jobs:
+  - type: sink
+    name: "limited_sink"
+    root_fs: "fs0"
+    recv:
+      bandwidth_limit:
+        max: 12345 B
+    serve:
+      type: local
+      listener_name: localsink
+
+  - type: push
+    name: "limited_push"
+    connect:
+      type: local
+      listener_name: localsink
+      client_identity: local_backup
+    filesystems: {
+      "root<": true,
+    }
+    send:
+      bandwidth_limit:
+        max: 54321 B
+        bucket_capacity: 1024 B
+    snapshotting:
+      type: manual
+    pruning:
+      keep_sender:
+        - type: last_n
+          count: 1
+      keep_receiver:
+        - type: last_n
+          count: 1
+
+  - type: sink
+    name: "nolimit_sink"
+    root_fs: "fs1"
+    serve:
+      type: local
+      listener_name: localsink

daemon/job/build_jobs.go

@@ -8,6 +8,7 @@ import (
 	"github.com/pkg/errors"
 
 	"github.com/zrepl/zrepl/config"
+	"github.com/zrepl/zrepl/util/bandwidthlimit"
 )
 
 func JobsFromConfig(c *config.Config) ([]Job, error) {
@@ -107,3 +108,13 @@ func validateReceivingSidesDoNotOverlap(receivingRootFSs []string) error {
 	}
 	return nil
 }
+
+func buildBandwidthLimitConfig(in *config.BandwidthLimit) (c bandwidthlimit.Config, _ error) {
+	if in.Max.ToBytes() > 0 && int64(in.Max.ToBytes()) == 0 {
+		return c, fmt.Errorf("bandwidth limit `max` is too small, must at least specify one byte")
+	}
+	return bandwidthlimit.Config{
+		Max:            int64(in.Max.ToBytes()),
+		BucketCapacity: int64(in.BucketCapacity.ToBytes()),
+	}, nil
+}

daemon/job/build_jobs_sendrecvoptions.go

@@ -22,7 +22,12 @@ func buildSenderConfig(in SendingJobConfig, jobID endpoint.JobID) (*endpoint.Sen
 		return nil, errors.Wrap(err, "cannot build filesystem filter")
 	}
 	sendOpts := in.GetSendOptions()
-	return &endpoint.SenderConfig{
+	bwlim, err := buildBandwidthLimitConfig(sendOpts.BandwidthLimit)
+	if err != nil {
+		return nil, errors.Wrap(err, "cannot build bandwith limit config")
+	}
+
+	sc := &endpoint.SenderConfig{
 		FSF:   fsf,
 		JobID: jobID,
 
@@ -34,7 +39,15 @@ func buildSenderConfig(in SendingJobConfig, jobID endpoint.JobID) (*endpoint.Sen
 		SendCompressed:       sendOpts.Compressed,
 		SendEmbeddedData:     sendOpts.EmbeddedData,
 		SendSaved:            sendOpts.Saved,
-	}, nil
+
+		BandwidthLimit: bwlim,
+	}
+
+	if err := sc.Validate(); err != nil {
+		return nil, errors.Wrap(err, "cannot build sender config")
+	}
+
+	return sc, nil
 }
 
 type ReceivingJobConfig interface {
@@ -53,6 +66,12 @@ func buildReceiverConfig(in ReceivingJobConfig, jobID endpoint.JobID) (rc endpoi
 	}
 
 	recvOpts := in.GetRecvOptions()
+
+	bwlim, err := buildBandwidthLimitConfig(recvOpts.BandwidthLimit)
+	if err != nil {
+		return rc, errors.Wrap(err, "cannot build bandwith limit config")
+	}
+
 	rc = endpoint.ReceiverConfig{
 		JobID:                      jobID,
 		RootWithoutClientComponent: rootFs,
@@ -60,6 +79,8 @@ func buildReceiverConfig(in ReceivingJobConfig, jobID endpoint.JobID) (rc endpoi
 
 		InheritProperties:  recvOpts.Properties.Inherit,
 		OverrideProperties: recvOpts.Properties.Override,
+
+		BandwidthLimit: bwlim,
 	}
 	if err := rc.Validate(); err != nil {
 		return rc, errors.Wrap(err, "cannot build receiver config")

daemon/job/build_jobs_test.go

@@ -119,6 +119,14 @@ func TestSampleConfigsAreBuiltWithoutErrors(t *testing.T) {
 		t.Errorf("glob failed: %+v", err)
 	}
 
+	type additionalCheck struct {
+		state int
+		test  func(t *testing.T, jobs []Job)
+	}
+	additionalChecks := map[string]*additionalCheck{
+		"bandwidth_limit.yml": {test: testSampleConfig_BandwidthLimit},
+	}
+
 	for _, p := range paths {
 
 		if path.Ext(p) != ".yml" {
@@ -126,10 +134,20 @@ func TestSampleConfigsAreBuiltWithoutErrors(t *testing.T) {
 			continue
 		}
 
+		filename := path.Base(p)
+		t.Logf("checking for presence additonal checks for file %q", filename)
+		additionalCheck := additionalChecks[filename]
+		if additionalCheck == nil {
+			t.Logf("no additional checks")
+		} else {
+			t.Logf("additional check present")
+			additionalCheck.state = 1
+		}
+
 		t.Run(p, func(t *testing.T) {
 			c, err := config.ParseConfig(p)
 			if err != nil {
-				t.Errorf("error parsing %s:\n%+v", p, err)
+				t.Fatalf("error parsing %s:\n%+v", p, err)
 			}
 
 			t.Logf("file: %s", p)
@@ -138,11 +156,57 @@ func TestSampleConfigsAreBuiltWithoutErrors(t *testing.T) {
 			tls.FakeCertificateLoading(t)
 			jobs, err := JobsFromConfig(c)
 			t.Logf("jobs: %#v", jobs)
-			assert.NoError(t, err)
+			require.NoError(t, err)
+
+			if additionalCheck != nil {
+				additionalCheck.test(t, jobs)
+				additionalCheck.state = 2
+			}
 		})
 
 	}
 
+	for basename, c := range additionalChecks {
+		if c.state == 0 {
+			panic("univisited additional check " + basename)
+		}
+	}
+
+}
+
+func testSampleConfig_BandwidthLimit(t *testing.T, jobs []Job) {
+	require.Len(t, jobs, 3)
+
+	{
+		limitedSink, ok := jobs[0].(*PassiveSide)
+		require.True(t, ok, "%T", jobs[0])
+		limitedSinkMode, ok := limitedSink.mode.(*modeSink)
+		require.True(t, ok, "%T", limitedSink)
+
+		assert.Equal(t, int64(12345), limitedSinkMode.receiverConfig.BandwidthLimit.Max)
+		assert.Equal(t, int64(1<<17), limitedSinkMode.receiverConfig.BandwidthLimit.BucketCapacity)
+	}
+
+	{
+		limitedPush, ok := jobs[1].(*ActiveSide)
+		require.True(t, ok, "%T", jobs[1])
+		limitedPushMode, ok := limitedPush.mode.(*modePush)
+		require.True(t, ok, "%T", limitedPush)
+
+		assert.Equal(t, int64(54321), limitedPushMode.senderConfig.BandwidthLimit.Max)
+		assert.Equal(t, int64(1024), limitedPushMode.senderConfig.BandwidthLimit.BucketCapacity)
+	}
+
+	{
+		unlimitedSink, ok := jobs[2].(*PassiveSide)
+		require.True(t, ok, "%T", jobs[2])
+		unlimitedSinkMode, ok := unlimitedSink.mode.(*modeSink)
+		require.True(t, ok, "%T", unlimitedSink)
+
+		max := unlimitedSinkMode.receiverConfig.BandwidthLimit.Max
+		assert.Less(t, max, int64(0), max, "unlimited mode <=> negative value for .Max, see bandwidthlimit.Config")
+	}
+
 }
 
 func TestReplicationOptions(t *testing.T) {

docs/configuration/sendrecvoptions.rst

@@ -36,6 +36,9 @@ See the `upstream man page <https://openzfs.github.io/openzfs-docs/man/8/zfs-sen
     * - ``encrypted``
       -
       - Specific to zrepl, :ref:`see below <job-send-options-encrypted>`.
+    * - ``bandwidth_limit``
+      -
+      - Specific to zrepl, :ref:`see below <job-send-recv-options-bandwidth-limit>`.
     * - ``raw``
       - ``-w``
       - Use ``encrypted`` to only allow encrypted sends.
@@ -138,6 +141,7 @@ Recv Options
          override: {
            "org.openzfs.systemd:ignore": "on"
          }
+       bandwidth_limit: ... # see below
      ...
 
 .. _job-recv-options--inherit-and-override:
@@ -212,3 +216,25 @@ and property replication is enabled, the receiver must :ref:`inherit the followi
 * ``keylocation``
 * ``keyformat``
 * ``encryption``
+
+Common Options
+~~~~~~~~~~~~~~
+
+.. _job-send-recv-options-bandwidth-limit:
+
+Bandwidth Limit (send & recv)
+-----------------------------
+
+::
+
+   bandwidth_limit:
+     max: 23.5 MiB # -1 is the default and disabled rate limiting
+     bucket_capacity: # token bucket capacity in bytes; defaults to 128KiB
+
+Both ``send`` and ``recv`` can be limited to a maximum bandwidth through ``bandwidth_limit``.
+For most users, it should be sufficient to just set ``bandwidth_limit.max``.
+The ``bandwidth_limit.bucket_capacity`` refers to the `token bucket size <https://github.com/juju/ratelimit>`_.
+
+The bandwidth limit only applies to the payload data, i.e., the ZFS send stream.
+It does not account for transport protocol overheads.
+The scope is the job level, i.e., all :ref:`concurrent <replication-option-concurrency>` sends or incoming receives of a job share the bandwidth limit.

docs/supporters.rst

@@ -32,6 +32,7 @@ We would like to thank the following people and organizations for supporting zre
 
    <div class="fa fa-code" style="width: 1em;"></div>
 
+* |supporter-gold| Prominic.NET, Inc.
 * |supporter-std| Torsten Blum
 * |supporter-gold| Cyberiada GmbH
 * |supporter-std| `Gordon Schulz <https://github.com/azmodude>`_

endpoint/endpoint.go

@@ -14,6 +14,7 @@ import (
 	"github.com/zrepl/zrepl/daemon/logging/trace"
 
 	"github.com/zrepl/zrepl/replication/logic/pdu"
+	"github.com/zrepl/zrepl/util/bandwidthlimit"
 	"github.com/zrepl/zrepl/util/chainedio"
 	"github.com/zrepl/zrepl/util/chainlock"
 	"github.com/zrepl/zrepl/util/envconst"
@@ -34,6 +35,8 @@ type SenderConfig struct {
 	SendCompressed       bool
 	SendEmbeddedData     bool
 	SendSaved            bool
+
+	BandwidthLimit bandwidthlimit.Config
 }
 
 func (c *SenderConfig) Validate() error {
@@ -44,6 +47,9 @@ func (c *SenderConfig) Validate() error {
 	if _, err := StepHoldTag(c.JobID); err != nil {
 		return fmt.Errorf("JobID cannot be used for hold tag: %s", err)
 	}
+	if err := bandwidthlimit.ValidateConfig(c.BandwidthLimit); err != nil {
+		return errors.Wrap(err, "`Ratelimit` field invalid")
+	}
 	return nil
 }
 
@@ -54,16 +60,21 @@ type Sender struct {
 	FSFilter zfs.DatasetFilter
 	jobId    JobID
 	config   SenderConfig
+	bwLimit  bandwidthlimit.Wrapper
 }
 
 func NewSender(conf SenderConfig) *Sender {
 	if err := conf.Validate(); err != nil {
 		panic("invalid config" + err.Error())
 	}
+
+	ratelimiter := bandwidthlimit.WrapperFromConfig(conf.BandwidthLimit)
+
 	return &Sender{
 		FSFilter: conf.FSF,
 		jobId:    conf.JobID,
 		config:   conf,
+		bwLimit:  ratelimiter,
 	}
 }
 
@@ -301,12 +312,16 @@ func (s *Sender) Send(ctx context.Context, r *pdu.SendReq) (*pdu.SendRes, io.Rea
 		abstractionsCacheSingleton.TryBatchDestroy(ctx, s.jobId, sendArgs.FS, destroyTypes, keep, check)
 	}()
 
-	sendStream, err := zfs.ZFSSend(ctx, sendArgs)
+	var sendStream io.ReadCloser
+	sendStream, err = zfs.ZFSSend(ctx, sendArgs)
 	if err != nil {
 		// it's ok to not destroy the abstractions we just created here, a new send attempt will take care of it
 		return nil, nil, errors.Wrap(err, "zfs send failed")
 	}
 
+	// apply rate limit
+	sendStream = s.bwLimit.WrapReadCloser(sendStream)
+
 	return res, sendStream, nil
 }
 
@@ -439,6 +454,8 @@ type ReceiverConfig struct {
 
 	InheritProperties  []zfsprop.Property
 	OverrideProperties map[zfsprop.Property]string
+
+	BandwidthLimit bandwidthlimit.Config
 }
 
 func (c *ReceiverConfig) copyIn() {
@@ -475,6 +492,11 @@ func (c *ReceiverConfig) Validate() error {
 	if c.RootWithoutClientComponent.Length() <= 0 {
 		return errors.New("RootWithoutClientComponent must not be an empty dataset path")
 	}
+
+	if err := bandwidthlimit.ValidateConfig(c.BandwidthLimit); err != nil {
+		return errors.Wrap(err, "`Ratelimit` field invalid")
+	}
+
 	return nil
 }
 
@@ -484,6 +506,8 @@ type Receiver struct {
 
 	conf ReceiverConfig // validated
 
+	bwLimit bandwidthlimit.Wrapper
+
 	recvParentCreationMtx *chainlock.L
 }
 
@@ -495,6 +519,7 @@ func NewReceiver(config ReceiverConfig) *Receiver {
 	return &Receiver{
 		conf:                  config,
 		recvParentCreationMtx: chainlock.New(),
+		bwLimit:               bandwidthlimit.WrapperFromConfig(config.BandwidthLimit),
 	}
 }
 
@@ -787,6 +812,9 @@ func (s *Receiver) Receive(ctx context.Context, req *pdu.ReceiveReq, receive io.
 		return nil, errors.Wrap(err, "cannot determine whether we can use resumable send & recv")
 	}
 
+	// apply rate limit
+	receive = s.bwLimit.WrapReadCloser(receive)
+
 	var peek bytes.Buffer
 	var MaxPeek = envconst.Int64("ZREPL_ENDPOINT_RECV_PEEK_SIZE", 1<<20)
 	log.WithField("max_peek_bytes", MaxPeek).Info("peeking incoming stream")

go.mod

@@ -15,6 +15,7 @@ require (
 	github.com/golang/protobuf v1.4.3
 	github.com/google/uuid v1.1.2
 	github.com/jinzhu/copier v0.0.0-20170922082739-db4671f3a9b8
+	github.com/juju/ratelimit v1.0.1
 	github.com/kisielk/gotool v1.0.0 // indirect
 	github.com/kr/pretty v0.1.0
 	github.com/leodido/go-urn v1.2.1 // indirect

go.sum

@@ -164,6 +164,8 @@ github.com/jinzhu/copier v0.0.0-20170922082739-db4671f3a9b8 h1:+dKzeuiDYbD/Cfi/s
 github.com/jinzhu/copier v0.0.0-20170922082739-db4671f3a9b8/go.mod h1:yL958EeXv8Ylng6IfnvG4oflryUi3vgA3xPs9hmII1s=
 github.com/json-iterator/go v1.1.6/go.mod h1:+SdeFBvtyEkXs7REEP0seUULqWtbJapLOCVDaaPEHmU=
 github.com/json-iterator/go v1.1.7/go.mod h1:KdQUCv79m/52Kvf8AW2vK1V8akMuk1QjK/uOdHXbAo4=
+github.com/juju/ratelimit v1.0.1 h1:+7AIFJVQ0EQgq/K9+0Krm7m530Du7tIz0METWzN0RgY=
+github.com/juju/ratelimit v1.0.1/go.mod h1:qapgC/Gy+xNh9UxzV13HGGl/6UXNN+ct+vwSgWNm/qk=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
 github.com/jung-kurt/gofpdf v1.0.3-0.20190309125859-24315acbbda5/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
 github.com/k0kubun/colorstring v0.0.0-20150214042306-9440f1994b88 h1:uC1QfSlInpQF+M0ao65imhwqKnz3Q2z/d8PWZRMQvDM=

util/bandwidthlimit/bandwidthlimit.go

@@ -0,0 +1,72 @@
+package bandwidthlimit
+
+import (
+	"errors"
+	"io"
+
+	"github.com/juju/ratelimit"
+)
+
+type Wrapper interface {
+	WrapReadCloser(io.ReadCloser) io.ReadCloser
+}
+
+type Config struct {
+	// Units in this struct are in _bytes_.
+
+	Max            int64 // < 0 means no limit, BucketCapacity is irrelevant then
+	BucketCapacity int64
+}
+
+func ValidateConfig(conf Config) error {
+	if conf.BucketCapacity == 0 {
+		return errors.New("BucketCapacity must not be zero")
+	}
+	return nil
+}
+
+func WrapperFromConfig(conf Config) Wrapper {
+	if err := ValidateConfig(conf); err != nil {
+		panic(err)
+	}
+
+	if conf.Max < 0 {
+		return noLimit{}
+	}
+
+	return &withLimit{
+		bucket: ratelimit.NewBucketWithRate(float64(conf.Max), conf.BucketCapacity),
+	}
+}
+
+type noLimit struct{}
+
+func (_ noLimit) WrapReadCloser(rc io.ReadCloser) io.ReadCloser { return rc }
+
+type withLimit struct {
+	bucket *ratelimit.Bucket
+}
+
+func (l *withLimit) WrapReadCloser(rc io.ReadCloser) io.ReadCloser {
+	return WrapReadCloser(rc, l.bucket)
+}
+
+type withLimitReadCloser struct {
+	orig    io.Closer
+	limited io.Reader
+}
+
+func (r *withLimitReadCloser) Read(buf []byte) (int, error) {
+	return r.limited.Read(buf)
+}
+
+func (r *withLimitReadCloser) Close() error {
+	return r.orig.Close()
+}
+
+func WrapReadCloser(rc io.ReadCloser, bucket *ratelimit.Bucket) io.ReadCloser {
+	return &withLimitReadCloser{
+		limited: ratelimit.Reader(rc, bucket),
+		orig:    rc,
+	}
+}

util/datasizeunit/datasizeunit.go

@@ -0,0 +1,86 @@
+package datasizeunit
+
+import (
+	"errors"
+	"fmt"
+	"math"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+type Bits struct {
+	bits float64
+}
+
+func (b Bits) ToBits() float64    { return b.bits }
+func (b Bits) ToBytes() float64   { return b.bits / 8 }
+func FromBytesInt64(i int64) Bits { return Bits{float64(i) * 8} }
+
+var datarateRegex = regexp.MustCompile(`^([-0-9\.]*)\s*(bit|(|K|Ki|M|Mi|G|Gi|T|Ti)([bB]))$`)
+
+func (r *Bits) UnmarshalYAML(u func(interface{}, bool) error) (_ error) {
+
+	var s string
+	err := u(&s, false)
+	if err != nil {
+		return err
+	}
+
+	genericErr := func(err error) error {
+		var buf strings.Builder
+		fmt.Fprintf(&buf, "cannot parse %q using regex %s", s, datarateRegex)
+		if err != nil {
+			fmt.Fprintf(&buf, ": %s", err)
+		}
+		return errors.New(buf.String())
+	}
+
+	match := datarateRegex.FindStringSubmatch(s)
+	if match == nil {
+		return genericErr(nil)
+	}
+
+	bps, err := strconv.ParseFloat(match[1], 64)
+	if err != nil {
+		return genericErr(err)
+	}
+
+	if match[2] == "bit" {
+		if math.Round(bps) != bps {
+			return genericErr(fmt.Errorf("unit bit must be an integer value"))
+		}
+		r.bits = bps
+		return nil
+	}
+
+	factorMap := map[string]uint64{
+		"": 1,
+
+		"K": 1e3,
+		"M": 1e6,
+		"G": 1e9,
+		"T": 1e12,
+
+		"Ki": 1 << 10,
+		"Mi": 1 << 20,
+		"Gi": 1 << 30,
+		"Ti": 1 << 40,
+	}
+	factor, ok := factorMap[match[3]]
+	if !ok {
+		panic(match)
+	}
+
+	baseUnitFactorMap := map[string]uint64{
+		"b": 1,
+		"B": 8,
+	}
+	baseUnitFactor, ok := baseUnitFactorMap[match[4]]
+	if !ok {
+		panic(match)
+	}
+
+	r.bits = bps * float64(factor) * float64(baseUnitFactor)
+	return nil
+}

util/datasizeunit/datasizeunit_test.go

@@ -0,0 +1,57 @@
+package datasizeunit
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/zrepl/yaml-config"
+)
+
+func TestBits(t *testing.T) {
+
+	tcs := []struct {
+		input      string
+		expectRate float64
+		expectErr  string
+	}{
+		{`23 bit`, 23, ""}, // bit special case works
+		{`23bit`, 23, ""},  // also without space
+
+		{`10MiB`, 10 * (1 << 20) * 8, ""},  // integer unit without space
+		{`10 MiB`, 8 * 10 * (1 << 20), ""}, // integer unit with space
+
+		{`10.5 Kib`, 10.5 * (1 << 10), ""}, // floating point with bit unit works with space
+		{`10.5Kib`, 10.5 * (1 << 10), ""},  // floating point with bit unit works without space
+
+		// unit checks
+		{`1 bit`, 1, ""},
+		{`1 B`, 1 * 8, ""},
+		{`1 Kb`, 1e3, ""},
+		{`1 Kib`, 1 << 10, ""},
+		{`1 Mb`, 1e6, ""},
+		{`1 Mib`, 1 << 20, ""},
+		{`1 Gb`, 1e9, ""},
+		{`1 Gib`, 1 << 30, ""},
+		{`1 Tb`, 1e12, ""},
+		{`1 Tib`, 1 << 40, ""},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.input, func(t *testing.T) {
+
+			var bits Bits
+			err := yaml.Unmarshal([]byte(tc.input), &bits)
+			if tc.expectErr != "" {
+				assert.Error(t, err)
+				assert.Regexp(t, tc.expectErr, err.Error())
+				assert.Zero(t, bits.bits)
+			} else {
+				require.NoError(t, err)
+				assert.Equal(t, tc.expectRate, bits.bits)
+			}
+		})
+
+	}
+
+}