open-vault/physical/raft/raft_test.go

package raft

import (
	"bytes"
	"context"
	"crypto/md5"
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"io"
	"io/ioutil"
	"math/rand"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/go-test/deep"
	"github.com/golang/protobuf/proto"
	"github.com/hashicorp/go-hclog"
	"github.com/hashicorp/go-secure-stdlib/base62"
	"github.com/hashicorp/go-uuid"
	"github.com/hashicorp/raft"
	"github.com/hashicorp/vault/sdk/helper/jsonutil"
	"github.com/hashicorp/vault/sdk/physical"
	bolt "go.etcd.io/bbolt"
)

func getRaft(t testing.TB, bootstrap bool, noStoreState bool) (*RaftBackend, string) {
	raftDir, err := ioutil.TempDir("", "vault-raft-")
	if err != nil {
		t.Fatal(err)
	}
	t.Logf("raft dir: %s", raftDir)

	return getRaftWithDir(t, bootstrap, noStoreState, raftDir)
}

func getRaftWithDir(t testing.TB, bootstrap bool, noStoreState bool, raftDir string) (*RaftBackend, string) {
	id, err := uuid.GenerateUUID()
	if err != nil {
		t.Fatal(err)
	}

	logger := hclog.New(&hclog.LoggerOptions{
		Name:  fmt.Sprintf("raft-%s", id),
		Level: hclog.Trace,
	})
	logger.Info("raft dir", "dir", raftDir)

	conf := map[string]string{
		"path":          raftDir,
		"trailing_logs": "100",
		"node_id":       id,
	}

	if noStoreState {
		conf["doNotStoreLatestState"] = ""
	}

	backendRaw, err := NewRaftBackend(conf, logger)
	if err != nil {
		t.Fatal(err)
	}
	backend := backendRaw.(*RaftBackend)

	if bootstrap {
		err = backend.Bootstrap([]Peer{
			{
				ID:      backend.NodeID(),
				Address: backend.NodeID(),
			},
		})
		if err != nil {
			t.Fatal(err)
		}

		err = backend.SetupCluster(context.Background(), SetupOpts{})
		if err != nil {
			t.Fatal(err)
		}

		for {
			if backend.raft.AppliedIndex() >= 2 {
				break
			}
		}

	}

	backend.DisableAutopilot()

	return backend, raftDir
}

func connectPeers(nodes ...*RaftBackend) {
	for _, node := range nodes {
		for _, peer := range nodes {
			if node == peer {
				continue
			}

			node.raftTransport.(*raft.InmemTransport).Connect(raft.ServerAddress(peer.NodeID()), peer.raftTransport)
			peer.raftTransport.(*raft.InmemTransport).Connect(raft.ServerAddress(node.NodeID()), node.raftTransport)
		}
	}
}

func stepDownLeader(t *testing.T, node *RaftBackend) {
	t.Helper()

	if err := node.raft.LeadershipTransfer().Error(); err != nil {
		t.Fatal(err)
	}

	timeout := time.Now().Add(time.Second * 10)
	for !time.Now().After(timeout) {
		if err := node.raft.VerifyLeader().Error(); err != nil {
			return
		}
		time.Sleep(100 * time.Millisecond)
	}

	t.Fatal("still leader")
}

func waitForLeader(t *testing.T, nodes ...*RaftBackend) *RaftBackend {
	t.Helper()
	timeout := time.Now().Add(time.Second * 10)
	for !time.Now().After(timeout) {
		for _, node := range nodes {
			if node.raft.Leader() == raft.ServerAddress(node.NodeID()) {
				return node
			}
		}
		time.Sleep(100 * time.Millisecond)
	}

	t.Fatal("no leader")
	return nil
}

func compareFSMs(t *testing.T, fsm1, fsm2 *FSM) {
	t.Helper()
	if err := compareFSMsWithErr(t, fsm1, fsm2); err != nil {
		t.Fatal(err)
	}
}

func compareFSMsWithErr(t *testing.T, fsm1, fsm2 *FSM) error {
	t.Helper()
	index1, config1 := fsm1.LatestState()
	index2, config2 := fsm2.LatestState()

	if !proto.Equal(index1, index2) {
		return fmt.Errorf("indexes did not match: %+v != %+v", index1, index2)
	}
	if !proto.Equal(config1, config2) {
		return fmt.Errorf("configs did not match: %+v != %+v", config1, config2)
	}

	return compareDBs(t, fsm1.getDB(), fsm2.getDB(), false)
}

func compareDBs(t *testing.T, boltDB1, boltDB2 *bolt.DB, dataOnly bool) error {
	t.Helper()
	db1 := make(map[string]string)
	db2 := make(map[string]string)

	err := boltDB1.View(func(tx *bolt.Tx) error {
		c := tx.Cursor()
		for bucketName, _ := c.First(); bucketName != nil; bucketName, _ = c.Next() {
			if dataOnly && !bytes.Equal(bucketName, dataBucketName) {
				continue
			}

			b := tx.Bucket(bucketName)

			cBucket := b.Cursor()

			for k, v := cBucket.First(); k != nil; k, v = cBucket.Next() {
				db1[string(k)] = base64.StdEncoding.EncodeToString(v)
			}
		}

		return nil
	})
	if err != nil {
		t.Fatal(err)
	}

	err = boltDB2.View(func(tx *bolt.Tx) error {
		c := tx.Cursor()
		for bucketName, _ := c.First(); bucketName != nil; bucketName, _ = c.Next() {
			if dataOnly && !bytes.Equal(bucketName, dataBucketName) {
				continue
			}
			b := tx.Bucket(bucketName)

			c := b.Cursor()

			for k, v := c.First(); k != nil; k, v = c.Next() {
				db2[string(k)] = base64.StdEncoding.EncodeToString(v)
			}
		}

		return nil
	})

	if err != nil {
		t.Fatal(err)
	}

	if diff := deep.Equal(db1, db2); diff != nil {
		return fmt.Errorf("%+v", diff)
	}

	return nil
}

func TestRaft_Backend(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	physical.ExerciseBackend(t, b)
}

func TestRaft_ParseAutopilotUpgradeVersion(t *testing.T) {
	raftDir, err := ioutil.TempDir("", "vault-raft-")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(raftDir)

	conf := map[string]string{
		"path":                      raftDir,
		"node_id":                   "abc123",
		"autopilot_upgrade_version": "hahano",
	}

	_, err = NewRaftBackend(conf, hclog.NewNullLogger())
	if err == nil {
		t.Fatal("expected an error but got none")
	}

	if !strings.Contains(err.Error(), "does not parse") {
		t.Fatal("expected an error about unparseable versions but got none")
	}
}

func TestRaft_ParseNonVoter(t *testing.T) {
	p := func(s string) *string {
		return &s
	}

	for _, retryJoinConf := range []string{"", "not-empty"} {
		t.Run(retryJoinConf, func(t *testing.T) {
			for name, tc := range map[string]struct {
				envValue             *string
				configValue          *string
				expectNonVoter       bool
				invalidNonVoterValue bool
			}{
				"valid false":                {nil, p("false"), false, false},
				"valid true":                 {nil, p("true"), true, false},
				"invalid empty":              {nil, p(""), false, true},
				"invalid truthy":             {nil, p("no"), false, true},
				"invalid":                    {nil, p("totallywrong"), false, true},
				"valid env false":            {p("false"), nil, true, false},
				"valid env true":             {p("true"), nil, true, false},
				"valid env not boolean":      {p("anything"), nil, true, false},
				"valid env empty":            {p(""), nil, false, false},
				"neither set, default false": {nil, nil, false, false},
				"both set, env preferred":    {p("true"), p("false"), true, false},
			} {
				t.Run(name, func(t *testing.T) {
					if tc.envValue != nil {
						t.Setenv(EnvVaultRaftNonVoter, *tc.envValue)
					}
					raftDir, err := ioutil.TempDir("", "vault-raft-")
					if err != nil {
						t.Fatal(err)
					}
					defer os.RemoveAll(raftDir)

					conf := map[string]string{
						"path":       raftDir,
						"node_id":    "abc123",
						"retry_join": retryJoinConf,
					}
					if tc.configValue != nil {
						conf[raftNonVoterConfigKey] = *tc.configValue
					}

					backend, err := NewRaftBackend(conf, hclog.NewNullLogger())
					switch {
					case tc.invalidNonVoterValue || (retryJoinConf == "" && tc.expectNonVoter):
						if err == nil {
							t.Fatal("expected an error but got none")
						}
					default:
						if err != nil {
							t.Fatalf("expected no error but got: %s", err)
						}

						raftBackend := backend.(*RaftBackend)
						if tc.expectNonVoter != raftBackend.NonVoter() {
							t.Fatalf("expected %s %v but got %v", raftNonVoterConfigKey, tc.expectNonVoter, raftBackend.NonVoter())
						}
					}
				})
			}
		})
	}
}

func TestRaft_Backend_LargeKey(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	key, err := base62.Random(bolt.MaxKeySize + 1)
	if err != nil {
		t.Fatal(err)
	}
	entry := &physical.Entry{Key: key, Value: []byte(key)}

	err = b.Put(context.Background(), entry)
	if err == nil {
		t.Fatal("expected error for put entry")
	}

	if !strings.Contains(err.Error(), physical.ErrKeyTooLarge) {
		t.Fatalf("expected %q, got %v", physical.ErrKeyTooLarge, err)
	}

	out, err := b.Get(context.Background(), entry.Key)
	if err != nil {
		t.Fatalf("unexpected error after failed put: %v", err)
	}
	if out != nil {
		t.Fatal("expected response entry to be nil after a failed put")
	}
}

func TestRaft_Backend_LargeValue(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	value := make([]byte, defaultMaxEntrySize+1)
	rand.Read(value)
	entry := &physical.Entry{Key: "foo", Value: value}

	err := b.Put(context.Background(), entry)
	if err == nil {
		t.Fatal("expected error for put entry")
	}

	if !strings.Contains(err.Error(), physical.ErrValueTooLarge) {
		t.Fatalf("expected %q, got %v", physical.ErrValueTooLarge, err)
	}

	out, err := b.Get(context.Background(), entry.Key)
	if err != nil {
		t.Fatalf("unexpected error after failed put: %v", err)
	}
	if out != nil {
		t.Fatal("expected response entry to be nil after a failed put")
	}
}

// TestRaft_TransactionalBackend_GetTransactions tests that passing a slice of transactions to the
// raft backend will populate values for any transactions that are Get operations.
func TestRaft_TransactionalBackend_GetTransactions(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	ctx := context.Background()
	txns := make([]*physical.TxnEntry, 0)

	// Add some seed values to our FSM, and prepare our slice of transactions at the same time
	for i := 0; i < 5; i++ {
		key := fmt.Sprintf("foo/%d", i)
		err := b.fsm.Put(ctx, &physical.Entry{Key: key, Value: []byte(fmt.Sprintf("value-%d", i))})
		if err != nil {
			t.Fatal(err)
		}

		txns = append(txns, &physical.TxnEntry{
			Operation: physical.GetOperation,
			Entry: &physical.Entry{
				Key: key,
			},
		})
	}

	// Add some additional transactions, so we have a mix of operations
	for i := 0; i < 10; i++ {
		txnEntry := &physical.TxnEntry{
			Entry: &physical.Entry{
				Key: fmt.Sprintf("lol-%d", i),
			},
		}

		if i%2 == 0 {
			txnEntry.Operation = physical.PutOperation
			txnEntry.Entry.Value = []byte("lol")
		} else {
			txnEntry.Operation = physical.DeleteOperation
		}

		txns = append(txns, txnEntry)
	}

	err := b.Transaction(ctx, txns)
	if err != nil {
		t.Fatal(err)
	}

	// Check that our Get operations were populated with their values
	for i, txn := range txns {
		if txn.Operation == physical.GetOperation {
			val := []byte(fmt.Sprintf("value-%d", i))
			if !bytes.Equal(val, txn.Entry.Value) {
				t.Fatalf("expected %s to equal %s but it didn't", hex.EncodeToString(val), hex.EncodeToString(txn.Entry.Value))
			}
		}
	}
}

func TestRaft_TransactionalBackend_LargeKey(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	value := make([]byte, defaultMaxEntrySize+1)
	rand.Read(value)

	key, err := base62.Random(bolt.MaxKeySize + 1)
	if err != nil {
		t.Fatal(err)
	}
	txns := []*physical.TxnEntry{
		{
			Operation: physical.PutOperation,
			Entry: &physical.Entry{
				Key:   key,
				Value: []byte(key),
			},
		},
	}

	err = b.Transaction(context.Background(), txns)
	if err == nil {
		t.Fatal("expected error for transactions")
	}

	if !strings.Contains(err.Error(), physical.ErrKeyTooLarge) {
		t.Fatalf("expected %q, got %v", physical.ErrValueTooLarge, err)
	}

	out, err := b.Get(context.Background(), txns[0].Entry.Key)
	if err != nil {
		t.Fatalf("unexpected error after failed put: %v", err)
	}
	if out != nil {
		t.Fatal("expected response entry to be nil after a failed put")
	}
}

func TestRaft_TransactionalBackend_LargeValue(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	value := make([]byte, defaultMaxEntrySize+1)
	rand.Read(value)

	txns := []*physical.TxnEntry{
		{
			Operation: physical.PutOperation,
			Entry: &physical.Entry{
				Key:   "foo",
				Value: value,
			},
		},
	}

	err := b.Transaction(context.Background(), txns)
	if err == nil {
		t.Fatal("expected error for transactions")
	}

	if !strings.Contains(err.Error(), physical.ErrValueTooLarge) {
		t.Fatalf("expected %q, got %v", physical.ErrValueTooLarge, err)
	}

	out, err := b.Get(context.Background(), txns[0].Entry.Key)
	if err != nil {
		t.Fatalf("unexpected error after failed put: %v", err)
	}
	if out != nil {
		t.Fatal("expected response entry to be nil after a failed put")
	}
}

func TestRaft_Backend_ListPrefix(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	physical.ExerciseBackend_ListPrefix(t, b)
}

func TestRaft_TransactionalBackend(t *testing.T) {
	b, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)

	physical.ExerciseTransactionalBackend(t, b)
}

func TestRaft_HABackend(t *testing.T) {
	t.Skip()
	raft, dir := getRaft(t, true, true)
	defer os.RemoveAll(dir)
	raft2, dir2 := getRaft(t, false, true)
	defer os.RemoveAll(dir2)

	// Add raft2 to the cluster
	addPeer(t, raft, raft2)

	physical.ExerciseHABackend(t, raft, raft2)
}

func TestRaft_Backend_ThreeNode(t *testing.T) {
	raft1, dir := getRaft(t, true, true)
	raft2, dir2 := getRaft(t, false, true)
	raft3, dir3 := getRaft(t, false, true)
	defer os.RemoveAll(dir)
	defer os.RemoveAll(dir2)
	defer os.RemoveAll(dir3)

	// Add raft2 to the cluster
	addPeer(t, raft1, raft2)

	// Add raft3 to the cluster
	addPeer(t, raft1, raft3)

	physical.ExerciseBackend(t, raft1)

	time.Sleep(10 * time.Second)
	// Make sure all stores are the same
	compareFSMs(t, raft1.fsm, raft2.fsm)
	compareFSMs(t, raft1.fsm, raft3.fsm)
}

func TestRaft_GetOfflineConfig(t *testing.T) {
	// Create 3 raft nodes
	raft1, dir1 := getRaft(t, true, true)
	raft2, dir2 := getRaft(t, false, true)
	raft3, dir3 := getRaft(t, false, true)
	defer os.RemoveAll(dir1)
	defer os.RemoveAll(dir2)
	defer os.RemoveAll(dir3)

	// Add them all to the cluster
	addPeer(t, raft1, raft2)
	addPeer(t, raft1, raft3)

	// Add some data into the FSM
	physical.ExerciseBackend(t, raft1)

	time.Sleep(10 * time.Second)

	// Spin down the raft cluster and check that GetConfigurationOffline
	// returns 3 voters
	raft3.TeardownCluster(nil)
	raft2.TeardownCluster(nil)
	raft1.TeardownCluster(nil)

	conf, err := raft1.GetConfigurationOffline()
	if err != nil {
		t.Fatal(err)
	}
	if len(conf.Servers) != 3 {
		t.Fatalf("three raft nodes existed but we only see %d", len(conf.Servers))
	}
	for _, s := range conf.Servers {
		if s.Voter != true {
			t.Fatalf("one of the nodes is not a voter")
		}
	}
}

func TestRaft_Recovery(t *testing.T) {
	// Create 4 raft nodes
	raft1, dir1 := getRaft(t, true, true)
	raft2, dir2 := getRaft(t, false, true)
	raft3, dir3 := getRaft(t, false, true)
	raft4, dir4 := getRaft(t, false, true)
	defer os.RemoveAll(dir1)
	defer os.RemoveAll(dir2)
	defer os.RemoveAll(dir3)
	defer os.RemoveAll(dir4)

	// Add them all to the cluster
	addPeer(t, raft1, raft2)
	addPeer(t, raft1, raft3)
	addPeer(t, raft1, raft4)

	// Add some data into the FSM
	physical.ExerciseBackend(t, raft1)

	time.Sleep(10 * time.Second)

	// Bring down all nodes
	raft1.TeardownCluster(nil)
	raft2.TeardownCluster(nil)
	raft3.TeardownCluster(nil)
	raft4.TeardownCluster(nil)

	// Prepare peers.json
	type RecoveryPeer struct {
		ID       string `json:"id"`
		Address  string `json:"address"`
		NonVoter bool   `json:"non_voter"`
	}

	// Leave out node 1 during recovery
	peersList := make([]*RecoveryPeer, 0, 3)
	peersList = append(peersList, &RecoveryPeer{
		ID:       raft1.NodeID(),
		Address:  raft1.NodeID(),
		NonVoter: false,
	})
	peersList = append(peersList, &RecoveryPeer{
		ID:       raft2.NodeID(),
		Address:  raft2.NodeID(),
		NonVoter: false,
	})
	peersList = append(peersList, &RecoveryPeer{
		ID:       raft4.NodeID(),
		Address:  raft4.NodeID(),
		NonVoter: false,
	})

	peersJSONBytes, err := jsonutil.EncodeJSON(peersList)
	if err != nil {
		t.Fatal(err)
	}
	err = ioutil.WriteFile(filepath.Join(filepath.Join(dir1, raftState), "peers.json"), peersJSONBytes, 0o644)
	if err != nil {
		t.Fatal(err)
	}
	err = ioutil.WriteFile(filepath.Join(filepath.Join(dir2, raftState), "peers.json"), peersJSONBytes, 0o644)
	if err != nil {
		t.Fatal(err)
	}
	err = ioutil.WriteFile(filepath.Join(filepath.Join(dir4, raftState), "peers.json"), peersJSONBytes, 0o644)
	if err != nil {
		t.Fatal(err)
	}

	// Bring up the nodes again
	raft1.SetupCluster(context.Background(), SetupOpts{})
	raft2.SetupCluster(context.Background(), SetupOpts{})
	raft4.SetupCluster(context.Background(), SetupOpts{})

	peers, err := raft1.Peers(context.Background())
	if err != nil {
		t.Fatal(err)
	}
	if len(peers) != 3 {
		t.Fatalf("failed to recover the cluster")
	}

	time.Sleep(10 * time.Second)

	compareFSMs(t, raft1.fsm, raft2.fsm)
	compareFSMs(t, raft1.fsm, raft4.fsm)
}

func TestRaft_TransactionalBackend_ThreeNode(t *testing.T) {
	raft1, dir := getRaft(t, true, true)
	raft2, dir2 := getRaft(t, false, true)
	raft3, dir3 := getRaft(t, false, true)
	defer os.RemoveAll(dir)
	defer os.RemoveAll(dir2)
	defer os.RemoveAll(dir3)

	// Add raft2 to the cluster
	addPeer(t, raft1, raft2)

	// Add raft3 to the cluster
	addPeer(t, raft1, raft3)

	physical.ExerciseTransactionalBackend(t, raft1)

	time.Sleep(10 * time.Second)
	// Make sure all stores are the same
	compareFSMs(t, raft1.fsm, raft2.fsm)
	compareFSMs(t, raft1.fsm, raft3.fsm)
}

func TestRaft_Backend_Performance(t *testing.T) {
	b, dir := getRaft(t, true, false)
	defer os.RemoveAll(dir)

	defaultConfig := raft.DefaultConfig()

	localConfig := raft.DefaultConfig()
	b.applyConfigSettings(localConfig)

	if localConfig.ElectionTimeout != defaultConfig.ElectionTimeout*5 {
		t.Fatalf("bad config: %v", localConfig)
	}
	if localConfig.HeartbeatTimeout != defaultConfig.HeartbeatTimeout*5 {
		t.Fatalf("bad config: %v", localConfig)
	}
	if localConfig.LeaderLeaseTimeout != defaultConfig.LeaderLeaseTimeout*5 {
		t.Fatalf("bad config: %v", localConfig)
	}

	b.conf = map[string]string{
		"path":                   dir,
		"performance_multiplier": "5",
	}

	localConfig = raft.DefaultConfig()
	b.applyConfigSettings(localConfig)

	if localConfig.ElectionTimeout != defaultConfig.ElectionTimeout*5 {
		t.Fatalf("bad config: %v", localConfig)
	}
	if localConfig.HeartbeatTimeout != defaultConfig.HeartbeatTimeout*5 {
		t.Fatalf("bad config: %v", localConfig)
	}
	if localConfig.LeaderLeaseTimeout != defaultConfig.LeaderLeaseTimeout*5 {
		t.Fatalf("bad config: %v", localConfig)
	}

	b.conf = map[string]string{
		"path":                   dir,
		"performance_multiplier": "1",
	}

	localConfig = raft.DefaultConfig()
	b.applyConfigSettings(localConfig)

	if localConfig.ElectionTimeout != defaultConfig.ElectionTimeout {
		t.Fatalf("bad config: %v", localConfig)
	}
	if localConfig.HeartbeatTimeout != defaultConfig.HeartbeatTimeout {
		t.Fatalf("bad config: %v", localConfig)
	}
	if localConfig.LeaderLeaseTimeout != defaultConfig.LeaderLeaseTimeout {
		t.Fatalf("bad config: %v", localConfig)
	}
}

func BenchmarkDB_Puts(b *testing.B) {
	raft, dir := getRaft(b, true, false)
	defer os.RemoveAll(dir)
	raft2, dir2 := getRaft(b, true, false)
	defer os.RemoveAll(dir2)

	bench := func(b *testing.B, s physical.Backend, dataSize int) {
		data, err := uuid.GenerateRandomBytes(dataSize)
		if err != nil {
			b.Fatal(err)
		}

		ctx := context.Background()
		pe := &physical.Entry{
			Value: data,
		}
		testName := b.Name()

		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			pe.Key = fmt.Sprintf("%x", md5.Sum([]byte(fmt.Sprintf("%s-%d", testName, i))))
			err := s.Put(ctx, pe)
			if err != nil {
				b.Fatal(err)
			}
		}
	}

	b.Run("256b", func(b *testing.B) { bench(b, raft, 256) })
	b.Run("256kb", func(b *testing.B) { bench(b, raft2, 256*1024) })
}

func BenchmarkDB_Snapshot(b *testing.B) {
	raft, dir := getRaft(b, true, false)
	defer os.RemoveAll(dir)

	data, err := uuid.GenerateRandomBytes(256 * 1024)
	if err != nil {
		b.Fatal(err)
	}

	ctx := context.Background()
	pe := &physical.Entry{
		Value: data,
	}
	testName := b.Name()

	for i := 0; i < 100; i++ {
		pe.Key = fmt.Sprintf("%x", md5.Sum([]byte(fmt.Sprintf("%s-%d", testName, i))))
		err = raft.Put(ctx, pe)
		if err != nil {
			b.Fatal(err)
		}
	}

	bench := func(b *testing.B, s *FSM) {
		b.ResetTimer()
		for i := 0; i < b.N; i++ {
			pe.Key = fmt.Sprintf("%x", md5.Sum([]byte(fmt.Sprintf("%s-%d", testName, i))))
			s.writeTo(ctx, discardCloser{Writer: ioutil.Discard}, discardCloser{Writer: ioutil.Discard})
		}
	}

	b.Run("256kb", func(b *testing.B) { bench(b, raft.fsm) })
}

type discardCloser struct {
	io.Writer
}

func (d discardCloser) Close() error               { return nil }
func (d discardCloser) CloseWithError(error) error { return nil }