diff --git a/vendor/go.etcd.io/bbolt/tx_check.go b/vendor/go.etcd.io/bbolt/tx_check.go
new file mode 100644
index 0000000..c3ecbb9
--- /dev/null
+++ b/vendor/go.etcd.io/bbolt/tx_check.go
@@ -0,0 +1,290 @@
+package bbolt
+
+import (
+	"encoding/hex"
+	"fmt"
+
+	"go.etcd.io/bbolt/internal/common"
+)
+
+// Check performs several consistency checks on the database for this transaction.
+// An error is returned if any inconsistency is found.
+//
+// It can be safely run concurrently on a writable transaction. However, this
+// incurs a high cost for large databases and databases with a lot of subbuckets
+// because of caching. This overhead can be removed if running on a read-only
+// transaction, however, it is not safe to execute other writer transactions at
+// the same time.
+//
+// It also allows users to provide a customized `KVStringer` implementation,
+// so that bolt can generate human-readable diagnostic messages.
+func (tx *Tx) Check(options ...CheckOption) <-chan error {
+	chkConfig := checkConfig{
+		kvStringer: HexKVStringer(),
+	}
+	for _, op := range options {
+		op(&chkConfig)
+	}
+
+	ch := make(chan error)
+	go func() {
+		// Close the channel to signal completion.
+		defer close(ch)
+		tx.check(chkConfig, ch)
+	}()
+	return ch
+}
+
+func (tx *Tx) check(cfg checkConfig, ch chan error) {
+	// Force loading free list if opened in ReadOnly mode.
+	tx.db.loadFreelist()
+
+	// Check if any pages are double freed.
+	freed := make(map[common.Pgid]bool)
+	all := make([]common.Pgid, tx.db.freelist.Count())
+	tx.db.freelist.Copyall(all)
+	for _, id := range all {
+		if freed[id] {
+			ch <- fmt.Errorf("page %d: already freed", id)
+		}
+		freed[id] = true
+	}
+
+	// Track every reachable page.
+	reachable := make(map[common.Pgid]*common.Page)
+	reachable[0] = tx.page(0) // meta0
+	reachable[1] = tx.page(1) // meta1
+	if tx.meta.Freelist() != common.PgidNoFreelist {
+		for i := uint32(0); i <= tx.page(tx.meta.Freelist()).Overflow(); i++ {
+			reachable[tx.meta.Freelist()+common.Pgid(i)] = tx.page(tx.meta.Freelist())
+		}
+	}
+
+	if cfg.pageId == 0 {
+		// Check the whole db file, starting from the root bucket and
+		// recursively check all child buckets.
+		tx.recursivelyCheckBucket(&tx.root, reachable, freed, cfg.kvStringer, ch)
+
+		// Ensure all pages below high water mark are either reachable or freed.
+		for i := common.Pgid(0); i < tx.meta.Pgid(); i++ {
+			_, isReachable := reachable[i]
+			if !isReachable && !freed[i] {
+				ch <- fmt.Errorf("page %d: unreachable unfreed", int(i))
+			}
+		}
+	} else {
+		// Check the db file starting from a specified pageId.
+		if cfg.pageId < 2 || cfg.pageId >= uint64(tx.meta.Pgid()) {
+			ch <- fmt.Errorf("page ID (%d) out of range [%d, %d)", cfg.pageId, 2, tx.meta.Pgid())
+			return
+		}
+
+		tx.recursivelyCheckPage(common.Pgid(cfg.pageId), reachable, freed, cfg.kvStringer, ch)
+	}
+}
+
+func (tx *Tx) recursivelyCheckPage(pageId common.Pgid, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool,
+	kvStringer KVStringer, ch chan error) {
+	tx.checkInvariantProperties(pageId, reachable, freed, kvStringer, ch)
+	tx.recursivelyCheckBucketInPage(pageId, reachable, freed, kvStringer, ch)
+}
+
+func (tx *Tx) recursivelyCheckBucketInPage(pageId common.Pgid, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool,
+	kvStringer KVStringer, ch chan error) {
+	p := tx.page(pageId)
+
+	switch {
+	case p.IsBranchPage():
+		for i := range p.BranchPageElements() {
+			elem := p.BranchPageElement(uint16(i))
+			tx.recursivelyCheckBucketInPage(elem.Pgid(), reachable, freed, kvStringer, ch)
+		}
+	case p.IsLeafPage():
+		for i := range p.LeafPageElements() {
+			elem := p.LeafPageElement(uint16(i))
+			if elem.IsBucketEntry() {
+				inBkt := common.NewInBucket(pageId, 0)
+				tmpBucket := Bucket{
+					InBucket:    &inBkt,
+					rootNode:    &node{isLeaf: p.IsLeafPage()},
+					FillPercent: DefaultFillPercent,
+					tx:          tx,
+				}
+				if child := tmpBucket.Bucket(elem.Key()); child != nil {
+					tx.recursivelyCheckBucket(child, reachable, freed, kvStringer, ch)
+				}
+			}
+		}
+	default:
+		ch <- fmt.Errorf("unexpected page type (flags: %x) for pgId:%d", p.Flags(), pageId)
+	}
+}
+
+func (tx *Tx) recursivelyCheckBucket(b *Bucket, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool,
+	kvStringer KVStringer, ch chan error) {
+	// Ignore inline buckets.
+	if b.RootPage() == 0 {
+		return
+	}
+
+	tx.checkInvariantProperties(b.RootPage(), reachable, freed, kvStringer, ch)
+
+	// Check each bucket within this bucket.
+	_ = b.ForEachBucket(func(k []byte) error {
+		if child := b.Bucket(k); child != nil {
+			tx.recursivelyCheckBucket(child, reachable, freed, kvStringer, ch)
+		}
+		return nil
+	})
+}
+
+func (tx *Tx) checkInvariantProperties(pageId common.Pgid, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool,
+	kvStringer KVStringer, ch chan error) {
+	tx.forEachPage(pageId, func(p *common.Page, _ int, stack []common.Pgid) {
+		verifyPageReachable(p, tx.meta.Pgid(), stack, reachable, freed, ch)
+	})
+
+	tx.recursivelyCheckPageKeyOrder(pageId, kvStringer.KeyToString, ch)
+}
+
+func verifyPageReachable(p *common.Page, hwm common.Pgid, stack []common.Pgid, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool, ch chan error) {
+	if p.Id() > hwm {
+		ch <- fmt.Errorf("page %d: out of bounds: %d (stack: %v)", int(p.Id()), int(hwm), stack)
+	}
+
+	// Ensure each page is only referenced once.
+	for i := common.Pgid(0); i <= common.Pgid(p.Overflow()); i++ {
+		var id = p.Id() + i
+		if _, ok := reachable[id]; ok {
+			ch <- fmt.Errorf("page %d: multiple references (stack: %v)", int(id), stack)
+		}
+		reachable[id] = p
+	}
+
+	// We should only encounter un-freed leaf and branch pages.
+	if freed[p.Id()] {
+		ch <- fmt.Errorf("page %d: reachable freed", int(p.Id()))
+	} else if !p.IsBranchPage() && !p.IsLeafPage() {
+		ch <- fmt.Errorf("page %d: invalid type: %s (stack: %v)", int(p.Id()), p.Typ(), stack)
+	}
+}
+
+// recursivelyCheckPageKeyOrder verifies database consistency with respect to b-tree
+// key order constraints:
+//   - keys on pages must be sorted
+//   - keys on children pages are between 2 consecutive keys on the parent's branch page).
+func (tx *Tx) recursivelyCheckPageKeyOrder(pgId common.Pgid, keyToString func([]byte) string, ch chan error) {
+	tx.recursivelyCheckPageKeyOrderInternal(pgId, nil, nil, nil, keyToString, ch)
+}
+
+// recursivelyCheckPageKeyOrderInternal verifies that all keys in the subtree rooted at `pgid` are:
+//   - >=`minKeyClosed` (can be nil)
+//   - <`maxKeyOpen` (can be nil)
+//   - Are in right ordering relationship to their parents.
+//     `pagesStack` is expected to contain IDs of pages from the tree root to `pgid` for the clean debugging message.
+func (tx *Tx) recursivelyCheckPageKeyOrderInternal(
+	pgId common.Pgid, minKeyClosed, maxKeyOpen []byte, pagesStack []common.Pgid,
+	keyToString func([]byte) string, ch chan error) (maxKeyInSubtree []byte) {
+
+	p := tx.page(pgId)
+	pagesStack = append(pagesStack, pgId)
+	switch {
+	case p.IsBranchPage():
+		// For branch page we navigate ranges of all subpages.
+		runningMin := minKeyClosed
+		for i := range p.BranchPageElements() {
+			elem := p.BranchPageElement(uint16(i))
+			verifyKeyOrder(elem.Pgid(), "branch", i, elem.Key(), runningMin, maxKeyOpen, ch, keyToString, pagesStack)
+
+			maxKey := maxKeyOpen
+			if i < len(p.BranchPageElements())-1 {
+				maxKey = p.BranchPageElement(uint16(i + 1)).Key()
+			}
+			maxKeyInSubtree = tx.recursivelyCheckPageKeyOrderInternal(elem.Pgid(), elem.Key(), maxKey, pagesStack, keyToString, ch)
+			runningMin = maxKeyInSubtree
+		}
+		return maxKeyInSubtree
+	case p.IsLeafPage():
+		runningMin := minKeyClosed
+		for i := range p.LeafPageElements() {
+			elem := p.LeafPageElement(uint16(i))
+			verifyKeyOrder(pgId, "leaf", i, elem.Key(), runningMin, maxKeyOpen, ch, keyToString, pagesStack)
+			runningMin = elem.Key()
+		}
+		if p.Count() > 0 {
+			return p.LeafPageElement(p.Count() - 1).Key()
+		}
+	default:
+		ch <- fmt.Errorf("unexpected page type (flags: %x) for pgId:%d", p.Flags(), pgId)
+	}
+	return maxKeyInSubtree
+}
+
+/***
+ * verifyKeyOrder checks whether an entry with given #index on pgId (pageType: "branch|leaf") that has given "key",
+ * is within range determined by (previousKey..maxKeyOpen) and reports found violations to the channel (ch).
+ */
+func verifyKeyOrder(pgId common.Pgid, pageType string, index int, key []byte, previousKey []byte, maxKeyOpen []byte, ch chan error, keyToString func([]byte) string, pagesStack []common.Pgid) {
+	if index == 0 && previousKey != nil && compareKeys(previousKey, key) > 0 {
+		ch <- fmt.Errorf("the first key[%d]=(hex)%s on %s page(%d) needs to be >= the key in the ancestor (%s). Stack: %v",
+			index, keyToString(key), pageType, pgId, keyToString(previousKey), pagesStack)
+	}
+	if index > 0 {
+		cmpRet := compareKeys(previousKey, key)
+		if cmpRet > 0 {
+			ch <- fmt.Errorf("key[%d]=(hex)%s on %s page(%d) needs to be > (found <) than previous element (hex)%s. Stack: %v",
+				index, keyToString(key), pageType, pgId, keyToString(previousKey), pagesStack)
+		}
+		if cmpRet == 0 {
+			ch <- fmt.Errorf("key[%d]=(hex)%s on %s page(%d) needs to be > (found =) than previous element (hex)%s. Stack: %v",
+				index, keyToString(key), pageType, pgId, keyToString(previousKey), pagesStack)
+		}
+	}
+	if maxKeyOpen != nil && compareKeys(key, maxKeyOpen) >= 0 {
+		ch <- fmt.Errorf("key[%d]=(hex)%s on %s page(%d) needs to be < than key of the next element in ancestor (hex)%s. Pages stack: %v",
+			index, keyToString(key), pageType, pgId, keyToString(previousKey), pagesStack)
+	}
+}
+
+// ===========================================================================================
+
+type checkConfig struct {
+	kvStringer KVStringer
+	pageId     uint64
+}
+
+type CheckOption func(options *checkConfig)
+
+func WithKVStringer(kvStringer KVStringer) CheckOption {
+	return func(c *checkConfig) {
+		c.kvStringer = kvStringer
+	}
+}
+
+// WithPageId sets a page ID from which the check command starts to check
+func WithPageId(pageId uint64) CheckOption {
+	return func(c *checkConfig) {
+		c.pageId = pageId
+	}
+}
+
+// KVStringer allows to prepare human-readable diagnostic messages.
+type KVStringer interface {
+	KeyToString([]byte) string
+	ValueToString([]byte) string
+}
+
+// HexKVStringer serializes both key & value to hex representation.
+func HexKVStringer() KVStringer {
+	return hexKvStringer{}
+}
+
+type hexKvStringer struct{}
+
+func (_ hexKvStringer) KeyToString(key []byte) string {
+	return hex.EncodeToString(key)
+}
+
+func (_ hexKvStringer) ValueToString(value []byte) string {
+	return hex.EncodeToString(value)
+}