diff --git a/vendor/go.etcd.io/bbolt/node.go b/vendor/go.etcd.io/bbolt/node.go
new file mode 100644
index 0000000..022b100
--- /dev/null
+++ b/vendor/go.etcd.io/bbolt/node.go
@@ -0,0 +1,538 @@
+package bbolt
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+
+	"go.etcd.io/bbolt/internal/common"
+)
+
+// node represents an in-memory, deserialized page.
+type node struct {
+	bucket     *Bucket
+	isLeaf     bool
+	unbalanced bool
+	spilled    bool
+	key        []byte
+	pgid       common.Pgid
+	parent     *node
+	children   nodes
+	inodes     common.Inodes
+}
+
+// root returns the top-level node this node is attached to.
+func (n *node) root() *node {
+	if n.parent == nil {
+		return n
+	}
+	return n.parent.root()
+}
+
+// minKeys returns the minimum number of inodes this node should have.
+func (n *node) minKeys() int {
+	if n.isLeaf {
+		return 1
+	}
+	return 2
+}
+
+// size returns the size of the node after serialization.
+func (n *node) size() int {
+	sz, elsz := common.PageHeaderSize, n.pageElementSize()
+	for i := 0; i < len(n.inodes); i++ {
+		item := &n.inodes[i]
+		sz += elsz + uintptr(len(item.Key())) + uintptr(len(item.Value()))
+	}
+	return int(sz)
+}
+
+// sizeLessThan returns true if the node is less than a given size.
+// This is an optimization to avoid calculating a large node when we only need
+// to know if it fits inside a certain page size.
+func (n *node) sizeLessThan(v uintptr) bool {
+	sz, elsz := common.PageHeaderSize, n.pageElementSize()
+	for i := 0; i < len(n.inodes); i++ {
+		item := &n.inodes[i]
+		sz += elsz + uintptr(len(item.Key())) + uintptr(len(item.Value()))
+		if sz >= v {
+			return false
+		}
+	}
+	return true
+}
+
+// pageElementSize returns the size of each page element based on the type of node.
+func (n *node) pageElementSize() uintptr {
+	if n.isLeaf {
+		return common.LeafPageElementSize
+	}
+	return common.BranchPageElementSize
+}
+
+// childAt returns the child node at a given index.
+func (n *node) childAt(index int) *node {
+	if n.isLeaf {
+		panic(fmt.Sprintf("invalid childAt(%d) on a leaf node", index))
+	}
+	return n.bucket.node(n.inodes[index].Pgid(), n)
+}
+
+// childIndex returns the index of a given child node.
+func (n *node) childIndex(child *node) int {
+	index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].Key(), child.key) != -1 })
+	return index
+}
+
+// numChildren returns the number of children.
+func (n *node) numChildren() int {
+	return len(n.inodes)
+}
+
+// nextSibling returns the next node with the same parent.
+func (n *node) nextSibling() *node {
+	if n.parent == nil {
+		return nil
+	}
+	index := n.parent.childIndex(n)
+	if index >= n.parent.numChildren()-1 {
+		return nil
+	}
+	return n.parent.childAt(index + 1)
+}
+
+// prevSibling returns the previous node with the same parent.
+func (n *node) prevSibling() *node {
+	if n.parent == nil {
+		return nil
+	}
+	index := n.parent.childIndex(n)
+	if index == 0 {
+		return nil
+	}
+	return n.parent.childAt(index - 1)
+}
+
+// put inserts a key/value.
+func (n *node) put(oldKey, newKey, value []byte, pgId common.Pgid, flags uint32) {
+	if pgId >= n.bucket.tx.meta.Pgid() {
+		panic(fmt.Sprintf("pgId (%d) above high water mark (%d)", pgId, n.bucket.tx.meta.Pgid()))
+	} else if len(oldKey) <= 0 {
+		panic("put: zero-length old key")
+	} else if len(newKey) <= 0 {
+		panic("put: zero-length new key")
+	}
+
+	// Find insertion index.
+	index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].Key(), oldKey) != -1 })
+
+	// Add capacity and shift nodes if we don't have an exact match and need to insert.
+	exact := len(n.inodes) > 0 && index < len(n.inodes) && bytes.Equal(n.inodes[index].Key(), oldKey)
+	if !exact {
+		n.inodes = append(n.inodes, common.Inode{})
+		copy(n.inodes[index+1:], n.inodes[index:])
+	}
+
+	inode := &n.inodes[index]
+	inode.SetFlags(flags)
+	inode.SetKey(newKey)
+	inode.SetValue(value)
+	inode.SetPgid(pgId)
+	common.Assert(len(inode.Key()) > 0, "put: zero-length inode key")
+}
+
+// del removes a key from the node.
+func (n *node) del(key []byte) {
+	// Find index of key.
+	index := sort.Search(len(n.inodes), func(i int) bool { return bytes.Compare(n.inodes[i].Key(), key) != -1 })
+
+	// Exit if the key isn't found.
+	if index >= len(n.inodes) || !bytes.Equal(n.inodes[index].Key(), key) {
+		return
+	}
+
+	// Delete inode from the node.
+	n.inodes = append(n.inodes[:index], n.inodes[index+1:]...)
+
+	// Mark the node as needing rebalancing.
+	n.unbalanced = true
+}
+
+// read initializes the node from a page.
+func (n *node) read(p *common.Page) {
+	n.pgid = p.Id()
+	n.isLeaf = p.IsLeafPage()
+	n.inodes = common.ReadInodeFromPage(p)
+
+	// Save first key, so we can find the node in the parent when we spill.
+	if len(n.inodes) > 0 {
+		n.key = n.inodes[0].Key()
+		common.Assert(len(n.key) > 0, "read: zero-length node key")
+	} else {
+		n.key = nil
+	}
+}
+
+// write writes the items onto one or more pages.
+// The page should have p.id (might be 0 for meta or bucket-inline page) and p.overflow set
+// and the rest should be zeroed.
+func (n *node) write(p *common.Page) {
+	common.Assert(p.Count() == 0 && p.Flags() == 0, "node cannot be written into a not empty page")
+
+	// Initialize page.
+	if n.isLeaf {
+		p.SetFlags(common.LeafPageFlag)
+	} else {
+		p.SetFlags(common.BranchPageFlag)
+	}
+
+	if len(n.inodes) >= 0xFFFF {
+		panic(fmt.Sprintf("inode overflow: %d (pgid=%d)", len(n.inodes), p.Id()))
+	}
+	p.SetCount(uint16(len(n.inodes)))
+
+	// Stop here if there are no items to write.
+	if p.Count() == 0 {
+		return
+	}
+
+	common.WriteInodeToPage(n.inodes, p)
+
+	// DEBUG ONLY: n.dump()
+}
+
+// split breaks up a node into multiple smaller nodes, if appropriate.
+// This should only be called from the spill() function.
+func (n *node) split(pageSize uintptr) []*node {
+	var nodes []*node
+
+	node := n
+	for {
+		// Split node into two.
+		a, b := node.splitTwo(pageSize)
+		nodes = append(nodes, a)
+
+		// If we can't split then exit the loop.
+		if b == nil {
+			break
+		}
+
+		// Set node to b so it gets split on the next iteration.
+		node = b
+	}
+
+	return nodes
+}
+
+// splitTwo breaks up a node into two smaller nodes, if appropriate.
+// This should only be called from the split() function.
+func (n *node) splitTwo(pageSize uintptr) (*node, *node) {
+	// Ignore the split if the page doesn't have at least enough nodes for
+	// two pages or if the nodes can fit in a single page.
+	if len(n.inodes) <= (common.MinKeysPerPage*2) || n.sizeLessThan(pageSize) {
+		return n, nil
+	}
+
+	// Determine the threshold before starting a new node.
+	var fillPercent = n.bucket.FillPercent
+	if fillPercent < minFillPercent {
+		fillPercent = minFillPercent
+	} else if fillPercent > maxFillPercent {
+		fillPercent = maxFillPercent
+	}
+	threshold := int(float64(pageSize) * fillPercent)
+
+	// Determine split position and sizes of the two pages.
+	splitIndex, _ := n.splitIndex(threshold)
+
+	// Split node into two separate nodes.
+	// If there's no parent then we'll need to create one.
+	if n.parent == nil {
+		n.parent = &node{bucket: n.bucket, children: []*node{n}}
+	}
+
+	// Create a new node and add it to the parent.
+	next := &node{bucket: n.bucket, isLeaf: n.isLeaf, parent: n.parent}
+	n.parent.children = append(n.parent.children, next)
+
+	// Split inodes across two nodes.
+	next.inodes = n.inodes[splitIndex:]
+	n.inodes = n.inodes[:splitIndex]
+
+	// Update the statistics.
+	n.bucket.tx.stats.IncSplit(1)
+
+	return n, next
+}
+
+// splitIndex finds the position where a page will fill a given threshold.
+// It returns the index as well as the size of the first page.
+// This is only be called from split().
+func (n *node) splitIndex(threshold int) (index, sz uintptr) {
+	sz = common.PageHeaderSize
+
+	// Loop until we only have the minimum number of keys required for the second page.
+	for i := 0; i < len(n.inodes)-common.MinKeysPerPage; i++ {
+		index = uintptr(i)
+		inode := n.inodes[i]
+		elsize := n.pageElementSize() + uintptr(len(inode.Key())) + uintptr(len(inode.Value()))
+
+		// If we have at least the minimum number of keys and adding another
+		// node would put us over the threshold then exit and return.
+		if index >= common.MinKeysPerPage && sz+elsize > uintptr(threshold) {
+			break
+		}
+
+		// Add the element size to the total size.
+		sz += elsize
+	}
+
+	return
+}
+
+// spill writes the nodes to dirty pages and splits nodes as it goes.
+// Returns an error if dirty pages cannot be allocated.
+func (n *node) spill() error {
+	var tx = n.bucket.tx
+	if n.spilled {
+		return nil
+	}
+
+	// Spill child nodes first. Child nodes can materialize sibling nodes in
+	// the case of split-merge so we cannot use a range loop. We have to check
+	// the children size on every loop iteration.
+	sort.Sort(n.children)
+	for i := 0; i < len(n.children); i++ {
+		if err := n.children[i].spill(); err != nil {
+			return err
+		}
+	}
+
+	// We no longer need the child list because it's only used for spill tracking.
+	n.children = nil
+
+	// Split nodes into appropriate sizes. The first node will always be n.
+	var nodes = n.split(uintptr(tx.db.pageSize))
+	for _, node := range nodes {
+		// Add node's page to the freelist if it's not new.
+		if node.pgid > 0 {
+			tx.db.freelist.Free(tx.meta.Txid(), tx.page(node.pgid))
+			node.pgid = 0
+		}
+
+		// Allocate contiguous space for the node.
+		p, err := tx.allocate((node.size() + tx.db.pageSize - 1) / tx.db.pageSize)
+		if err != nil {
+			return err
+		}
+
+		// Write the node.
+		if p.Id() >= tx.meta.Pgid() {
+			panic(fmt.Sprintf("pgid (%d) above high water mark (%d)", p.Id(), tx.meta.Pgid()))
+		}
+		node.pgid = p.Id()
+		node.write(p)
+		node.spilled = true
+
+		// Insert into parent inodes.
+		if node.parent != nil {
+			var key = node.key
+			if key == nil {
+				key = node.inodes[0].Key()
+			}
+
+			node.parent.put(key, node.inodes[0].Key(), nil, node.pgid, 0)
+			node.key = node.inodes[0].Key()
+			common.Assert(len(node.key) > 0, "spill: zero-length node key")
+		}
+
+		// Update the statistics.
+		tx.stats.IncSpill(1)
+	}
+
+	// If the root node split and created a new root then we need to spill that
+	// as well. We'll clear out the children to make sure it doesn't try to respill.
+	if n.parent != nil && n.parent.pgid == 0 {
+		n.children = nil
+		return n.parent.spill()
+	}
+
+	return nil
+}
+
+// rebalance attempts to combine the node with sibling nodes if the node fill
+// size is below a threshold or if there are not enough keys.
+func (n *node) rebalance() {
+	if !n.unbalanced {
+		return
+	}
+	n.unbalanced = false
+
+	// Update statistics.
+	n.bucket.tx.stats.IncRebalance(1)
+
+	// Ignore if node is above threshold (25% when FillPercent is set to DefaultFillPercent) and has enough keys.
+	var threshold = int(float64(n.bucket.tx.db.pageSize)*n.bucket.FillPercent) / 2
+	if n.size() > threshold && len(n.inodes) > n.minKeys() {
+		return
+	}
+
+	// Root node has special handling.
+	if n.parent == nil {
+		// If root node is a branch and only has one node then collapse it.
+		if !n.isLeaf && len(n.inodes) == 1 {
+			// Move root's child up.
+			child := n.bucket.node(n.inodes[0].Pgid(), n)
+			n.isLeaf = child.isLeaf
+			n.inodes = child.inodes[:]
+			n.children = child.children
+
+			// Reparent all child nodes being moved.
+			for _, inode := range n.inodes {
+				if child, ok := n.bucket.nodes[inode.Pgid()]; ok {
+					child.parent = n
+				}
+			}
+
+			// Remove old child.
+			child.parent = nil
+			delete(n.bucket.nodes, child.pgid)
+			child.free()
+		}
+
+		return
+	}
+
+	// If node has no keys then just remove it.
+	if n.numChildren() == 0 {
+		n.parent.del(n.key)
+		n.parent.removeChild(n)
+		delete(n.bucket.nodes, n.pgid)
+		n.free()
+		n.parent.rebalance()
+		return
+	}
+
+	common.Assert(n.parent.numChildren() > 1, "parent must have at least 2 children")
+
+	// Merge with right sibling if idx == 0, otherwise left sibling.
+	var leftNode, rightNode *node
+	var useNextSibling = n.parent.childIndex(n) == 0
+	if useNextSibling {
+		leftNode = n
+		rightNode = n.nextSibling()
+	} else {
+		leftNode = n.prevSibling()
+		rightNode = n
+	}
+
+	// If both nodes are too small then merge them.
+	// Reparent all child nodes being moved.
+	for _, inode := range rightNode.inodes {
+		if child, ok := n.bucket.nodes[inode.Pgid()]; ok {
+			child.parent.removeChild(child)
+			child.parent = leftNode
+			child.parent.children = append(child.parent.children, child)
+		}
+	}
+
+	// Copy over inodes from right node to left node and remove right node.
+	leftNode.inodes = append(leftNode.inodes, rightNode.inodes...)
+	n.parent.del(rightNode.key)
+	n.parent.removeChild(rightNode)
+	delete(n.bucket.nodes, rightNode.pgid)
+	rightNode.free()
+
+	// Either this node or the sibling node was deleted from the parent so rebalance it.
+	n.parent.rebalance()
+}
+
+// removes a node from the list of in-memory children.
+// This does not affect the inodes.
+func (n *node) removeChild(target *node) {
+	for i, child := range n.children {
+		if child == target {
+			n.children = append(n.children[:i], n.children[i+1:]...)
+			return
+		}
+	}
+}
+
+// dereference causes the node to copy all its inode key/value references to heap memory.
+// This is required when the mmap is reallocated so inodes are not pointing to stale data.
+func (n *node) dereference() {
+	if n.key != nil {
+		key := make([]byte, len(n.key))
+		copy(key, n.key)
+		n.key = key
+		common.Assert(n.pgid == 0 || len(n.key) > 0, "dereference: zero-length node key on existing node")
+	}
+
+	for i := range n.inodes {
+		inode := &n.inodes[i]
+
+		key := make([]byte, len(inode.Key()))
+		copy(key, inode.Key())
+		inode.SetKey(key)
+		common.Assert(len(inode.Key()) > 0, "dereference: zero-length inode key")
+
+		value := make([]byte, len(inode.Value()))
+		copy(value, inode.Value())
+		inode.SetValue(value)
+	}
+
+	// Recursively dereference children.
+	for _, child := range n.children {
+		child.dereference()
+	}
+
+	// Update statistics.
+	n.bucket.tx.stats.IncNodeDeref(1)
+}
+
+// free adds the node's underlying page to the freelist.
+func (n *node) free() {
+	if n.pgid != 0 {
+		n.bucket.tx.db.freelist.Free(n.bucket.tx.meta.Txid(), n.bucket.tx.page(n.pgid))
+		n.pgid = 0
+	}
+}
+
+// dump writes the contents of the node to STDERR for debugging purposes.
+/*
+func (n *node) dump() {
+	// Write node header.
+	var typ = "branch"
+	if n.isLeaf {
+		typ = "leaf"
+	}
+	warnf("[NODE %d {type=%s count=%d}]", n.pgid, typ, len(n.inodes))
+
+	// Write out abbreviated version of each item.
+	for _, item := range n.inodes {
+		if n.isLeaf {
+			if item.flags&bucketLeafFlag != 0 {
+				bucket := (*bucket)(unsafe.Pointer(&item.value[0]))
+				warnf("+L %08x -> (bucket root=%d)", trunc(item.key, 4), bucket.root)
+			} else {
+				warnf("+L %08x -> %08x", trunc(item.key, 4), trunc(item.value, 4))
+			}
+		} else {
+			warnf("+B %08x -> pgid=%d", trunc(item.key, 4), item.pgid)
+		}
+	}
+	warn("")
+}
+*/
+
+func compareKeys(left, right []byte) int {
+	return bytes.Compare(left, right)
+}
+
+type nodes []*node
+
+func (s nodes) Len() int      { return len(s) }
+func (s nodes) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
+func (s nodes) Less(i, j int) bool {
+	return bytes.Compare(s[i].inodes[0].Key(), s[j].inodes[0].Key()) == -1
+}