diff --git a/vendor/go.etcd.io/bbolt/tx.go b/vendor/go.etcd.io/bbolt/tx.go
new file mode 100644
index 0000000..1669fb1
--- /dev/null
+++ b/vendor/go.etcd.io/bbolt/tx.go
@@ -0,0 +1,901 @@
+package bbolt
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"runtime"
+	"sort"
+	"strings"
+	"sync/atomic"
+	"time"
+	"unsafe"
+
+	berrors "go.etcd.io/bbolt/errors"
+	"go.etcd.io/bbolt/internal/common"
+)
+
+// Tx represents a read-only or read/write transaction on the database.
+// Read-only transactions can be used for retrieving values for keys and creating cursors.
+// Read/write transactions can create and remove buckets and create and remove keys.
+//
+// IMPORTANT: You must commit or rollback transactions when you are done with
+// them. Pages can not be reclaimed by the writer until no more transactions
+// are using them. A long running read transaction can cause the database to
+// quickly grow.
+type Tx struct {
+	writable       bool
+	managed        bool
+	db             *DB
+	meta           *common.Meta
+	root           Bucket
+	pages          map[common.Pgid]*common.Page
+	stats          TxStats
+	commitHandlers []func()
+
+	// WriteFlag specifies the flag for write-related methods like WriteTo().
+	// Tx opens the database file with the specified flag to copy the data.
+	//
+	// By default, the flag is unset, which works well for mostly in-memory
+	// workloads. For databases that are much larger than available RAM,
+	// set the flag to syscall.O_DIRECT to avoid trashing the page cache.
+	WriteFlag int
+}
+
+// init initializes the transaction.
+func (tx *Tx) init(db *DB) {
+	tx.db = db
+	tx.pages = nil
+
+	// Copy the meta page since it can be changed by the writer.
+	tx.meta = &common.Meta{}
+	db.meta().Copy(tx.meta)
+
+	// Copy over the root bucket.
+	tx.root = newBucket(tx)
+	tx.root.InBucket = &common.InBucket{}
+	*tx.root.InBucket = *(tx.meta.RootBucket())
+
+	// Increment the transaction id and add a page cache for writable transactions.
+	if tx.writable {
+		tx.pages = make(map[common.Pgid]*common.Page)
+		tx.meta.IncTxid()
+	}
+}
+
+// ID returns the transaction id.
+func (tx *Tx) ID() int {
+	if tx == nil || tx.meta == nil {
+		return -1
+	}
+	return int(tx.meta.Txid())
+}
+
+// DB returns a reference to the database that created the transaction.
+func (tx *Tx) DB() *DB {
+	return tx.db
+}
+
+// Size returns current database size in bytes as seen by this transaction.
+func (tx *Tx) Size() int64 {
+	return int64(tx.meta.Pgid()) * int64(tx.db.pageSize)
+}
+
+// Writable returns whether the transaction can perform write operations.
+func (tx *Tx) Writable() bool {
+	return tx.writable
+}
+
+// Cursor creates a cursor associated with the root bucket.
+// All items in the cursor will return a nil value because all root bucket keys point to buckets.
+// The cursor is only valid as long as the transaction is open.
+// Do not use a cursor after the transaction is closed.
+func (tx *Tx) Cursor() *Cursor {
+	return tx.root.Cursor()
+}
+
+// Stats retrieves a copy of the current transaction statistics.
+func (tx *Tx) Stats() TxStats {
+	return tx.stats
+}
+
+// Inspect returns the structure of the database.
+func (tx *Tx) Inspect() BucketStructure {
+	return tx.root.Inspect()
+}
+
+// Bucket retrieves a bucket by name.
+// Returns nil if the bucket does not exist.
+// The bucket instance is only valid for the lifetime of the transaction.
+func (tx *Tx) Bucket(name []byte) *Bucket {
+	return tx.root.Bucket(name)
+}
+
+// CreateBucket creates a new bucket.
+// Returns an error if the bucket already exists, if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
+func (tx *Tx) CreateBucket(name []byte) (*Bucket, error) {
+	return tx.root.CreateBucket(name)
+}
+
+// CreateBucketIfNotExists creates a new bucket if it doesn't already exist.
+// Returns an error if the bucket name is blank, or if the bucket name is too long.
+// The bucket instance is only valid for the lifetime of the transaction.
+func (tx *Tx) CreateBucketIfNotExists(name []byte) (*Bucket, error) {
+	return tx.root.CreateBucketIfNotExists(name)
+}
+
+// DeleteBucket deletes a bucket.
+// Returns an error if the bucket cannot be found or if the key represents a non-bucket value.
+func (tx *Tx) DeleteBucket(name []byte) error {
+	return tx.root.DeleteBucket(name)
+}
+
+// MoveBucket moves a sub-bucket from the source bucket to the destination bucket.
+// Returns an error if
+//  1. the sub-bucket cannot be found in the source bucket;
+//  2. or the key already exists in the destination bucket;
+//  3. the key represents a non-bucket value.
+//
+// If src is nil, it means moving a top level bucket into the target bucket.
+// If dst is nil, it means converting the child bucket into a top level bucket.
+func (tx *Tx) MoveBucket(child []byte, src *Bucket, dst *Bucket) error {
+	if src == nil {
+		src = &tx.root
+	}
+	if dst == nil {
+		dst = &tx.root
+	}
+	return src.MoveBucket(child, dst)
+}
+
+// ForEach executes a function for each bucket in the root.
+// If the provided function returns an error then the iteration is stopped and
+// the error is returned to the caller.
+func (tx *Tx) ForEach(fn func(name []byte, b *Bucket) error) error {
+	return tx.root.ForEach(func(k, v []byte) error {
+		return fn(k, tx.root.Bucket(k))
+	})
+}
+
+// OnCommit adds a handler function to be executed after the transaction successfully commits.
+func (tx *Tx) OnCommit(fn func()) {
+	tx.commitHandlers = append(tx.commitHandlers, fn)
+}
+
+// Commit writes all changes to disk, updates the meta page and closes the transaction.
+// Returns an error if a disk write error occurs, or if Commit is
+// called on a read-only transaction.
+func (tx *Tx) Commit() (err error) {
+	txId := tx.ID()
+	lg := tx.db.Logger()
+	if lg != discardLogger {
+		lg.Debugf("Committing transaction %d", txId)
+		defer func() {
+			if err != nil {
+				lg.Errorf("Committing transaction failed: %v", err)
+			} else {
+				lg.Debugf("Committing transaction %d successfully", txId)
+			}
+		}()
+	}
+
+	common.Assert(!tx.managed, "managed tx commit not allowed")
+	if tx.db == nil {
+		return berrors.ErrTxClosed
+	} else if !tx.writable {
+		return berrors.ErrTxNotWritable
+	}
+
+	// TODO(benbjohnson): Use vectorized I/O to write out dirty pages.
+
+	// Rebalance nodes which have had deletions.
+	var startTime = time.Now()
+	tx.root.rebalance()
+	if tx.stats.GetRebalance() > 0 {
+		tx.stats.IncRebalanceTime(time.Since(startTime))
+	}
+
+	opgid := tx.meta.Pgid()
+
+	// spill data onto dirty pages.
+	startTime = time.Now()
+	if err = tx.root.spill(); err != nil {
+		lg.Errorf("spilling data onto dirty pages failed: %v", err)
+		tx.rollback()
+		return err
+	}
+	tx.stats.IncSpillTime(time.Since(startTime))
+
+	// Free the old root bucket.
+	tx.meta.RootBucket().SetRootPage(tx.root.RootPage())
+
+	// Free the old freelist because commit writes out a fresh freelist.
+	if tx.meta.Freelist() != common.PgidNoFreelist {
+		tx.db.freelist.Free(tx.meta.Txid(), tx.db.page(tx.meta.Freelist()))
+	}
+
+	if !tx.db.NoFreelistSync {
+		err = tx.commitFreelist()
+		if err != nil {
+			lg.Errorf("committing freelist failed: %v", err)
+			return err
+		}
+	} else {
+		tx.meta.SetFreelist(common.PgidNoFreelist)
+	}
+
+	// If the high water mark has moved up then attempt to grow the database.
+	if tx.meta.Pgid() > opgid {
+		_ = errors.New("")
+		// gofail: var lackOfDiskSpace string
+		// tx.rollback()
+		// return errors.New(lackOfDiskSpace)
+		if err = tx.db.grow(int(tx.meta.Pgid()+1) * tx.db.pageSize); err != nil {
+			lg.Errorf("growing db size failed, pgid: %d, pagesize: %d, error: %v", tx.meta.Pgid(), tx.db.pageSize, err)
+			tx.rollback()
+			return err
+		}
+	}
+
+	// Write dirty pages to disk.
+	startTime = time.Now()
+	if err = tx.write(); err != nil {
+		lg.Errorf("writing data failed: %v", err)
+		tx.rollback()
+		return err
+	}
+
+	// If strict mode is enabled then perform a consistency check.
+	if tx.db.StrictMode {
+		ch := tx.Check()
+		var errs []string
+		for {
+			chkErr, ok := <-ch
+			if !ok {
+				break
+			}
+			errs = append(errs, chkErr.Error())
+		}
+		if len(errs) > 0 {
+			panic("check fail: " + strings.Join(errs, "\n"))
+		}
+	}
+
+	// Write meta to disk.
+	if err = tx.writeMeta(); err != nil {
+		lg.Errorf("writeMeta failed: %v", err)
+		tx.rollback()
+		return err
+	}
+	tx.stats.IncWriteTime(time.Since(startTime))
+
+	// Finalize the transaction.
+	tx.close()
+
+	// Execute commit handlers now that the locks have been removed.
+	for _, fn := range tx.commitHandlers {
+		fn()
+	}
+
+	return nil
+}
+
+func (tx *Tx) commitFreelist() error {
+	// Allocate new pages for the new free list. This will overestimate
+	// the size of the freelist but not underestimate the size (which would be bad).
+	p, err := tx.allocate((tx.db.freelist.EstimatedWritePageSize() / tx.db.pageSize) + 1)
+	if err != nil {
+		tx.rollback()
+		return err
+	}
+
+	tx.db.freelist.Write(p)
+	tx.meta.SetFreelist(p.Id())
+
+	return nil
+}
+
+// Rollback closes the transaction and ignores all previous updates. Read-only
+// transactions must be rolled back and not committed.
+func (tx *Tx) Rollback() error {
+	common.Assert(!tx.managed, "managed tx rollback not allowed")
+	if tx.db == nil {
+		return berrors.ErrTxClosed
+	}
+	tx.nonPhysicalRollback()
+	return nil
+}
+
+// nonPhysicalRollback is called when user calls Rollback directly, in this case we do not need to reload the free pages from disk.
+func (tx *Tx) nonPhysicalRollback() {
+	if tx.db == nil {
+		return
+	}
+	if tx.writable {
+		tx.db.freelist.Rollback(tx.meta.Txid())
+	}
+	tx.close()
+}
+
+// rollback needs to reload the free pages from disk in case some system error happens like fsync error.
+func (tx *Tx) rollback() {
+	if tx.db == nil {
+		return
+	}
+	if tx.writable {
+		tx.db.freelist.Rollback(tx.meta.Txid())
+		// When mmap fails, the `data`, `dataref` and `datasz` may be reset to
+		// zero values, and there is no way to reload free page IDs in this case.
+		if tx.db.data != nil {
+			if !tx.db.hasSyncedFreelist() {
+				// Reconstruct free page list by scanning the DB to get the whole free page list.
+				// Note: scanning the whole db is heavy if your db size is large in NoSyncFreeList mode.
+				tx.db.freelist.NoSyncReload(tx.db.freepages())
+			} else {
+				// Read free page list from freelist page.
+				tx.db.freelist.Reload(tx.db.page(tx.db.meta().Freelist()))
+			}
+		}
+	}
+	tx.close()
+}
+
+func (tx *Tx) close() {
+	if tx.db == nil {
+		return
+	}
+	if tx.writable {
+		// Grab freelist stats.
+		var freelistFreeN = tx.db.freelist.FreeCount()
+		var freelistPendingN = tx.db.freelist.PendingCount()
+		var freelistAlloc = tx.db.freelist.EstimatedWritePageSize()
+
+		// Remove transaction ref & writer lock.
+		tx.db.rwtx = nil
+		tx.db.rwlock.Unlock()
+
+		// Merge statistics.
+		tx.db.statlock.Lock()
+		tx.db.stats.FreePageN = freelistFreeN
+		tx.db.stats.PendingPageN = freelistPendingN
+		tx.db.stats.FreeAlloc = (freelistFreeN + freelistPendingN) * tx.db.pageSize
+		tx.db.stats.FreelistInuse = freelistAlloc
+		tx.db.stats.TxStats.add(&tx.stats)
+		tx.db.statlock.Unlock()
+	} else {
+		tx.db.removeTx(tx)
+	}
+
+	// Clear all references.
+	tx.db = nil
+	tx.meta = nil
+	tx.root = Bucket{tx: tx}
+	tx.pages = nil
+}
+
+// Copy writes the entire database to a writer.
+// This function exists for backwards compatibility.
+//
+// Deprecated: Use WriteTo() instead.
+func (tx *Tx) Copy(w io.Writer) error {
+	_, err := tx.WriteTo(w)
+	return err
+}
+
+// WriteTo writes the entire database to a writer.
+// If err == nil then exactly tx.Size() bytes will be written into the writer.
+func (tx *Tx) WriteTo(w io.Writer) (n int64, err error) {
+	var f *os.File
+	// There is a risk that between the time a read-only transaction
+	// is created and the time the file is actually opened, the
+	// underlying db file at tx.db.path may have been replaced
+	// (e.g. via rename). In that case, opening the file again would
+	// unexpectedly point to a different file, rather than the one
+	// the transaction was based on.
+	//
+	// To overcome this, we reuse the already opened file handle when
+	// WritFlag not set. When the WriteFlag is set, we reopen the file
+	// but verify that it still refers to the same underlying file
+	// (by device and inode). If it does not, we fall back to
+	// reusing the existing already opened file handle.
+	if tx.WriteFlag != 0 {
+		// Attempt to open reader with WriteFlag
+		f, err = tx.db.openFile(tx.db.path, os.O_RDONLY|tx.WriteFlag, 0)
+		if err != nil {
+			return 0, err
+		}
+
+		if ok, err := sameFile(tx.db.file, f); !ok {
+			lg := tx.db.Logger()
+			if cerr := f.Close(); cerr != nil {
+				lg.Errorf("failed to close the file (%s): %v", tx.db.path, cerr)
+			}
+			lg.Warningf("The underlying file has changed, so reuse the already opened file (%s): %v", tx.db.path, err)
+			f = tx.db.file
+		} else {
+			defer func() {
+				if cerr := f.Close(); err == nil {
+					err = cerr
+				}
+			}()
+		}
+	} else {
+		f = tx.db.file
+	}
+
+	// Generate a meta page. We use the same page data for both meta pages.
+	buf := make([]byte, tx.db.pageSize)
+	page := (*common.Page)(unsafe.Pointer(&buf[0]))
+	page.SetFlags(common.MetaPageFlag)
+	*page.Meta() = *tx.meta
+
+	// Write meta 0.
+	page.SetId(0)
+	page.Meta().SetChecksum(page.Meta().Sum64())
+	nn, err := w.Write(buf)
+	n += int64(nn)
+	if err != nil {
+		return n, fmt.Errorf("meta 0 copy: %s", err)
+	}
+
+	// Write meta 1 with a lower transaction id.
+	page.SetId(1)
+	page.Meta().DecTxid()
+	page.Meta().SetChecksum(page.Meta().Sum64())
+	nn, err = w.Write(buf)
+	n += int64(nn)
+	if err != nil {
+		return n, fmt.Errorf("meta 1 copy: %s", err)
+	}
+
+	// Copy data pages using a SectionReader to avoid affecting f's offset.
+	dataOffset := int64(tx.db.pageSize * 2)
+	dataSize := tx.Size() - dataOffset
+	sr := io.NewSectionReader(f, dataOffset, dataSize)
+
+	// Copy data pages.
+	wn, err := io.CopyN(w, sr, dataSize)
+	n += wn
+	if err != nil {
+		return n, err
+	}
+
+	return n, nil
+}
+
+func sameFile(f1, f2 *os.File) (bool, error) {
+	fi1, err := f1.Stat()
+	if err != nil {
+		return false, fmt.Errorf("failed to get fileInfo of the first file (%s): %w", f1.Name(), err)
+	}
+	fi2, err := f2.Stat()
+	if err != nil {
+		return false, fmt.Errorf("failed to get fileInfo of the second file (%s): %w", f2.Name(), err)
+	}
+
+	return os.SameFile(fi1, fi2), nil
+}
+
+// CopyFile copies the entire database to file at the given path.
+// A reader transaction is maintained during the copy so it is safe to continue
+// using the database while a copy is in progress.
+func (tx *Tx) CopyFile(path string, mode os.FileMode) error {
+	f, err := tx.db.openFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode)
+	if err != nil {
+		return err
+	}
+
+	_, err = tx.WriteTo(f)
+	if err != nil {
+		_ = f.Close()
+		return err
+	}
+	return f.Close()
+}
+
+// allocate returns a contiguous block of memory starting at a given page.
+func (tx *Tx) allocate(count int) (*common.Page, error) {
+	lg := tx.db.Logger()
+	p, err := tx.db.allocate(tx.meta.Txid(), count)
+	if err != nil {
+		lg.Errorf("allocating failed, txid: %d, count: %d, error: %v", tx.meta.Txid(), count, err)
+		return nil, err
+	}
+
+	// Save to our page cache.
+	tx.pages[p.Id()] = p
+
+	// Update statistics.
+	tx.stats.IncPageCount(int64(count))
+	tx.stats.IncPageAlloc(int64(count * tx.db.pageSize))
+
+	return p, nil
+}
+
+// write writes any dirty pages to disk.
+func (tx *Tx) write() error {
+	// Sort pages by id.
+	lg := tx.db.Logger()
+	pages := make(common.Pages, 0, len(tx.pages))
+	for _, p := range tx.pages {
+		pages = append(pages, p)
+	}
+	// Clear out page cache early.
+	tx.pages = make(map[common.Pgid]*common.Page)
+	sort.Sort(pages)
+
+	// Write pages to disk in order.
+	for _, p := range pages {
+		rem := (uint64(p.Overflow()) + 1) * uint64(tx.db.pageSize)
+		offset := int64(p.Id()) * int64(tx.db.pageSize)
+		var written uintptr
+
+		// Write out page in "max allocation" sized chunks.
+		for {
+			sz := rem
+			if sz > common.MaxAllocSize-1 {
+				sz = common.MaxAllocSize - 1
+			}
+			buf := common.UnsafeByteSlice(unsafe.Pointer(p), written, 0, int(sz))
+
+			if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
+				lg.Errorf("writeAt failed, offset: %d: %w", offset, err)
+				return err
+			}
+
+			// Update statistics.
+			tx.stats.IncWrite(1)
+
+			// Exit inner for loop if we've written all the chunks.
+			rem -= sz
+			if rem == 0 {
+				break
+			}
+
+			// Otherwise move offset forward and move pointer to next chunk.
+			offset += int64(sz)
+			written += uintptr(sz)
+		}
+	}
+
+	// Ignore file sync if flag is set on DB.
+	if !tx.db.NoSync || common.IgnoreNoSync {
+		// gofail: var beforeSyncDataPages struct{}
+		if err := fdatasync(tx.db); err != nil {
+			lg.Errorf("[GOOS: %s, GOARCH: %s] fdatasync failed: %w", runtime.GOOS, runtime.GOARCH, err)
+			return err
+		}
+	}
+
+	// Put small pages back to page pool.
+	for _, p := range pages {
+		// Ignore page sizes over 1 page.
+		// These are allocated using make() instead of the page pool.
+		if int(p.Overflow()) != 0 {
+			continue
+		}
+
+		buf := common.UnsafeByteSlice(unsafe.Pointer(p), 0, 0, tx.db.pageSize)
+
+		// See https://go.googlesource.com/go/+/f03c9202c43e0abb130669852082117ca50aa9b1
+		for i := range buf {
+			buf[i] = 0
+		}
+		tx.db.pagePool.Put(buf) //nolint:staticcheck
+	}
+
+	return nil
+}
+
+// writeMeta writes the meta to the disk.
+func (tx *Tx) writeMeta() error {
+	// gofail: var beforeWriteMetaError string
+	// return errors.New(beforeWriteMetaError)
+
+	// Create a temporary buffer for the meta page.
+	lg := tx.db.Logger()
+	buf := make([]byte, tx.db.pageSize)
+	p := tx.db.pageInBuffer(buf, 0)
+	tx.meta.Write(p)
+
+	// Write the meta page to file.
+	tx.db.metalock.Lock()
+	if _, err := tx.db.ops.writeAt(buf, int64(p.Id())*int64(tx.db.pageSize)); err != nil {
+		tx.db.metalock.Unlock()
+		lg.Errorf("writeAt failed, pgid: %d, pageSize: %d, error: %v", p.Id(), tx.db.pageSize, err)
+		return err
+	}
+	tx.db.metalock.Unlock()
+	if !tx.db.NoSync || common.IgnoreNoSync {
+		// gofail: var beforeSyncMetaPage struct{}
+		if err := fdatasync(tx.db); err != nil {
+			lg.Errorf("[GOOS: %s, GOARCH: %s] fdatasync failed: %w", runtime.GOOS, runtime.GOARCH, err)
+			return err
+		}
+	}
+
+	// Update statistics.
+	tx.stats.IncWrite(1)
+
+	return nil
+}
+
+// page returns a reference to the page with a given id.
+// If page has been written to then a temporary buffered page is returned.
+func (tx *Tx) page(id common.Pgid) *common.Page {
+	// Check the dirty pages first.
+	if tx.pages != nil {
+		if p, ok := tx.pages[id]; ok {
+			p.FastCheck(id)
+			return p
+		}
+	}
+
+	// Otherwise return directly from the mmap.
+	p := tx.db.page(id)
+	p.FastCheck(id)
+	return p
+}
+
+// forEachPage iterates over every page within a given page and executes a function.
+func (tx *Tx) forEachPage(pgidnum common.Pgid, fn func(*common.Page, int, []common.Pgid)) {
+	stack := make([]common.Pgid, 10)
+	stack[0] = pgidnum
+	tx.forEachPageInternal(stack[:1], fn)
+}
+
+func (tx *Tx) forEachPageInternal(pgidstack []common.Pgid, fn func(*common.Page, int, []common.Pgid)) {
+	p := tx.page(pgidstack[len(pgidstack)-1])
+
+	// Execute function.
+	fn(p, len(pgidstack)-1, pgidstack)
+
+	// Recursively loop over children.
+	if p.IsBranchPage() {
+		for i := 0; i < int(p.Count()); i++ {
+			elem := p.BranchPageElement(uint16(i))
+			tx.forEachPageInternal(append(pgidstack, elem.Pgid()), fn)
+		}
+	}
+}
+
+// Page returns page information for a given page number.
+// This is only safe for concurrent use when used by a writable transaction.
+func (tx *Tx) Page(id int) (*common.PageInfo, error) {
+	if tx.db == nil {
+		return nil, berrors.ErrTxClosed
+	} else if common.Pgid(id) >= tx.meta.Pgid() {
+		return nil, nil
+	}
+
+	if tx.db.freelist == nil {
+		return nil, berrors.ErrFreePagesNotLoaded
+	}
+
+	// Build the page info.
+	p := tx.db.page(common.Pgid(id))
+	info := &common.PageInfo{
+		ID:            id,
+		Count:         int(p.Count()),
+		OverflowCount: int(p.Overflow()),
+	}
+
+	// Determine the type (or if it's free).
+	if tx.db.freelist.Freed(common.Pgid(id)) {
+		info.Type = "free"
+	} else {
+		info.Type = p.Typ()
+	}
+
+	return info, nil
+}
+
+// TxStats represents statistics about the actions performed by the transaction.
+type TxStats struct {
+	// Page statistics.
+	//
+	// DEPRECATED: Use GetPageCount() or IncPageCount()
+	PageCount int64 // number of page allocations
+	// DEPRECATED: Use GetPageAlloc() or IncPageAlloc()
+	PageAlloc int64 // total bytes allocated
+
+	// Cursor statistics.
+	//
+	// DEPRECATED: Use GetCursorCount() or IncCursorCount()
+	CursorCount int64 // number of cursors created
+
+	// Node statistics
+	//
+	// DEPRECATED: Use GetNodeCount() or IncNodeCount()
+	NodeCount int64 // number of node allocations
+	// DEPRECATED: Use GetNodeDeref() or IncNodeDeref()
+	NodeDeref int64 // number of node dereferences
+
+	// Rebalance statistics.
+	//
+	// DEPRECATED: Use GetRebalance() or IncRebalance()
+	Rebalance int64 // number of node rebalances
+	// DEPRECATED: Use GetRebalanceTime() or IncRebalanceTime()
+	RebalanceTime time.Duration // total time spent rebalancing
+
+	// Split/Spill statistics.
+	//
+	// DEPRECATED: Use GetSplit() or IncSplit()
+	Split int64 // number of nodes split
+	// DEPRECATED: Use GetSpill() or IncSpill()
+	Spill int64 // number of nodes spilled
+	// DEPRECATED: Use GetSpillTime() or IncSpillTime()
+	SpillTime time.Duration // total time spent spilling
+
+	// Write statistics.
+	//
+	// DEPRECATED: Use GetWrite() or IncWrite()
+	Write int64 // number of writes performed
+	// DEPRECATED: Use GetWriteTime() or IncWriteTime()
+	WriteTime time.Duration // total time spent writing to disk
+}
+
+func (s *TxStats) add(other *TxStats) {
+	s.IncPageCount(other.GetPageCount())
+	s.IncPageAlloc(other.GetPageAlloc())
+	s.IncCursorCount(other.GetCursorCount())
+	s.IncNodeCount(other.GetNodeCount())
+	s.IncNodeDeref(other.GetNodeDeref())
+	s.IncRebalance(other.GetRebalance())
+	s.IncRebalanceTime(other.GetRebalanceTime())
+	s.IncSplit(other.GetSplit())
+	s.IncSpill(other.GetSpill())
+	s.IncSpillTime(other.GetSpillTime())
+	s.IncWrite(other.GetWrite())
+	s.IncWriteTime(other.GetWriteTime())
+}
+
+// Sub calculates and returns the difference between two sets of transaction stats.
+// This is useful when obtaining stats at two different points and time and
+// you need the performance counters that occurred within that time span.
+func (s *TxStats) Sub(other *TxStats) TxStats {
+	var diff TxStats
+	diff.PageCount = s.GetPageCount() - other.GetPageCount()
+	diff.PageAlloc = s.GetPageAlloc() - other.GetPageAlloc()
+	diff.CursorCount = s.GetCursorCount() - other.GetCursorCount()
+	diff.NodeCount = s.GetNodeCount() - other.GetNodeCount()
+	diff.NodeDeref = s.GetNodeDeref() - other.GetNodeDeref()
+	diff.Rebalance = s.GetRebalance() - other.GetRebalance()
+	diff.RebalanceTime = s.GetRebalanceTime() - other.GetRebalanceTime()
+	diff.Split = s.GetSplit() - other.GetSplit()
+	diff.Spill = s.GetSpill() - other.GetSpill()
+	diff.SpillTime = s.GetSpillTime() - other.GetSpillTime()
+	diff.Write = s.GetWrite() - other.GetWrite()
+	diff.WriteTime = s.GetWriteTime() - other.GetWriteTime()
+	return diff
+}
+
+// GetPageCount returns PageCount atomically.
+func (s *TxStats) GetPageCount() int64 {
+	return atomic.LoadInt64(&s.PageCount)
+}
+
+// IncPageCount increases PageCount atomically and returns the new value.
+func (s *TxStats) IncPageCount(delta int64) int64 {
+	return atomic.AddInt64(&s.PageCount, delta)
+}
+
+// GetPageAlloc returns PageAlloc atomically.
+func (s *TxStats) GetPageAlloc() int64 {
+	return atomic.LoadInt64(&s.PageAlloc)
+}
+
+// IncPageAlloc increases PageAlloc atomically and returns the new value.
+func (s *TxStats) IncPageAlloc(delta int64) int64 {
+	return atomic.AddInt64(&s.PageAlloc, delta)
+}
+
+// GetCursorCount returns CursorCount atomically.
+func (s *TxStats) GetCursorCount() int64 {
+	return atomic.LoadInt64(&s.CursorCount)
+}
+
+// IncCursorCount increases CursorCount atomically and return the new value.
+func (s *TxStats) IncCursorCount(delta int64) int64 {
+	return atomic.AddInt64(&s.CursorCount, delta)
+}
+
+// GetNodeCount returns NodeCount atomically.
+func (s *TxStats) GetNodeCount() int64 {
+	return atomic.LoadInt64(&s.NodeCount)
+}
+
+// IncNodeCount increases NodeCount atomically and returns the new value.
+func (s *TxStats) IncNodeCount(delta int64) int64 {
+	return atomic.AddInt64(&s.NodeCount, delta)
+}
+
+// GetNodeDeref returns NodeDeref atomically.
+func (s *TxStats) GetNodeDeref() int64 {
+	return atomic.LoadInt64(&s.NodeDeref)
+}
+
+// IncNodeDeref increases NodeDeref atomically and returns the new value.
+func (s *TxStats) IncNodeDeref(delta int64) int64 {
+	return atomic.AddInt64(&s.NodeDeref, delta)
+}
+
+// GetRebalance returns Rebalance atomically.
+func (s *TxStats) GetRebalance() int64 {
+	return atomic.LoadInt64(&s.Rebalance)
+}
+
+// IncRebalance increases Rebalance atomically and returns the new value.
+func (s *TxStats) IncRebalance(delta int64) int64 {
+	return atomic.AddInt64(&s.Rebalance, delta)
+}
+
+// GetRebalanceTime returns RebalanceTime atomically.
+func (s *TxStats) GetRebalanceTime() time.Duration {
+	return atomicLoadDuration(&s.RebalanceTime)
+}
+
+// IncRebalanceTime increases RebalanceTime atomically and returns the new value.
+func (s *TxStats) IncRebalanceTime(delta time.Duration) time.Duration {
+	return atomicAddDuration(&s.RebalanceTime, delta)
+}
+
+// GetSplit returns Split atomically.
+func (s *TxStats) GetSplit() int64 {
+	return atomic.LoadInt64(&s.Split)
+}
+
+// IncSplit increases Split atomically and returns the new value.
+func (s *TxStats) IncSplit(delta int64) int64 {
+	return atomic.AddInt64(&s.Split, delta)
+}
+
+// GetSpill returns Spill atomically.
+func (s *TxStats) GetSpill() int64 {
+	return atomic.LoadInt64(&s.Spill)
+}
+
+// IncSpill increases Spill atomically and returns the new value.
+func (s *TxStats) IncSpill(delta int64) int64 {
+	return atomic.AddInt64(&s.Spill, delta)
+}
+
+// GetSpillTime returns SpillTime atomically.
+func (s *TxStats) GetSpillTime() time.Duration {
+	return atomicLoadDuration(&s.SpillTime)
+}
+
+// IncSpillTime increases SpillTime atomically and returns the new value.
+func (s *TxStats) IncSpillTime(delta time.Duration) time.Duration {
+	return atomicAddDuration(&s.SpillTime, delta)
+}
+
+// GetWrite returns Write atomically.
+func (s *TxStats) GetWrite() int64 {
+	return atomic.LoadInt64(&s.Write)
+}
+
+// IncWrite increases Write atomically and returns the new value.
+func (s *TxStats) IncWrite(delta int64) int64 {
+	return atomic.AddInt64(&s.Write, delta)
+}
+
+// GetWriteTime returns WriteTime atomically.
+func (s *TxStats) GetWriteTime() time.Duration {
+	return atomicLoadDuration(&s.WriteTime)
+}
+
+// IncWriteTime increases WriteTime atomically and returns the new value.
+func (s *TxStats) IncWriteTime(delta time.Duration) time.Duration {
+	return atomicAddDuration(&s.WriteTime, delta)
+}
+
+func atomicAddDuration(ptr *time.Duration, du time.Duration) time.Duration {
+	return time.Duration(atomic.AddInt64((*int64)(unsafe.Pointer(ptr)), int64(du)))
+}
+
+func atomicLoadDuration(ptr *time.Duration) time.Duration {
+	return time.Duration(atomic.LoadInt64((*int64)(unsafe.Pointer(ptr))))
+}