Update vendor of boltdb and containers/image

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

1 files changed, 0 insertions, 1174 deletions

diff --git a/vendor/github.com/etcd-io/bbolt/db.go b/vendor/github.com/etcd-io/bbolt/db.go
deleted file mode 100644
index 870c8b1cc..000000000
--- a/vendor/github.com/etcd-io/bbolt/db.go
+++ /dev/null
@@ -1,1174 +0,0 @@
-package bbolt
-
-import (
-	"errors"
-	"fmt"
-	"hash/fnv"
-	"log"
-	"os"
-	"runtime"
-	"sort"
-	"sync"
-	"time"
-	"unsafe"
-)
-
-// The largest step that can be taken when remapping the mmap.
-const maxMmapStep = 1 << 30 // 1GB
-
-// The data file format version.
-const version = 2
-
-// Represents a marker value to indicate that a file is a Bolt DB.
-const magic uint32 = 0xED0CDAED
-
-const pgidNoFreelist pgid = 0xffffffffffffffff
-
-// IgnoreNoSync specifies whether the NoSync field of a DB is ignored when
-// syncing changes to a file.  This is required as some operating systems,
-// such as OpenBSD, do not have a unified buffer cache (UBC) and writes
-// must be synchronized using the msync(2) syscall.
-const IgnoreNoSync = runtime.GOOS == "openbsd"
-
-// Default values if not set in a DB instance.
-const (
-	DefaultMaxBatchSize  int = 1000
-	DefaultMaxBatchDelay     = 10 * time.Millisecond
-	DefaultAllocSize         = 16 * 1024 * 1024
-)
-
-// default page size for db is set to the OS page size.
-var defaultPageSize = os.Getpagesize()
-
-// The time elapsed between consecutive file locking attempts.
-const flockRetryTimeout = 50 * time.Millisecond
-
-// FreelistType is the type of the freelist backend
-type FreelistType string
-
-const (
-	// FreelistArrayType indicates backend freelist type is array
-	FreelistArrayType = FreelistType("array")
-	// FreelistMapType indicates backend freelist type is hashmap
-	FreelistMapType = FreelistType("hashmap")
-)
-
-// DB represents a collection of buckets persisted to a file on disk.
-// All data access is performed through transactions which can be obtained through the DB.
-// All the functions on DB will return a ErrDatabaseNotOpen if accessed before Open() is called.
-type DB struct {
-	// When enabled, the database will perform a Check() after every commit.
-	// A panic is issued if the database is in an inconsistent state. This
-	// flag has a large performance impact so it should only be used for
-	// debugging purposes.
-	StrictMode bool
-
-	// Setting the NoSync flag will cause the database to skip fsync()
-	// calls after each commit. This can be useful when bulk loading data
-	// into a database and you can restart the bulk load in the event of
-	// a system failure or database corruption. Do not set this flag for
-	// normal use.
-	//
-	// If the package global IgnoreNoSync constant is true, this value is
-	// ignored.  See the comment on that constant for more details.
-	//
-	// THIS IS UNSAFE. PLEASE USE WITH CAUTION.
-	NoSync bool
-
-	// When true, skips syncing freelist to disk. This improves the database
-	// write performance under normal operation, but requires a full database
-	// re-sync during recovery.
-	NoFreelistSync bool
-
-	// FreelistType sets the backend freelist type. There are two options. Array which is simple but endures
-	// dramatic performance degradation if database is large and framentation in freelist is common.
-	// The alternative one is using hashmap, it is faster in almost all circumstances
-	// but it doesn't guarantee that it offers the smallest page id available. In normal case it is safe.
-	// The default type is array
-	FreelistType FreelistType
-
-	// When true, skips the truncate call when growing the database.
-	// Setting this to true is only safe on non-ext3/ext4 systems.
-	// Skipping truncation avoids preallocation of hard drive space and
-	// bypasses a truncate() and fsync() syscall on remapping.
-	//
-	// https://github.com/boltdb/bolt/issues/284
-	NoGrowSync bool
-
-	// If you want to read the entire database fast, you can set MmapFlag to
-	// syscall.MAP_POPULATE on Linux 2.6.23+ for sequential read-ahead.
-	MmapFlags int
-
-	// MaxBatchSize is the maximum size of a batch. Default value is
-	// copied from DefaultMaxBatchSize in Open.
-	//
-	// If <=0, disables batching.
-	//
-	// Do not change concurrently with calls to Batch.
-	MaxBatchSize int
-
-	// MaxBatchDelay is the maximum delay before a batch starts.
-	// Default value is copied from DefaultMaxBatchDelay in Open.
-	//
-	// If <=0, effectively disables batching.
-	//
-	// Do not change concurrently with calls to Batch.
-	MaxBatchDelay time.Duration
-
-	// AllocSize is the amount of space allocated when the database
-	// needs to create new pages. This is done to amortize the cost
-	// of truncate() and fsync() when growing the data file.
-	AllocSize int
-
-	path     string
-	openFile func(string, int, os.FileMode) (*os.File, error)
-	file     *os.File
-	dataref  []byte // mmap'ed readonly, write throws SEGV
-	data     *[maxMapSize]byte
-	datasz   int
-	filesz   int // current on disk file size
-	meta0    *meta
-	meta1    *meta
-	pageSize int
-	opened   bool
-	rwtx     *Tx
-	txs      []*Tx
-	stats    Stats
-
-	freelist     *freelist
-	freelistLoad sync.Once
-
-	pagePool sync.Pool
-
-	batchMu sync.Mutex
-	batch   *batch
-
-	rwlock   sync.Mutex   // Allows only one writer at a time.
-	metalock sync.Mutex   // Protects meta page access.
-	mmaplock sync.RWMutex // Protects mmap access during remapping.
-	statlock sync.RWMutex // Protects stats access.
-
-	ops struct {
-		writeAt func(b []byte, off int64) (n int, err error)
-	}
-
-	// Read only mode.
-	// When true, Update() and Begin(true) return ErrDatabaseReadOnly immediately.
-	readOnly bool
-}
-
-// Path returns the path to currently open database file.
-func (db *DB) Path() string {
-	return db.path
-}
-
-// GoString returns the Go string representation of the database.
-func (db *DB) GoString() string {
-	return fmt.Sprintf("bolt.DB{path:%q}", db.path)
-}
-
-// String returns the string representation of the database.
-func (db *DB) String() string {
-	return fmt.Sprintf("DB<%q>", db.path)
-}
-
-// Open creates and opens a database at the given path.
-// If the file does not exist then it will be created automatically.
-// Passing in nil options will cause Bolt to open the database with the default options.
-func Open(path string, mode os.FileMode, options *Options) (*DB, error) {
-	db := &DB{
-		opened: true,
-	}
-	// Set default options if no options are provided.
-	if options == nil {
-		options = DefaultOptions
-	}
-	db.NoSync = options.NoSync
-	db.NoGrowSync = options.NoGrowSync
-	db.MmapFlags = options.MmapFlags
-	db.NoFreelistSync = options.NoFreelistSync
-	db.FreelistType = options.FreelistType
-
-	// Set default values for later DB operations.
-	db.MaxBatchSize = DefaultMaxBatchSize
-	db.MaxBatchDelay = DefaultMaxBatchDelay
-	db.AllocSize = DefaultAllocSize
-
-	flag := os.O_RDWR
-	if options.ReadOnly {
-		flag = os.O_RDONLY
-		db.readOnly = true
-	}
-
-	db.openFile = options.OpenFile
-	if db.openFile == nil {
-		db.openFile = os.OpenFile
-	}
-
-	// Open data file and separate sync handler for metadata writes.
-	db.path = path
-	var err error
-	if db.file, err = db.openFile(db.path, flag|os.O_CREATE, mode); err != nil {
-		_ = db.close()
-		return nil, err
-	}
-
-	// Lock file so that other processes using Bolt in read-write mode cannot
-	// use the database  at the same time. This would cause corruption since
-	// the two processes would write meta pages and free pages separately.
-	// The database file is locked exclusively (only one process can grab the lock)
-	// if !options.ReadOnly.
-	// The database file is locked using the shared lock (more than one process may
-	// hold a lock at the same time) otherwise (options.ReadOnly is set).
-	if err := flock(db, !db.readOnly, options.Timeout); err != nil {
-		_ = db.close()
-		return nil, err
-	}
-
-	// Default values for test hooks
-	db.ops.writeAt = db.file.WriteAt
-
-	if db.pageSize = options.PageSize; db.pageSize == 0 {
-		// Set the default page size to the OS page size.
-		db.pageSize = defaultPageSize
-	}
-
-	// Initialize the database if it doesn't exist.
-	if info, err := db.file.Stat(); err != nil {
-		_ = db.close()
-		return nil, err
-	} else if info.Size() == 0 {
-		// Initialize new files with meta pages.
-		if err := db.init(); err != nil {
-			// clean up file descriptor on initialization fail
-			_ = db.close()
-			return nil, err
-		}
-	} else {
-		// Read the first meta page to determine the page size.
-		var buf [0x1000]byte
-		// If we can't read the page size, but can read a page, assume
-		// it's the same as the OS or one given -- since that's how the
-		// page size was chosen in the first place.
-		//
-		// If the first page is invalid and this OS uses a different
-		// page size than what the database was created with then we
-		// are out of luck and cannot access the database.
-		//
-		// TODO: scan for next page
-		if bw, err := db.file.ReadAt(buf[:], 0); err == nil && bw == len(buf) {
-			if m := db.pageInBuffer(buf[:], 0).meta(); m.validate() == nil {
-				db.pageSize = int(m.pageSize)
-			}
-		} else {
-			_ = db.close()
-			return nil, ErrInvalid
-		}
-	}
-
-	// Initialize page pool.
-	db.pagePool = sync.Pool{
-		New: func() interface{} {
-			return make([]byte, db.pageSize)
-		},
-	}
-
-	// Memory map the data file.
-	if err := db.mmap(options.InitialMmapSize); err != nil {
-		_ = db.close()
-		return nil, err
-	}
-
-	if db.readOnly {
-		return db, nil
-	}
-
-	db.loadFreelist()
-
-	// Flush freelist when transitioning from no sync to sync so
-	// NoFreelistSync unaware boltdb can open the db later.
-	if !db.NoFreelistSync && !db.hasSyncedFreelist() {
-		tx, err := db.Begin(true)
-		if tx != nil {
-			err = tx.Commit()
-		}
-		if err != nil {
-			_ = db.close()
-			return nil, err
-		}
-	}
-
-	// Mark the database as opened and return.
-	return db, nil
-}
-
-// loadFreelist reads the freelist if it is synced, or reconstructs it
-// by scanning the DB if it is not synced. It assumes there are no
-// concurrent accesses being made to the freelist.
-func (db *DB) loadFreelist() {
-	db.freelistLoad.Do(func() {
-		db.freelist = newFreelist(db.FreelistType)
-		if !db.hasSyncedFreelist() {
-			// Reconstruct free list by scanning the DB.
-			db.freelist.readIDs(db.freepages())
-		} else {
-			// Read free list from freelist page.
-			db.freelist.read(db.page(db.meta().freelist))
-		}
-		db.stats.FreePageN = db.freelist.free_count()
-	})
-}
-
-func (db *DB) hasSyncedFreelist() bool {
-	return db.meta().freelist != pgidNoFreelist
-}
-
-// mmap opens the underlying memory-mapped file and initializes the meta references.
-// minsz is the minimum size that the new mmap can be.
-func (db *DB) mmap(minsz int) error {
-	db.mmaplock.Lock()
-	defer db.mmaplock.Unlock()
-
-	info, err := db.file.Stat()
-	if err != nil {
-		return fmt.Errorf("mmap stat error: %s", err)
-	} else if int(info.Size()) < db.pageSize*2 {
-		return fmt.Errorf("file size too small")
-	}
-
-	// Ensure the size is at least the minimum size.
-	var size = int(info.Size())
-	if size < minsz {
-		size = minsz
-	}
-	size, err = db.mmapSize(size)
-	if err != nil {
-		return err
-	}
-
-	// Dereference all mmap references before unmapping.
-	if db.rwtx != nil {
-		db.rwtx.root.dereference()
-	}
-
-	// Unmap existing data before continuing.
-	if err := db.munmap(); err != nil {
-		return err
-	}
-
-	// Memory-map the data file as a byte slice.
-	if err := mmap(db, size); err != nil {
-		return err
-	}
-
-	// Save references to the meta pages.
-	db.meta0 = db.page(0).meta()
-	db.meta1 = db.page(1).meta()
-
-	// Validate the meta pages. We only return an error if both meta pages fail
-	// validation, since meta0 failing validation means that it wasn't saved
-	// properly -- but we can recover using meta1. And vice-versa.
-	err0 := db.meta0.validate()
-	err1 := db.meta1.validate()
-	if err0 != nil && err1 != nil {
-		return err0
-	}
-
-	return nil
-}
-
-// munmap unmaps the data file from memory.
-func (db *DB) munmap() error {
-	if err := munmap(db); err != nil {
-		return fmt.Errorf("unmap error: " + err.Error())
-	}
-	return nil
-}
-
-// mmapSize determines the appropriate size for the mmap given the current size
-// of the database. The minimum size is 32KB and doubles until it reaches 1GB.
-// Returns an error if the new mmap size is greater than the max allowed.
-func (db *DB) mmapSize(size int) (int, error) {
-	// Double the size from 32KB until 1GB.
-	for i := uint(15); i <= 30; i++ {
-		if size <= 1<<i {
-			return 1 << i, nil
-		}
-	}
-
-	// Verify the requested size is not above the maximum allowed.
-	if size > maxMapSize {
-		return 0, fmt.Errorf("mmap too large")
-	}
-
-	// If larger than 1GB then grow by 1GB at a time.
-	sz := int64(size)
-	if remainder := sz % int64(maxMmapStep); remainder > 0 {
-		sz += int64(maxMmapStep) - remainder
-	}
-
-	// Ensure that the mmap size is a multiple of the page size.
-	// This should always be true since we're incrementing in MBs.
-	pageSize := int64(db.pageSize)
-	if (sz % pageSize) != 0 {
-		sz = ((sz / pageSize) + 1) * pageSize
-	}
-
-	// If we've exceeded the max size then only grow up to the max size.
-	if sz > maxMapSize {
-		sz = maxMapSize
-	}
-
-	return int(sz), nil
-}
-
-// init creates a new database file and initializes its meta pages.
-func (db *DB) init() error {
-	// Create two meta pages on a buffer.
-	buf := make([]byte, db.pageSize*4)
-	for i := 0; i < 2; i++ {
-		p := db.pageInBuffer(buf[:], pgid(i))
-		p.id = pgid(i)
-		p.flags = metaPageFlag
-
-		// Initialize the meta page.
-		m := p.meta()
-		m.magic = magic
-		m.version = version
-		m.pageSize = uint32(db.pageSize)
-		m.freelist = 2
-		m.root = bucket{root: 3}
-		m.pgid = 4
-		m.txid = txid(i)
-		m.checksum = m.sum64()
-	}
-
-	// Write an empty freelist at page 3.
-	p := db.pageInBuffer(buf[:], pgid(2))
-	p.id = pgid(2)
-	p.flags = freelistPageFlag
-	p.count = 0
-
-	// Write an empty leaf page at page 4.
-	p = db.pageInBuffer(buf[:], pgid(3))
-	p.id = pgid(3)
-	p.flags = leafPageFlag
-	p.count = 0
-
-	// Write the buffer to our data file.
-	if _, err := db.ops.writeAt(buf, 0); err != nil {
-		return err
-	}
-	if err := fdatasync(db); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-// Close releases all database resources.
-// It will block waiting for any open transactions to finish
-// before closing the database and returning.
-func (db *DB) Close() error {
-	db.rwlock.Lock()
-	defer db.rwlock.Unlock()
-
-	db.metalock.Lock()
-	defer db.metalock.Unlock()
-
-	db.mmaplock.Lock()
-	defer db.mmaplock.Unlock()
-
-	return db.close()
-}
-
-func (db *DB) close() error {
-	if !db.opened {
-		return nil
-	}
-
-	db.opened = false
-
-	db.freelist = nil
-
-	// Clear ops.
-	db.ops.writeAt = nil
-
-	// Close the mmap.
-	if err := db.munmap(); err != nil {
-		return err
-	}
-
-	// Close file handles.
-	if db.file != nil {
-		// No need to unlock read-only file.
-		if !db.readOnly {
-			// Unlock the file.
-			if err := funlock(db); err != nil {
-				log.Printf("bolt.Close(): funlock error: %s", err)
-			}
-		}
-
-		// Close the file descriptor.
-		if err := db.file.Close(); err != nil {
-			return fmt.Errorf("db file close: %s", err)
-		}
-		db.file = nil
-	}
-
-	db.path = ""
-	return nil
-}
-
-// Begin starts a new transaction.
-// Multiple read-only transactions can be used concurrently but only one
-// write transaction can be used at a time. Starting multiple write transactions
-// will cause the calls to block and be serialized until the current write
-// transaction finishes.
-//
-// Transactions should not be dependent on one another. Opening a read
-// transaction and a write transaction in the same goroutine can cause the
-// writer to deadlock because the database periodically needs to re-mmap itself
-// as it grows and it cannot do that while a read transaction is open.
-//
-// If a long running read transaction (for example, a snapshot transaction) is
-// needed, you might want to set DB.InitialMmapSize to a large enough value
-// to avoid potential blocking of write transaction.
-//
-// IMPORTANT: You must close read-only transactions after you are finished or
-// else the database will not reclaim old pages.
-func (db *DB) Begin(writable bool) (*Tx, error) {
-	if writable {
-		return db.beginRWTx()
-	}
-	return db.beginTx()
-}
-
-func (db *DB) beginTx() (*Tx, error) {
-	// Lock the meta pages while we initialize the transaction. We obtain
-	// the meta lock before the mmap lock because that's the order that the
-	// write transaction will obtain them.
-	db.metalock.Lock()
-
-	// Obtain a read-only lock on the mmap. When the mmap is remapped it will
-	// obtain a write lock so all transactions must finish before it can be
-	// remapped.
-	db.mmaplock.RLock()
-
-	// Exit if the database is not open yet.
-	if !db.opened {
-		db.mmaplock.RUnlock()
-		db.metalock.Unlock()
-		return nil, ErrDatabaseNotOpen
-	}
-
-	// Create a transaction associated with the database.
-	t := &Tx{}
-	t.init(db)
-
-	// Keep track of transaction until it closes.
-	db.txs = append(db.txs, t)
-	n := len(db.txs)
-
-	// Unlock the meta pages.
-	db.metalock.Unlock()
-
-	// Update the transaction stats.
-	db.statlock.Lock()
-	db.stats.TxN++
-	db.stats.OpenTxN = n
-	db.statlock.Unlock()
-
-	return t, nil
-}
-
-func (db *DB) beginRWTx() (*Tx, error) {
-	// If the database was opened with Options.ReadOnly, return an error.
-	if db.readOnly {
-		return nil, ErrDatabaseReadOnly
-	}
-
-	// Obtain writer lock. This is released by the transaction when it closes.
-	// This enforces only one writer transaction at a time.
-	db.rwlock.Lock()
-
-	// Once we have the writer lock then we can lock the meta pages so that
-	// we can set up the transaction.
-	db.metalock.Lock()
-	defer db.metalock.Unlock()
-
-	// Exit if the database is not open yet.
-	if !db.opened {
-		db.rwlock.Unlock()
-		return nil, ErrDatabaseNotOpen
-	}
-
-	// Create a transaction associated with the database.
-	t := &Tx{writable: true}
-	t.init(db)
-	db.rwtx = t
-	db.freePages()
-	return t, nil
-}
-
-// freePages releases any pages associated with closed read-only transactions.
-func (db *DB) freePages() {
-	// Free all pending pages prior to earliest open transaction.
-	sort.Sort(txsById(db.txs))
-	minid := txid(0xFFFFFFFFFFFFFFFF)
-	if len(db.txs) > 0 {
-		minid = db.txs[0].meta.txid
-	}
-	if minid > 0 {
-		db.freelist.release(minid - 1)
-	}
-	// Release unused txid extents.
-	for _, t := range db.txs {
-		db.freelist.releaseRange(minid, t.meta.txid-1)
-		minid = t.meta.txid + 1
-	}
-	db.freelist.releaseRange(minid, txid(0xFFFFFFFFFFFFFFFF))
-	// Any page both allocated and freed in an extent is safe to release.
-}
-
-type txsById []*Tx
-
-func (t txsById) Len() int           { return len(t) }
-func (t txsById) Swap(i, j int)      { t[i], t[j] = t[j], t[i] }
-func (t txsById) Less(i, j int) bool { return t[i].meta.txid < t[j].meta.txid }
-
-// removeTx removes a transaction from the database.
-func (db *DB) removeTx(tx *Tx) {
-	// Release the read lock on the mmap.
-	db.mmaplock.RUnlock()
-
-	// Use the meta lock to restrict access to the DB object.
-	db.metalock.Lock()
-
-	// Remove the transaction.
-	for i, t := range db.txs {
-		if t == tx {
-			last := len(db.txs) - 1
-			db.txs[i] = db.txs[last]
-			db.txs[last] = nil
-			db.txs = db.txs[:last]
-			break
-		}
-	}
-	n := len(db.txs)
-
-	// Unlock the meta pages.
-	db.metalock.Unlock()
-
-	// Merge statistics.
-	db.statlock.Lock()
-	db.stats.OpenTxN = n
-	db.stats.TxStats.add(&tx.stats)
-	db.statlock.Unlock()
-}
-
-// Update executes a function within the context of a read-write managed transaction.
-// If no error is returned from the function then the transaction is committed.
-// If an error is returned then the entire transaction is rolled back.
-// Any error that is returned from the function or returned from the commit is
-// returned from the Update() method.
-//
-// Attempting to manually commit or rollback within the function will cause a panic.
-func (db *DB) Update(fn func(*Tx) error) error {
-	t, err := db.Begin(true)
-	if err != nil {
-		return err
-	}
-
-	// Make sure the transaction rolls back in the event of a panic.
-	defer func() {
-		if t.db != nil {
-			t.rollback()
-		}
-	}()
-
-	// Mark as a managed tx so that the inner function cannot manually commit.
-	t.managed = true
-
-	// If an error is returned from the function then rollback and return error.
-	err = fn(t)
-	t.managed = false
-	if err != nil {
-		_ = t.Rollback()
-		return err
-	}
-
-	return t.Commit()
-}
-
-// View executes a function within the context of a managed read-only transaction.
-// Any error that is returned from the function is returned from the View() method.
-//
-// Attempting to manually rollback within the function will cause a panic.
-func (db *DB) View(fn func(*Tx) error) error {
-	t, err := db.Begin(false)
-	if err != nil {
-		return err
-	}
-
-	// Make sure the transaction rolls back in the event of a panic.
-	defer func() {
-		if t.db != nil {
-			t.rollback()
-		}
-	}()
-
-	// Mark as a managed tx so that the inner function cannot manually rollback.
-	t.managed = true
-
-	// If an error is returned from the function then pass it through.
-	err = fn(t)
-	t.managed = false
-	if err != nil {
-		_ = t.Rollback()
-		return err
-	}
-
-	return t.Rollback()
-}
-
-// Batch calls fn as part of a batch. It behaves similar to Update,
-// except:
-//
-// 1. concurrent Batch calls can be combined into a single Bolt
-// transaction.
-//
-// 2. the function passed to Batch may be called multiple times,
-// regardless of whether it returns error or not.
-//
-// This means that Batch function side effects must be idempotent and
-// take permanent effect only after a successful return is seen in
-// caller.
-//
-// The maximum batch size and delay can be adjusted with DB.MaxBatchSize
-// and DB.MaxBatchDelay, respectively.
-//
-// Batch is only useful when there are multiple goroutines calling it.
-func (db *DB) Batch(fn func(*Tx) error) error {
-	errCh := make(chan error, 1)
-
-	db.batchMu.Lock()
-	if (db.batch == nil) || (db.batch != nil && len(db.batch.calls) >= db.MaxBatchSize) {
-		// There is no existing batch, or the existing batch is full; start a new one.
-		db.batch = &batch{
-			db: db,
-		}
-		db.batch.timer = time.AfterFunc(db.MaxBatchDelay, db.batch.trigger)
-	}
-	db.batch.calls = append(db.batch.calls, call{fn: fn, err: errCh})
-	if len(db.batch.calls) >= db.MaxBatchSize {
-		// wake up batch, it's ready to run
-		go db.batch.trigger()
-	}
-	db.batchMu.Unlock()
-
-	err := <-errCh
-	if err == trySolo {
-		err = db.Update(fn)
-	}
-	return err
-}
-
-type call struct {
-	fn  func(*Tx) error
-	err chan<- error
-}
-
-type batch struct {
-	db    *DB
-	timer *time.Timer
-	start sync.Once
-	calls []call
-}
-
-// trigger runs the batch if it hasn't already been run.
-func (b *batch) trigger() {
-	b.start.Do(b.run)
-}
-
-// run performs the transactions in the batch and communicates results
-// back to DB.Batch.
-func (b *batch) run() {
-	b.db.batchMu.Lock()
-	b.timer.Stop()
-	// Make sure no new work is added to this batch, but don't break
-	// other batches.
-	if b.db.batch == b {
-		b.db.batch = nil
-	}
-	b.db.batchMu.Unlock()
-
-retry:
-	for len(b.calls) > 0 {
-		var failIdx = -1
-		err := b.db.Update(func(tx *Tx) error {
-			for i, c := range b.calls {
-				if err := safelyCall(c.fn, tx); err != nil {
-					failIdx = i
-					return err
-				}
-			}
-			return nil
-		})
-
-		if failIdx >= 0 {
-			// take the failing transaction out of the batch. it's
-			// safe to shorten b.calls here because db.batch no longer
-			// points to us, and we hold the mutex anyway.
-			c := b.calls[failIdx]
-			b.calls[failIdx], b.calls = b.calls[len(b.calls)-1], b.calls[:len(b.calls)-1]
-			// tell the submitter re-run it solo, continue with the rest of the batch
-			c.err <- trySolo
-			continue retry
-		}
-
-		// pass success, or bolt internal errors, to all callers
-		for _, c := range b.calls {
-			c.err <- err
-		}
-		break retry
-	}
-}
-
-// trySolo is a special sentinel error value used for signaling that a
-// transaction function should be re-run. It should never be seen by
-// callers.
-var trySolo = errors.New("batch function returned an error and should be re-run solo")
-
-type panicked struct {
-	reason interface{}
-}
-
-func (p panicked) Error() string {
-	if err, ok := p.reason.(error); ok {
-		return err.Error()
-	}
-	return fmt.Sprintf("panic: %v", p.reason)
-}
-
-func safelyCall(fn func(*Tx) error, tx *Tx) (err error) {
-	defer func() {
-		if p := recover(); p != nil {
-			err = panicked{p}
-		}
-	}()
-	return fn(tx)
-}
-
-// Sync executes fdatasync() against the database file handle.
-//
-// This is not necessary under normal operation, however, if you use NoSync
-// then it allows you to force the database file to sync against the disk.
-func (db *DB) Sync() error { return fdatasync(db) }
-
-// Stats retrieves ongoing performance stats for the database.
-// This is only updated when a transaction closes.
-func (db *DB) Stats() Stats {
-	db.statlock.RLock()
-	defer db.statlock.RUnlock()
-	return db.stats
-}
-
-// This is for internal access to the raw data bytes from the C cursor, use
-// carefully, or not at all.
-func (db *DB) Info() *Info {
-	return &Info{uintptr(unsafe.Pointer(&db.data[0])), db.pageSize}
-}
-
-// page retrieves a page reference from the mmap based on the current page size.
-func (db *DB) page(id pgid) *page {
-	pos := id * pgid(db.pageSize)
-	return (*page)(unsafe.Pointer(&db.data[pos]))
-}
-
-// pageInBuffer retrieves a page reference from a given byte array based on the current page size.
-func (db *DB) pageInBuffer(b []byte, id pgid) *page {
-	return (*page)(unsafe.Pointer(&b[id*pgid(db.pageSize)]))
-}
-
-// meta retrieves the current meta page reference.
-func (db *DB) meta() *meta {
-	// We have to return the meta with the highest txid which doesn't fail
-	// validation. Otherwise, we can cause errors when in fact the database is
-	// in a consistent state. metaA is the one with the higher txid.
-	metaA := db.meta0
-	metaB := db.meta1
-	if db.meta1.txid > db.meta0.txid {
-		metaA = db.meta1
-		metaB = db.meta0
-	}
-
-	// Use higher meta page if valid. Otherwise fallback to previous, if valid.
-	if err := metaA.validate(); err == nil {
-		return metaA
-	} else if err := metaB.validate(); err == nil {
-		return metaB
-	}
-
-	// This should never be reached, because both meta1 and meta0 were validated
-	// on mmap() and we do fsync() on every write.
-	panic("bolt.DB.meta(): invalid meta pages")
-}
-
-// allocate returns a contiguous block of memory starting at a given page.
-func (db *DB) allocate(txid txid, count int) (*page, error) {
-	// Allocate a temporary buffer for the page.
-	var buf []byte
-	if count == 1 {
-		buf = db.pagePool.Get().([]byte)
-	} else {
-		buf = make([]byte, count*db.pageSize)
-	}
-	p := (*page)(unsafe.Pointer(&buf[0]))
-	p.overflow = uint32(count - 1)
-
-	// Use pages from the freelist if they are available.
-	if p.id = db.freelist.allocate(txid, count); p.id != 0 {
-		return p, nil
-	}
-
-	// Resize mmap() if we're at the end.
-	p.id = db.rwtx.meta.pgid
-	var minsz = int((p.id+pgid(count))+1) * db.pageSize
-	if minsz >= db.datasz {
-		if err := db.mmap(minsz); err != nil {
-			return nil, fmt.Errorf("mmap allocate error: %s", err)
-		}
-	}
-
-	// Move the page id high water mark.
-	db.rwtx.meta.pgid += pgid(count)
-
-	return p, nil
-}
-
-// grow grows the size of the database to the given sz.
-func (db *DB) grow(sz int) error {
-	// Ignore if the new size is less than available file size.
-	if sz <= db.filesz {
-		return nil
-	}
-
-	// If the data is smaller than the alloc size then only allocate what's needed.
-	// Once it goes over the allocation size then allocate in chunks.
-	if db.datasz < db.AllocSize {
-		sz = db.datasz
-	} else {
-		sz += db.AllocSize
-	}
-
-	// Truncate and fsync to ensure file size metadata is flushed.
-	// https://github.com/boltdb/bolt/issues/284
-	if !db.NoGrowSync && !db.readOnly {
-		if runtime.GOOS != "windows" {
-			if err := db.file.Truncate(int64(sz)); err != nil {
-				return fmt.Errorf("file resize error: %s", err)
-			}
-		}
-		if err := db.file.Sync(); err != nil {
-			return fmt.Errorf("file sync error: %s", err)
-		}
-	}
-
-	db.filesz = sz
-	return nil
-}
-
-func (db *DB) IsReadOnly() bool {
-	return db.readOnly
-}
-
-func (db *DB) freepages() []pgid {
-	tx, err := db.beginTx()
-	defer func() {
-		err = tx.Rollback()
-		if err != nil {
-			panic("freepages: failed to rollback tx")
-		}
-	}()
-	if err != nil {
-		panic("freepages: failed to open read only tx")
-	}
-
-	reachable := make(map[pgid]*page)
-	nofreed := make(map[pgid]bool)
-	ech := make(chan error)
-	go func() {
-		for e := range ech {
-			panic(fmt.Sprintf("freepages: failed to get all reachable pages (%v)", e))
-		}
-	}()
-	tx.checkBucket(&tx.root, reachable, nofreed, ech)
-	close(ech)
-
-	var fids []pgid
-	for i := pgid(2); i < db.meta().pgid; i++ {
-		if _, ok := reachable[i]; !ok {
-			fids = append(fids, i)
-		}
-	}
-	return fids
-}
-
-// Options represents the options that can be set when opening a database.
-type Options struct {
-	// Timeout is the amount of time to wait to obtain a file lock.
-	// When set to zero it will wait indefinitely. This option is only
-	// available on Darwin and Linux.
-	Timeout time.Duration
-
-	// Sets the DB.NoGrowSync flag before memory mapping the file.
-	NoGrowSync bool
-
-	// Do not sync freelist to disk. This improves the database write performance
-	// under normal operation, but requires a full database re-sync during recovery.
-	NoFreelistSync bool
-
-	// FreelistType sets the backend freelist type. There are two options. Array which is simple but endures
-	// dramatic performance degradation if database is large and framentation in freelist is common.
-	// The alternative one is using hashmap, it is faster in almost all circumstances
-	// but it doesn't guarantee that it offers the smallest page id available. In normal case it is safe.
-	// The default type is array
-	FreelistType FreelistType
-
-	// Open database in read-only mode. Uses flock(..., LOCK_SH |LOCK_NB) to
-	// grab a shared lock (UNIX).
-	ReadOnly bool
-
-	// Sets the DB.MmapFlags flag before memory mapping the file.
-	MmapFlags int
-
-	// InitialMmapSize is the initial mmap size of the database
-	// in bytes. Read transactions won't block write transaction
-	// if the InitialMmapSize is large enough to hold database mmap
-	// size. (See DB.Begin for more information)
-	//
-	// If <=0, the initial map size is 0.
-	// If initialMmapSize is smaller than the previous database size,
-	// it takes no effect.
-	InitialMmapSize int
-
-	// PageSize overrides the default OS page size.
-	PageSize int
-
-	// NoSync sets the initial value of DB.NoSync. Normally this can just be
-	// set directly on the DB itself when returned from Open(), but this option
-	// is useful in APIs which expose Options but not the underlying DB.
-	NoSync bool
-
-	// OpenFile is used to open files. It defaults to os.OpenFile. This option
-	// is useful for writing hermetic tests.
-	OpenFile func(string, int, os.FileMode) (*os.File, error)
-}
-
-// DefaultOptions represent the options used if nil options are passed into Open().
-// No timeout is used which will cause Bolt to wait indefinitely for a lock.
-var DefaultOptions = &Options{
-	Timeout:      0,
-	NoGrowSync:   false,
-	FreelistType: FreelistArrayType,
-}
-
-// Stats represents statistics about the database.
-type Stats struct {
-	// Freelist stats
-	FreePageN     int // total number of free pages on the freelist
-	PendingPageN  int // total number of pending pages on the freelist
-	FreeAlloc     int // total bytes allocated in free pages
-	FreelistInuse int // total bytes used by the freelist
-
-	// Transaction stats
-	TxN     int // total number of started read transactions
-	OpenTxN int // number of currently open read transactions
-
-	TxStats TxStats // global, ongoing stats.
-}
-
-// Sub calculates and returns the difference between two sets of database 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 *Stats) Sub(other *Stats) Stats {
-	if other == nil {
-		return *s
-	}
-	var diff Stats
-	diff.FreePageN = s.FreePageN
-	diff.PendingPageN = s.PendingPageN
-	diff.FreeAlloc = s.FreeAlloc
-	diff.FreelistInuse = s.FreelistInuse
-	diff.TxN = s.TxN - other.TxN
-	diff.TxStats = s.TxStats.Sub(&other.TxStats)
-	return diff
-}
-
-type Info struct {
-	Data     uintptr
-	PageSize int
-}
-
-type meta struct {
-	magic    uint32
-	version  uint32
-	pageSize uint32
-	flags    uint32
-	root     bucket
-	freelist pgid
-	pgid     pgid
-	txid     txid
-	checksum uint64
-}
-
-// validate checks the marker bytes and version of the meta page to ensure it matches this binary.
-func (m *meta) validate() error {
-	if m.magic != magic {
-		return ErrInvalid
-	} else if m.version != version {
-		return ErrVersionMismatch
-	} else if m.checksum != 0 && m.checksum != m.sum64() {
-		return ErrChecksum
-	}
-	return nil
-}
-
-// copy copies one meta object to another.
-func (m *meta) copy(dest *meta) {
-	*dest = *m
-}
-
-// write writes the meta onto a page.
-func (m *meta) write(p *page) {
-	if m.root.root >= m.pgid {
-		panic(fmt.Sprintf("root bucket pgid (%d) above high water mark (%d)", m.root.root, m.pgid))
-	} else if m.freelist >= m.pgid && m.freelist != pgidNoFreelist {
-		// TODO: reject pgidNoFreeList if !NoFreelistSync
-		panic(fmt.Sprintf("freelist pgid (%d) above high water mark (%d)", m.freelist, m.pgid))
-	}
-
-	// Page id is either going to be 0 or 1 which we can determine by the transaction ID.
-	p.id = pgid(m.txid % 2)
-	p.flags |= metaPageFlag
-
-	// Calculate the checksum.
-	m.checksum = m.sum64()
-
-	m.copy(p.meta())
-}
-
-// generates the checksum for the meta.
-func (m *meta) sum64() uint64 {
-	var h = fnv.New64a()
-	_, _ = h.Write((*[unsafe.Offsetof(meta{}.checksum)]byte)(unsafe.Pointer(m))[:])
-	return h.Sum64()
-}
-
-// _assert will panic with a given formatted message if the given condition is false.
-func _assert(condition bool, msg string, v ...interface{}) {
-	if !condition {
-		panic(fmt.Sprintf("assertion failed: "+msg, v...))
-	}
-}