/
changeset.go
363 lines (318 loc) · 8.37 KB
/
changeset.go
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package client
import (
"bufio"
"compress/zlib"
"encoding/binary"
"fmt"
"io"
"math/bits"
"os"
"sort"
"strings"
"github.com/cosmos/iavl"
"github.com/golang/snappy"
)
const (
ZlibFileSuffix = ".zz"
SnappyFileSuffix = ".snappy"
)
// WriteChangeSet writes a version of change sets to writer.
//
// Change set file format:
// ```
// version: int64
// size: int64 // size of whole payload
// payload:
//
// delete: int8
// keyLen: varint-uint64
// key
// [ // if delete is false
// valueLen: varint-uint64
// value
// ]
// repeat with next key-value pair
//
// repeat with next version
// ```
func WriteChangeSet(writer io.Writer, version int64, cs iavl.ChangeSet) error {
var size int
items := make([][]byte, 0, len(cs.Pairs))
for _, pair := range cs.Pairs {
buf, err := encodeKVPair(pair)
if err != nil {
return err
}
size += len(buf)
items = append(items, buf)
}
var versionHeader [16]byte
binary.LittleEndian.PutUint64(versionHeader[:], uint64(version))
binary.LittleEndian.PutUint64(versionHeader[8:], uint64(size))
if _, err := writer.Write(versionHeader[:]); err != nil {
return err
}
for _, item := range items {
if _, err := writer.Write(item); err != nil {
return err
}
}
return nil
}
// ReadChangeSet decode a version of change set from reader.
// if parseChangeset is false, it'll skip change set payload directly.
//
// returns (version, number of bytes read, changeSet, err)
func ReadChangeSet(reader Reader, parseChangeset bool) (int64, int64, *iavl.ChangeSet, error) {
var versionHeader [16]byte
if _, err := io.ReadFull(reader, versionHeader[:]); err != nil {
return 0, 0, nil, err
}
version := binary.LittleEndian.Uint64(versionHeader[:8])
size := int64(binary.LittleEndian.Uint64(versionHeader[8:16]))
var changeSet iavl.ChangeSet
if size == 0 {
return int64(version), 16, &changeSet, nil
}
if parseChangeset {
var offset int64
for offset < size {
pair, err := readKVPair(reader)
if err != nil {
return 0, 0, nil, err
}
offset += int64(encodedSizeOfKVPair(pair))
changeSet.Pairs = append(changeSet.Pairs, pair)
}
if offset != size {
return 0, 0, nil, fmt.Errorf("read beyond payload size limit, size: %d, offset: %d", size, offset)
}
} else {
if _, err := io.CopyN(io.Discard, reader, size); err != nil {
return 0, 0, nil, err
}
}
return int64(version), size + 16, &changeSet, nil
}
// encodedSizeOfKVPair returns the encoded length of a key-value pair
//
// layout: deletion(1) + keyLen(varint) + key + [ valueLen(varint) + value ]
func encodedSizeOfKVPair(pair *iavl.KVPair) int {
keyLen := len(pair.Key)
size := 1 + uvarintSize(uint64(keyLen)) + keyLen
if pair.Delete {
return size
}
valueLen := len(pair.Value)
return size + uvarintSize(uint64(valueLen)) + valueLen
}
// encodeKVPair encode a key-value pair in change set.
// see godoc of `encodedSizeOfKVPair` for layout description,
// returns error if key/value length overflows.
func encodeKVPair(pair *iavl.KVPair) ([]byte, error) {
buf := make([]byte, encodedSizeOfKVPair(pair))
offset := 1
keyLen := len(pair.Key)
offset += binary.PutUvarint(buf[offset:], uint64(keyLen))
copy(buf[offset:], pair.Key)
if pair.Delete {
buf[0] = 1
return buf, nil
}
offset += keyLen
offset += binary.PutUvarint(buf[offset:], uint64(len(pair.Value)))
copy(buf[offset:], pair.Value)
return buf, nil
}
// Reader combines `io.Reader` and `io.ByteReader`.
type Reader interface {
io.Reader
io.ByteReader
}
// ReadCloser combines `Reader` and `io.Closer`.
type ReadCloser interface {
Reader
io.Closer
}
// readKVPair decode a key-value pair from reader
//
// see godoc of `encodedSizeOfKVPair` for layout description
func readKVPair(reader Reader) (*iavl.KVPair, error) {
deletion, err := reader.ReadByte()
if err != nil {
return nil, err
}
keyLen, err := binary.ReadUvarint(reader)
if err != nil {
return nil, err
}
pair := iavl.KVPair{
Delete: deletion == 1,
Key: make([]byte, keyLen),
}
if _, err := io.ReadFull(reader, pair.Key); err != nil {
return nil, err
}
if pair.Delete {
return &pair, nil
}
valueLen, err := binary.ReadUvarint(reader)
if err != nil {
return nil, err
}
pair.Value = make([]byte, valueLen)
if _, err := io.ReadFull(reader, pair.Value); err != nil {
return nil, err
}
return &pair, nil
}
// openChangeSetFile opens change set file,
// it handles compressed files automatically,
// also supports special name "-" to specify stdin.
func openChangeSetFile(fileName string) (ReadCloser, error) {
if fileName == "-" {
return WrapReader(bufio.NewReader(os.Stdin), nil), nil
}
var reader Reader
fp, err := os.Open(fileName)
if err != nil {
return nil, err
}
switch {
case strings.HasSuffix(fileName, ZlibFileSuffix):
zreader, err := zlib.NewReader(fp)
if err != nil {
_ = fp.Close()
return nil, err
}
reader = bufio.NewReader(zreader)
case strings.HasSuffix(fileName, SnappyFileSuffix):
reader = snappy.NewReader(fp)
default:
reader = bufio.NewReader(fp)
}
return WrapReader(reader, fp), nil
}
// withChangeSetFile opens change set file and pass the reader to callback,
// it closes the file immediately after callback returns.
func withChangeSetFile(fileName string, fn func(Reader) error) error {
reader, err := openChangeSetFile(fileName)
if err != nil {
return err
}
defer reader.Close()
return fn(reader)
}
// IterateChangeSets iterate the change set files,
func IterateChangeSets(
reader Reader,
fn func(version int64, changeSet *iavl.ChangeSet) (bool, error),
) (int64, error) {
var (
cont = true
lastCompleteOffset int64
version, offset int64
changeSet *iavl.ChangeSet
err error
)
for cont {
version, offset, changeSet, err = ReadChangeSet(reader, true)
if err != nil {
break
}
cont, err = fn(version, changeSet)
if err != nil {
break
}
lastCompleteOffset += offset
}
if err == io.EOF {
// it's not easy to distinguish normal EOF or unexpected EOF,
// there could be potential corrupted end of file and the err is a normal io.EOF here,
// user should verify the change set files in advance, using the verify command.
err = nil
}
return lastCompleteOffset, err
}
// IterateVersions iterate the version numbers in change set files, skipping the change set payloads.
func IterateVersions(
reader Reader,
fn func(version int64) (bool, error),
) (int64, error) {
var (
cont = true
lastCompleteOffset int64
version, offset int64
err error
)
for cont {
version, offset, _, err = ReadChangeSet(reader, false)
if err != nil {
break
}
cont, err = fn(version)
if err != nil {
break
}
lastCompleteOffset += offset
}
if err == io.EOF {
// it's not easy to distinguish normal EOF or unexpected EOF,
// there could be potential corrupted end of file and the err is a normal io.EOF here,
// user should verify the change set files in advance, using the verify command.
err = nil
}
return lastCompleteOffset, err
}
type FileWithVersion struct {
FileName string
Version uint64
}
// SortFilesByFirstVerson parse the first version of the change set files and associate with the file name,
// then sort them by version number, also filter out empty files.
func SortFilesByFirstVerson(files []string) ([]FileWithVersion, error) {
nonEmptyFiles := make([]FileWithVersion, 0, len(files))
for _, fileName := range files {
version, err := ReadFirstVersion(fileName)
if err != nil {
if err == io.EOF {
// skipping empty files
continue
}
return nil, err
}
nonEmptyFiles = append(nonEmptyFiles, FileWithVersion{
FileName: fileName,
Version: version,
})
}
sort.Slice(nonEmptyFiles, func(i, j int) bool {
return nonEmptyFiles[i].Version < nonEmptyFiles[j].Version
})
return nonEmptyFiles, nil
}
// ReadFirstVersion parse the first version number in the change set file
func ReadFirstVersion(fileName string) (uint64, error) {
fp, err := openChangeSetFile(fileName)
if err != nil {
return 0, err
}
defer fp.Close()
// parse the first version number
var versionBuf [8]byte
_, err = io.ReadFull(fp, versionBuf[:])
if err != nil {
return 0, err
}
return binary.LittleEndian.Uint64(versionBuf[:]), nil
}
// uvarintSize returns the size (in bytes) of uint64 encoded with the `binary.PutUvarint`.
func uvarintSize(num uint64) int {
bits := bits.Len64(num)
q, r := bits/7, bits%7
size := q
if r > 0 || size == 0 {
size++
}
return size
}