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mvcc.go
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mvcc.go
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// Copyright Fuzamei Corp. 2018 All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package db
import (
"bytes"
"strconv"
log "github.com/33cn/chain33/common/log/log15"
"github.com/33cn/chain33/types"
)
var mvccPrefix = []byte(".-mvcc-.")
var mvccMeta = append(mvccPrefix, []byte("m.")...)
var mvccData = append(mvccPrefix, []byte("d.")...)
var mvccLast = append(mvccPrefix, []byte("l.")...)
var mvccMetaVersion = append(mvccMeta, []byte("version.")...)
var mvccMetaVersionKeyList = append(mvccMeta, []byte("versionkl.")...)
//MVCC mvcc interface
type MVCC interface {
MVCCKV
SetVersion(hash []byte, version int64) error
DelVersion(hash []byte) error
GetVersion(hash []byte) (int64, error)
GetV(key []byte, version int64) ([]byte, error)
SetV(key []byte, value []byte, version int64) error
DelV(key []byte, version int64) error
AddMVCC(kvs []*types.KeyValue, hash []byte, prevHash []byte, version int64) ([]*types.KeyValue, error)
DelMVCC(hash []byte, version int64, strict bool) ([]*types.KeyValue, error)
GetMaxVersion() (int64, error)
GetVersionHash(version int64) ([]byte, error)
//回收: 某个版本之前的所有数据
//1. 保证有一个最新版本
//2. 这个操作回遍历所有的key所以比较慢
Trash(version int64) error
}
//MVCCKV only return kv when change database
type MVCCKV interface {
GetSaveKV(key []byte, value []byte, version int64) (*types.KeyValue, error)
GetDelKV(key []byte, version int64) (*types.KeyValue, error)
SetVersionKV(hash []byte, version int64) ([]*types.KeyValue, error)
DelVersionKV([]byte, int64) ([]*types.KeyValue, error)
}
//MVCCHelper impl MVCC interface
type MVCCHelper struct {
*SimpleMVCC
db DB
}
//SimpleMVCC kvdb
type SimpleMVCC struct {
kvdb KVDB
}
var mvcclog = log.New("module", "db.mvcc")
//NewMVCC create MVCC object use db DB
func NewMVCC(db DB) *MVCCHelper {
return &MVCCHelper{SimpleMVCC: NewSimpleMVCC(NewKVDB(db)), db: db}
}
//PrintAll 打印全部
func (m *MVCCHelper) PrintAll() {
println("--meta--")
it := m.db.Iterator(mvccMeta, nil, true)
defer it.Close()
for it.Rewind(); it.Valid(); it.Next() {
if it.Error() != nil {
mvcclog.Error("PrintAll", "error", it.Error())
return
}
println(string(it.Key()), string(it.Value()))
}
println("--data--")
it = m.db.Iterator(mvccData, nil, true)
defer it.Close()
for it.Rewind(); it.Valid(); it.Next() {
if it.Error() != nil {
mvcclog.Error("PrintAll", "error", it.Error())
return
}
println(string(it.Key()), string(it.Value()))
}
println("--last--")
it = m.db.Iterator(mvccLast, nil, true)
defer it.Close()
for it.Rewind(); it.Valid(); it.Next() {
if it.Error() != nil {
mvcclog.Error("PrintAll", "error", it.Error())
return
}
println(string(it.Key()), string(it.Value()))
}
}
//Trash del some old kv
func (m *MVCCHelper) Trash(version int64) error {
it := m.db.Iterator(mvccData, nil, true)
defer it.Close()
perfixkey := []byte("--.xxx.--")
for it.Rewind(); it.Valid(); it.Next() {
if it.Error() != nil {
mvcclog.Error("Trash", "error", it.Error())
return it.Error()
}
//如果进入一个新的key, 这个key 忽略,不删除,也就是至少保留一个
if !bytes.HasPrefix(it.Key(), perfixkey) {
perfixkey = cutVersion(it.Key())
if perfixkey == nil {
perfixkey = []byte("--.xxx.--")
}
continue
}
//第二个key
v, err := getVersion(it.Key())
if err != nil {
mvcclog.Error("Trash get verson", "err", err)
continue
}
if v <= version {
err := m.db.Delete(it.Key())
if err != nil {
mvcclog.Error("Trash Delete verson", "err", err)
}
}
}
return nil
}
//DelVersion del stateHash version map
func (m *MVCCHelper) DelVersion(hash []byte) error {
version, err := m.GetVersion(hash)
if err != nil {
return err
}
kvs, err := m.DelVersionKV(hash, version)
if err != nil {
return err
}
batch := m.db.NewBatch(true)
for _, v := range kvs {
batch.Delete(v.Key)
}
return batch.Write()
}
//SetVersion set stateHash -> version map
func (m *MVCCHelper) SetVersion(hash []byte, version int64) error {
kvlist, err := m.SetVersionKV(hash, version)
if err != nil {
return err
}
batch := m.db.NewBatch(true)
for _, v := range kvlist {
batch.Set(v.Key, v.Value)
}
return batch.Write()
}
//DelV del key with version
func (m *MVCCHelper) DelV(key []byte, version int64) error {
kv, err := m.GetDelKV(key, version)
if err != nil {
return err
}
return m.db.Delete(kv.Key)
}
//NewSimpleMVCC new
func NewSimpleMVCC(db KVDB) *SimpleMVCC {
return &SimpleMVCC{db}
}
//GetVersion get stateHash and version map
func (m *SimpleMVCC) GetVersion(hash []byte) (int64, error) {
key := getVersionHashKey(hash)
value, err := m.kvdb.Get(key)
if err != nil {
if err == ErrNotFoundInDb {
return 0, types.ErrNotFound
}
return 0, err
}
var data types.Int64
err = types.Decode(value, &data)
if err != nil {
return 0, err
}
if data.GetData() < 0 {
return 0, types.ErrVersion
}
return data.GetData(), nil
}
//GetVersionHash 获取版本hash
func (m *SimpleMVCC) GetVersionHash(version int64) ([]byte, error) {
key := getVersionKey(version)
value, err := m.kvdb.Get(key)
if err != nil {
if err == ErrNotFoundInDb {
return nil, types.ErrNotFound
}
return nil, err
}
return value, nil
}
//GetMaxVersion 获取最高版本
func (m *SimpleMVCC) GetMaxVersion() (int64, error) {
vals, err := m.kvdb.List(mvccMetaVersion, nil, 1, ListDESC)
if err != nil {
return 0, err
}
hash := vals[0]
return m.GetVersion(hash)
}
//GetSaveKV only export set key and value with version
func (m *SimpleMVCC) GetSaveKV(key []byte, value []byte, version int64) (*types.KeyValue, error) {
k, err := GetKey(key, version)
if err != nil {
return nil, err
}
return &types.KeyValue{Key: k, Value: value}, nil
}
//GetDelKV only export del key and value with version
func (m *SimpleMVCC) GetDelKV(key []byte, version int64) (*types.KeyValue, error) {
k, err := GetKey(key, version)
if err != nil {
return nil, err
}
return &types.KeyValue{Key: k}, nil
}
//GetDelKVList 获取列表
func (m *SimpleMVCC) GetDelKVList(version int64) ([]*types.KeyValue, error) {
k := getVersionKeyListKey(version)
data, err := m.kvdb.Get(k)
if err != nil {
return nil, err
}
var kvlist types.LocalDBSet
err = types.Decode(data, &kvlist)
if err != nil {
return nil, err
}
return kvlist.KV, nil
}
//SetVersionKV only export SetVersionKV key and value
func (m *SimpleMVCC) SetVersionKV(hash []byte, version int64) ([]*types.KeyValue, error) {
if version < 0 {
return nil, types.ErrVersion
}
key := append(mvccMeta, hash...)
data := &types.Int64{Data: version}
v1 := &types.KeyValue{Key: key, Value: types.Encode(data)}
k2 := append(mvccMetaVersion, pad(version)...)
v2 := &types.KeyValue{Key: k2, Value: hash}
return []*types.KeyValue{v1, v2}, nil
}
//DelVersionKV only export del version key value
func (m *SimpleMVCC) DelVersionKV(hash []byte, version int64) ([]*types.KeyValue, error) {
kvs, err := m.SetVersionKV(hash, version)
if err != nil {
return nil, err
}
for i := 0; i < len(kvs); i++ {
kvs[i].Value = nil
}
return kvs, nil
}
//SetV set key and value with version
func (m *SimpleMVCC) SetV(key []byte, value []byte, version int64) error {
kv, err := m.GetSaveKV(key, value, version)
if err != nil {
return err
}
return m.kvdb.Set(kv.Key, kv.Value)
}
//GetV get key with version
func (m *SimpleMVCC) GetV(key []byte, version int64) ([]byte, error) {
prefix := GetKeyPerfix(key)
search, err := GetKey(key, version)
if err != nil {
return nil, err
}
vals, err := m.kvdb.List(prefix, search, 1, ListSeek)
if err != nil {
return nil, err
}
k := vals[0]
val := vals[1]
v, err := getVersion(k)
if err != nil {
return nil, err
}
if v > version {
return nil, types.ErrVersion
}
return val, nil
}
//AddMVCC add keys in a version
//添加MVCC的规则:
//必须提供现有hash 和 prev 的hash, 而且这两个版本号相差1
func (m *SimpleMVCC) AddMVCC(kvs []*types.KeyValue, hash []byte, prevHash []byte, version int64) ([]*types.KeyValue, error) {
if version > 0 {
if prevHash == nil {
return nil, types.ErrPrevVersion
}
prevVersion := version - 1
vhash, err := m.GetVersionHash(prevVersion)
if err != nil {
return nil, err
}
if !bytes.Equal(vhash, prevHash) {
return nil, types.ErrPrevVersion
}
}
versionlist, err := m.SetVersionKV(hash, version)
if err != nil {
return nil, err
}
var kvlist []*types.KeyValue
kvlist = append(kvlist, versionlist...)
delkeys := &types.LocalDBSet{}
for i := 0; i < len(kvs); i++ {
//最原始的数据
delkeys.KV = append(delkeys.KV, &types.KeyValue{Key: kvs[i].Key})
kv, err := m.GetSaveKV(kvs[i].Key, kvs[i].Value, version)
if err != nil {
return nil, err
}
kvlist = append(kvlist, kv)
}
kvlist = append(kvlist, &types.KeyValue{Key: getVersionKeyListKey(version), Value: types.Encode(delkeys)})
return kvlist, nil
}
//DelMVCC 删除某个版本
//我们目前规定删除的方法:
//1 -> 1-2-3-4-5,6 version 必须连续的增长
//2 -> del 也必须从尾部开始删除
func (m *SimpleMVCC) DelMVCC(hash []byte, version int64, strict bool) ([]*types.KeyValue, error) {
kvs, err := m.GetDelKVList(version)
if err != nil {
return nil, err
}
return m.delMVCC(kvs, hash, version, strict)
}
func (m *SimpleMVCC) delMVCC(kvs []*types.KeyValue, hash []byte, version int64, strict bool) ([]*types.KeyValue, error) {
if strict {
maxv, err := m.GetMaxVersion()
if err != nil {
return nil, err
}
if maxv != version {
return nil, types.ErrCanOnlyDelTopVersion
}
}
//check hash and version is match
vdb, err := m.GetVersion(hash)
if err != nil {
return nil, err
}
if vdb != version {
return nil, types.ErrVersion
}
kv, err := m.DelVersionKV(hash, version)
if err != nil {
return nil, err
}
var kvlist []*types.KeyValue
kvlist = append(kvlist, kv...)
for _, v := range kvs {
kv, err := m.GetDelKV(v.Key, version)
if err != nil {
return nil, err
}
kvlist = append(kvlist, kv)
}
return kvlist, nil
}
func getVersionString(key []byte) (string, error) {
for i := len(key) - 1; i >= 0; i-- {
if key[i] == '.' {
return string(key[i+1:]), nil
}
}
return "", types.ErrVersion
}
func cutVersion(key []byte) []byte {
for i := len(key) - 1; i >= 0; i-- {
if key[i] == '.' {
d := make([]byte, i)
copy(d, key[0:i+1])
return d
}
}
return nil
}
func getVersion(key []byte) (int64, error) {
s, err := getVersionString(key)
if err != nil {
return 0, err
}
return strconv.ParseInt(s, 10, 64)
}
func pad(version int64) []byte {
//equals to `[]byte(fmt.Sprintf("%020d", version))`
sInt := strconv.FormatInt(version, 10)
result := []byte("00000000000000000000")
copy(result[20-len(sInt):], sInt)
return result
}
//GetKeyPerfix 获取key前缀
func GetKeyPerfix(key []byte) []byte {
result := make([]byte, 0, len(mvccData)+len(key)+1)
result = append(result, mvccData...)
result = append(result, key...)
result = append(result, []byte(".")...)
return result
}
//GetKey 获取键
func GetKey(key []byte, version int64) ([]byte, error) {
result := make([]byte, 0, len(mvccData)+len(key)+21)
result = append(result, mvccData...)
result = append(result, key...)
result = append(result, []byte(".")...)
result = append(result, pad(version)...)
return result, nil
}
func getLastKey(key []byte) []byte {
result := make([]byte, 0, len(mvccLast)+len(key))
result = append(result, mvccLast...)
result = append(result, key...)
return result
}
func getVersionHashKey(hash []byte) []byte {
result := make([]byte, 0, len(mvccMeta)+len(hash))
result = append(result, mvccMeta...)
result = append(result, hash...)
return result
}
func getVersionKey(version int64) []byte {
result := make([]byte, 0, len(mvccMetaVersion)+20)
result = append(result, mvccMetaVersion...)
result = append(result, pad(version)...)
return result
}
func getVersionKeyListKey(version int64) []byte {
result := make([]byte, 0, len(mvccMetaVersionKeyList)+20)
result = append(result, mvccMetaVersionKeyList...)
result = append(result, pad(version)...)
return result
}