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txn.go
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txn.go
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//
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package localstore
import (
"fmt"
"runtime/debug"
"strconv"
"time"
"github.com/juju/errors"
"github.com/ngaut/log"
"github.com/Dong-Chan/alloydb/kv"
"github.com/syndtr/goleveldb/leveldb/iterator"
)
var (
_ kv.Transaction = (*dbTxn)(nil)
// ErrInvalidTxn is the error when commits or rollbacks in an invalid transaction.
ErrInvalidTxn = errors.New("invalid transaction")
// ErrCannotSetNilValue is the error when sets an empty value
ErrCannotSetNilValue = errors.New("can not set nil value")
)
// dbTxn is not thread safe
type dbTxn struct {
kv.UnionStore
store *dbStore // for commit
startTs time.Time
tID int64
opCnt int64
valid bool
snapshotVals map[string][]byte // origin version in snapshot
}
func (txn *dbTxn) markOrigin(k []byte) error {
keystr := string(k)
// Already exist, no nothing
if _, ok := txn.snapshotVals[keystr]; ok {
return nil
}
val, err := txn.Snapshot.Get(k)
if err != nil && !kv.IsErrNotFound(err) {
return err
}
//log.Debugf("markOrigin, key:%s, value:%s", keystr, val)
txn.snapshotVals[keystr] = val
return nil
}
// Implement transaction interface
func (txn *dbTxn) Inc(k []byte, step int64) (int64, error) {
log.Debugf("Inc %s, step %d txn:%d", k, step, txn.tID)
k = kv.EncodeKey(k)
if err := txn.markOrigin(k); err != nil {
return 0, err
}
val, err := txn.UnionStore.Get(k)
if kv.IsErrNotFound(err) {
err = txn.UnionStore.Set(k, []byte(strconv.FormatInt(step, 10)))
if err != nil {
return 0, err
}
return step, nil
}
if err != nil {
return 0, err
}
intVal, err := strconv.ParseInt(string(val), 10, 0)
if err != nil {
return intVal, err
}
intVal += step
err = txn.UnionStore.Set(k, []byte(strconv.FormatInt(intVal, 10)))
if err != nil {
return 0, err
}
return intVal, nil
}
func (txn *dbTxn) String() string {
return fmt.Sprintf("%d", txn.tID)
}
func (txn *dbTxn) Get(k []byte) ([]byte, error) {
log.Debugf("get key:%s, txn:%d", k, txn.tID)
k = kv.EncodeKey(k)
val, err := txn.UnionStore.Get(k)
if kv.IsErrNotFound(err) {
return nil, kv.ErrNotExist
}
if err != nil {
return nil, err
}
if len(val) == 0 {
return nil, kv.ErrNotExist
}
return val, nil
}
func (txn *dbTxn) Set(k []byte, data []byte) error {
if len(data) == 0 {
// Incase someone use it in the wrong way, we can figure it out immediately
debug.PrintStack()
return ErrCannotSetNilValue
}
log.Debugf("set key:%s, txn:%d", k, txn.tID)
k = kv.EncodeKey(k)
return txn.UnionStore.Set(k, data)
}
func (txn *dbTxn) Seek(k []byte, fnKeyCmp func([]byte) bool) (kv.Iterator, error) {
log.Debugf("seek %s txn:%d", k, txn.tID)
k = kv.EncodeKey(k)
iter, err := txn.UnionStore.Seek(k, txn)
if err != nil {
return nil, err
}
if !iter.Valid() {
return &kv.UnionIter{}, nil
}
if fnKeyCmp != nil {
if fnKeyCmp([]byte(iter.Key())[:1]) {
return &kv.UnionIter{}, nil
}
}
return iter, nil
}
func (txn *dbTxn) Delete(k []byte) error {
log.Debugf("delete %s txn:%d", k, txn.tID)
k = kv.EncodeKey(k)
return txn.UnionStore.Delete(k)
}
func (txn *dbTxn) each(f func(iterator.Iterator) error) error {
iter := txn.UnionStore.Dirty.NewIterator(nil)
defer iter.Release()
for iter.Next() {
if err := f(iter); err != nil {
return err
}
}
return nil
}
func (txn *dbTxn) doCommit() error {
b := txn.store.newBatch()
keysLocked := make([]string, 0, len(txn.snapshotVals))
defer func() {
for _, key := range keysLocked {
txn.store.unLockKeys(key)
}
}()
// Check locked keys
for k, v := range txn.snapshotVals {
err := txn.store.tryConditionLockKey(txn.tID, k, v)
if err != nil {
return errors.Trace(err)
}
keysLocked = append(keysLocked, k)
}
// Check dirty store
err := txn.each(func(iter iterator.Iterator) error {
if len(iter.Value()) == 0 { // Deleted marker
b.Delete(iter.Key())
} else {
b.Put(iter.Key(), iter.Value())
}
return nil
})
if err != nil {
return errors.Trace(err)
}
return txn.store.writeBatch(b)
}
func (txn *dbTxn) Commit() error {
if !txn.valid {
return ErrInvalidTxn
}
log.Infof("commit txn %d", txn.tID)
defer func() {
txn.close()
}()
return txn.doCommit()
}
func (txn *dbTxn) close() error {
txn.UnionStore.Close()
txn.snapshotVals = nil
txn.valid = false
return nil
}
func (txn *dbTxn) Rollback() error {
if !txn.valid {
return ErrInvalidTxn
}
log.Warnf("Rollback txn %d", txn.tID)
return txn.close()
}
func (txn *dbTxn) LockKeys(keys ...[]byte) error {
for _, key := range keys {
key = kv.EncodeKey(key)
if err := txn.markOrigin(key); err != nil {
return err
}
}
return nil
}