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package nodb
import (
"errors"
"fmt"
"github.com/lunny/nodb/store"
)
var (
ErrNestTx = errors.New("nest transaction not supported")
ErrTxDone = errors.New("Transaction has already been committed or rolled back")
)
type Tx struct {
*DB
tx *store.Tx
logs [][]byte
}
func (db *DB) IsTransaction() bool {
return db.status == DBInTransaction
}
// Begin a transaction, it will block all other write operations before calling Commit or Rollback.
// You must be very careful to prevent long-time transaction.
func (db *DB) Begin() (*Tx, error) {
if db.IsTransaction() {
return nil, ErrNestTx
}
tx := new(Tx)
tx.DB = new(DB)
tx.DB.l = db.l
tx.l.wLock.Lock()
tx.DB.sdb = db.sdb
var err error
tx.tx, err = db.sdb.Begin()
if err != nil {
tx.l.wLock.Unlock()
return nil, err
}
tx.DB.bucket = tx.tx
tx.DB.status = DBInTransaction
tx.DB.index = db.index
tx.DB.kvBatch = tx.newBatch()
tx.DB.listBatch = tx.newBatch()
tx.DB.hashBatch = tx.newBatch()
tx.DB.zsetBatch = tx.newBatch()
tx.DB.binBatch = tx.newBatch()
tx.DB.setBatch = tx.newBatch()
return tx, nil
}
func (tx *Tx) Commit() error {
if tx.tx == nil {
return ErrTxDone
}
tx.l.commitLock.Lock()
err := tx.tx.Commit()
tx.tx = nil
if len(tx.logs) > 0 {
tx.l.binlog.Log(tx.logs...)
}
tx.l.commitLock.Unlock()
tx.l.wLock.Unlock()
tx.DB.bucket = nil
return err
}
func (tx *Tx) Rollback() error {
if tx.tx == nil {
return ErrTxDone
}
err := tx.tx.Rollback()
tx.tx = nil
tx.l.wLock.Unlock()
tx.DB.bucket = nil
return err
}
func (tx *Tx) newBatch() *batch {
return tx.l.newBatch(tx.tx.NewWriteBatch(), &txBatchLocker{}, tx)
}
func (tx *Tx) Select(index int) error {
if index < 0 || index >= int(MaxDBNumber) {
return fmt.Errorf("invalid db index %d", index)
}
tx.DB.index = uint8(index)
return nil
}
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