dione/blockchain/utils/index.go

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2021-06-04 21:18:06 +00:00
package utils
import (
"encoding/binary"
"encoding/hex"
"fmt"
"github.com/ledgerwatch/lmdb-go/lmdb"
)
const (
DefaultIndexPrefix = "indexes/"
)
var (
ErrIndexKeyNotFound = fmt.Errorf("key is not found in the index")
)
type Index struct {
name string
dbEnv *lmdb.Env
db lmdb.DBI
}
func NewIndex(name string, dbEnv *lmdb.Env, db lmdb.DBI) *Index {
return &Index{
name: name,
db: db,
dbEnv: dbEnv,
}
}
func (i *Index) PutUint64(key []byte, value uint64) error {
return i.dbEnv.Update(func(txn *lmdb.Txn) error {
var data []byte
binary.LittleEndian.PutUint64(data, value)
return txn.Put(i.db, i.constructIndexKey(key), data, 0)
})
}
func (i *Index) GetUint64(key []byte) (uint64, error) {
var num uint64
err := i.dbEnv.View(func(txn *lmdb.Txn) error {
data, err := txn.Get(i.db, i.constructIndexKey(key))
if err != nil {
if lmdb.IsNotFound(err) {
return ErrIndexKeyNotFound
}
return err
}
num = binary.LittleEndian.Uint64(data)
return nil
})
if err != nil {
return 0, err
}
return num, nil
}
func (i *Index) PutBytes(key []byte, value []byte) error {
return i.dbEnv.Update(func(txn *lmdb.Txn) error {
return txn.Put(i.db, i.constructIndexKey(key), value, 0)
})
}
func (i *Index) GetBytes(key []byte) ([]byte, error) {
var data []byte
err := i.dbEnv.View(func(txn *lmdb.Txn) error {
valueData, err := txn.Get(i.db, i.constructIndexKey(key))
if err != nil {
if lmdb.IsNotFound(err) {
return ErrIndexKeyNotFound
}
return err
}
data = valueData
return nil
})
if err != nil {
return nil, err
}
return data, nil
}
func (i *Index) Delete(key []byte) error {
return i.dbEnv.Update(func(txn *lmdb.Txn) error {
return txn.Del(i.db, i.constructIndexKey(key), nil)
})
}
func (i *Index) constructIndexKey(key []byte) []byte {
k := hex.EncodeToString(key)
return []byte(fmt.Sprintf("%s/%s/%s", DefaultIndexPrefix, i.name, k))
}