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badgerdb.go
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badgerdb.go
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package badgerdb
import (
"bytes"
"fmt"
"time"
"github.com/dgraph-io/badger"
"github.com/renproject/kv/db"
)
// badgerDB is a badgerDB implementation of the `db.Iterable`.
type badgerDB struct {
db *badger.DB
codec db.Codec
}
// New returns a new `db.Iterable`.
func New(path string, codec db.Codec) db.DB {
if codec == nil {
panic("codec cannot be nil")
}
opts := badger.DefaultOptions(path)
db, err := badger.Open(opts)
if err != nil {
panic(fmt.Sprintf("error initialising badgerdb: %v", err))
}
bdb := &badgerDB{
db: db,
codec: codec,
}
go bdb.gc()
return bdb
}
// Close implements the `db.DB` interface.
func (bdb *badgerDB) Close() error {
return bdb.db.Close()
}
// Insert implements the `db.DB` interface.
func (bdb *badgerDB) Insert(key string, value interface{}) error {
data, err := bdb.codec.Encode(value)
if err != nil {
return err
}
err = bdb.db.Update(func(txn *badger.Txn) error {
return txn.Set([]byte(key), data)
})
return convertErr(err)
}
// Get implements the `db.DB` interface.
func (bdb *badgerDB) Get(key string, value interface{}) error {
if key == "" {
return db.ErrEmptyKey
}
err := bdb.db.View(func(txn *badger.Txn) error {
item, err := txn.Get([]byte(key))
if err != nil {
return err
}
data, err := item.ValueCopy(nil)
if err != nil {
return err
}
return bdb.codec.Decode(data, value)
})
return convertErr(err)
}
// Delete implements the `db.DB` interface.
func (bdb *badgerDB) Delete(key string) error {
if key == "" {
return db.ErrEmptyKey
}
err := bdb.db.Update(func(txn *badger.Txn) error {
return txn.Delete([]byte(key))
})
return convertErr(err)
}
// Size implements the `db.DB` interface.
func (bdb *badgerDB) Size(prefix string) (int, error) {
count := 0
err := bdb.db.View(func(txn *badger.Txn) error {
opts := badger.DefaultIteratorOptions
opts.Prefix = []byte(prefix)
it := txn.NewIterator(opts)
defer it.Close()
for it.Rewind(); it.Valid(); it.Next() {
count++
}
return nil
})
return count, err
}
// Iterator implements the `db.DB` interface.
func (bdb *badgerDB) Iterator(prefix string) db.Iterator {
tx := bdb.db.NewTransaction(false)
opts := badger.DefaultIteratorOptions
opts.Prefix = []byte(prefix)
iter := tx.NewIterator(opts)
iter.Rewind()
return &iterator{
prefix: []byte(prefix),
initialized: false,
tx: tx,
iter: iter,
codec: bdb.codec,
}
}
func (bdb *badgerDB) gc() {
ticker := time.NewTicker(5 * time.Minute)
defer ticker.Stop()
for range ticker.C {
err := bdb.db.RunValueLogGC(0.5)
if err != nil {
return
}
}
}
// iterator implements the `db.Iterator` interface.
type iterator struct {
prefix []byte
initialized bool
tx *badger.Txn
iter *badger.Iterator
codec db.Codec
}
// Next implements the `db.Iterator` interface.
func (iter *iterator) Next() bool {
if !iter.initialized {
iter.initialized = true
} else {
if !iter.iter.Valid() {
return false
}
iter.iter.Next()
}
if valid := iter.iter.Valid(); !valid {
iter.iter.Close()
iter.tx.Discard()
return false
}
return true
}
// Key implements the `db.Iterator` interface.
func (iter *iterator) Key() (string, error) {
if !iter.initialized || !iter.iter.Valid() {
return "", db.ErrIndexOutOfRange
}
key := iter.iter.Item().Key()
return string(bytes.TrimPrefix(key, iter.prefix)), nil
}
// Value implements the `db.Iterator` interface.
func (iter *iterator) Value(value interface{}) error {
if !iter.initialized || !iter.iter.Valid() {
return db.ErrIndexOutOfRange
}
data, err := iter.iter.Item().ValueCopy(nil)
if err != nil {
return err
}
return iter.codec.Decode(data, value)
}
// Close implements the `db.Iterator` interface.
func (iter *iterator) Close() {
iter.iter.Close()
iter.tx.Discard()
}
// convertErr will convert badgerDB-specific error to kv error.
func convertErr(err error) error {
switch err {
case badger.ErrEmptyKey:
return db.ErrEmptyKey
case badger.ErrKeyNotFound:
return db.ErrKeyNotFound
default:
return err
}
}