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db_badger.go
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db_badger.go
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//
// db_badger.go
// Copyright (C) 2018 YanMing <yming0221@gmail.com>
//
// Distributed under terms of the MIT license.
//
package store
import (
"log"
"os"
"github.com/dgraph-io/badger"
)
type BadgerDB struct {
dir string
valueDir string
db *badger.DB
logger *log.Logger
}
type KVItem struct {
key []byte
value []byte
err error
}
func (i *KVItem) IsFinished() bool {
return i.err == ErrIterFinished
}
func NewBadgerDB(dir, valueDir string) (*BadgerDB, error) {
opts := badger.DefaultOptions
opts.Dir = dir
opts.ValueDir = valueDir
opts.SyncWrites = false
db, err := badger.Open(opts)
if err != nil {
return nil, err
}
return &BadgerDB{
dir: dir,
valueDir: valueDir,
db: db,
logger: log.New(os.Stderr, "[db_badger] ", log.LstdFlags),
}, nil
}
func (b *BadgerDB) Get(key []byte) ([]byte, error) {
value := []byte{}
err := b.db.View(func(txn *badger.Txn) error {
item, err := txn.Get(key)
if err != nil {
if err == badger.ErrKeyNotFound {
return nil
}
return err
}
v, err := item.Value()
if err != nil {
return err
}
value = append([]byte{}, v...)
return nil
})
if err != nil {
return nil, err
} else {
return value, nil
}
}
func (b *BadgerDB) Set(key, value []byte) error {
err := b.db.Update(func(txn *badger.Txn) error {
if err1 := txn.Set(key, value); err1 != nil {
return err1
}
return nil
})
return err
}
func (b *BadgerDB) Delete(key []byte) (bool, error) {
err := b.db.Update(func(txn *badger.Txn) error {
if err1 := txn.Delete(key); err1 != nil {
return err1
}
return nil
})
if err != nil {
return false, err
}
return true, nil
}
func (b *BadgerDB) SnapshotItems() <-chan DataItem {
// create a new channel
ch := make(chan DataItem, 1024)
// generate items from snapshot to channel
go b.db.View(func(txn *badger.Txn) error {
opts := badger.DefaultIteratorOptions
opts.PrefetchSize = 10
it := txn.NewIterator(opts)
defer it.Close()
keyCount := 0
for it.Rewind(); it.Valid(); it.Next() {
item := it.Item()
k := item.Key()
v, err := item.Value()
kvi := &KVItem{
key: append([]byte{}, k...),
value: append([]byte{}, v...),
err: err,
}
// write kvitem to channel with last error
ch <- kvi
keyCount = keyCount + 1
if err != nil {
return err
}
}
// just use nil kvitem to mark the end
kvi := &KVItem{
key: nil,
value: nil,
err: ErrIterFinished,
}
ch <- kvi
b.logger.Printf("Snapshot total %d keys", keyCount)
return nil
})
// return channel to persist
return ch
}
func (b *BadgerDB) Close() {
b.db.Close()
}