store_leveldb.go

package main

import (
	"fmt"

	"github.com/syndtr/goleveldb/leveldb"
)

var _ Store = &LevelDB{}

type LevelDB struct {
	db *leveldb.DB
}

func NewLevelDB(path string) (*LevelDB, error) {
	db, err := leveldb.OpenFile(path, nil)
	return &LevelDB{db}, err
}

func (store *LevelDB) Close() error {
	return store.db.Close()
}

func (store *LevelDB) Get(txhash Hash) ([]byte, error) {
	data, err := store.db.Get(txhash[:], nil)
	if err == leveldb.ErrNotFound {
		err = ErrNotFound
	}
	return data, err
}

func (store *LevelDB) List(fn func(Hash, []byte) error) error {
	iter := store.db.NewIterator(nil, nil)
	defer iter.Release()
	for iter.Next() {
		key, value := iter.Key(), iter.Value()

		var txhash Hash
		if n := copy(txhash[:], key); n != HashLength {
			return ErrInvalidHash
		}

		if err := fn(txhash, value); err != nil {
			return err
		}
	}
	return iter.Error()
}

func (store *LevelDB) Put(txhash Hash, data []byte) error {
	tx, err := store.db.OpenTransaction()
	if err != nil {
		return fmt.Errorf("Problem starting DB transaction: %v", err)
	}
	defer tx.Discard()

	_, err = tx.Get(txhash[:], nil)
	if err == nil {
		return ErrExists
	} else if err != leveldb.ErrNotFound {
		return err
	}

	if err := tx.Put(txhash[:], data, nil); err != nil {
		return err
	}

	return tx.Commit()
}