kv_storage.go

package storage

//kv 存储引擎实现

import (

    "github.com/cznic/kv"

    "io"

)

//kv 存储结构体 并且实现了storage存储接口

type kvStorage struct {

    db *kv.DB

}

//打开存储引擎   即：引擎map集合对应的value 值  函数的实现  key为path

//返回存储引擎接口  和  err  代表文件打开错误

func openKVStorage(path string) (Storage, error) {

    options := &kv.Options{}

    db, errOpen := kv.Open(path, options)

    if errOpen != nil {

        var errCreate error

        db, errCreate = kv.Create(path, options)

        if errCreate != nil {

            return &kvStorage{db}, errCreate

        }

    }

    return &kvStorage{db}, nil

}

func (s *kvStorage) WALName() string {

    return s.db.WALName()

}

func (s *kvStorage) Set(k []byte, v []byte) error {

    return s.db.Set(k, v)

}

func (s *kvStorage) Get(k []byte) ([]byte, error) {

    return s.db.Get(nil, k)

}

func (s *kvStorage) Delete(k []byte) error {

    return s.db.Delete(k)

}

func (s *kvStorage) ForEach(fn func(k, v []byte) error) error {

    iter, err := s.db.SeekFirst()

    if err == io.EOF {

        return nil

    } else if err != nil {

        return err

    }

    for {

        key, value, err := iter.Next()

        if err == io.EOF {

            break

        } else if err != nil {

            return err

        }

        if err := fn(key, value); err != nil {

            return err

        }

    }

    return nil

}

func (s *kvStorage) Close() error {

    return s.db.Close()

}