Golang笔记

golang boltdb tip

bolt 作者提供的思路

Be sure to check errors from `View()` and `Update()`. For example, there's a missing error check in NewList().
It's more efficient to use `binary.BigEndian.PutUint64()` instead of `fmt.Sprintf()` to represent ids. For one thing, it's much faster to encode & decode. Second of all, when you use a stringified representation then it won't insert sequentially.

官方的一个栗子:

// CreateUser saves u to the store. The new user ID is set on u once the data is persisted.
func (s *Store) CreateUser(u *User) error {
    return s.db.Update(func(tx *bolt.Tx) error {
        // Retrieve the users bucket.
        // This should be created when the DB is first opened.
        b := tx.Bucket([]byte("users"))

        // Generate ID for the user.
        // This returns an error only if the Tx is closed or not writeable.
        // That can't happen in an Update() call so I ignore the error check.
        id, _ := b.NextSequence()
        u.ID = int(id)

        // Marshal user data into bytes.
        buf, err := json.Marshal(u)
        if err != nil {
            return err
        }

        // Persist bytes to users bucket.
        return b.Put(itob(u.ID), buf)
    })
}

// itob returns an 8-byte big endian representation of v.
func itob(v int) []byte {
    b := make([]byte, 8)
    binary.BigEndian.PutUint64(b, uint64(v))
    return b
}

type User struct {
    ID int
    ...
}

byte to int 相互转换:

func Btoi(b []byte) int {
	s0, _ := strconv.Atoi(string(b))
	return s0
}

func Itob(i int) []byte {
	return []byte(strconv.Itoa(i))
}

另外一个,使用字节

func itob(v int64) []byte {
	b := make([]byte, 8)
	binary.BigEndian.PutUint64(b, uint64(v))
	return b
}

func btoi(v []byte) int64 {
	return int64(binary.BigEndian.Uint64(v))
}

时间戳还原:

timestamp := time.Unix(int64(binary.BigEndian.Uint64(v)), 0)
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