kvdb/db.go

package kvdb

import "context"

type (

	contextKey struct {}

	Iterator interface {
		Next() bool
		Key() string
		Value() []byte
		Close() error
	}

	DB interface {
		Open() error
		Put(string, []byte) error
		Get(string) ([]byte, error)
		Delete(string) error
		Iterator(string) (Iterator, error)
		Close() error
	}
)

var (
	ctxKey = contextKey{}
)

func WithContext(c context.Context, v DB) context.Context {
	if c == nil {
		c = context.Background()
	}
	return context.WithValue(c, ctxKey, v)
}

func FromContext(c context.Context) DB {
	if c != nil {
		if v := c.Value(ctxKey); v != nil {
			if x, ok := v.(DB); ok {
				return x
			}
		}
	}
	return nil
}