slowpoke

Description

Package slowpoke is a simple key/value store written using Go's standard library only. Keys are stored in memory (with persistence), values stored on disk.

Description on russian: https://habr.com/post/354224/

Motivation

Replace Bolt with a simpler and more efficient engine.

Slowpoke (from version 2.0) based on pudge

How it works

Keys are stored in memory with persistence to disk. Values stored on disk only.

Slowpoke is parallel

Server

GRPC Server example: okdb

Complex examples

typegram

zen platform for authors and their subscribers with a minimalistic design and user-friendly interface.

golang-gin-realworld-example-app

This codebase was created to demonstrate a fully fledged fullstack application built with Golang/Gin/Slowpoke including CRUD operations, authentication, routing, pagination, and more.

Basic example

package main

import (
	"fmt"

	"github.com/recoilme/slowpoke"
)

func main() {
	// create database
	file := "test/example.db"
	// close all opened database
	defer slowpoke.CloseAll()
	// init key/val
	key := []byte("foo")
	val := []byte("bar")
	//store
	slowpoke.Set(file, key, val)
	// get
	res, _ := slowpoke.Get(file, key)
	//result
	fmt.Println(string(res))
}

Lazy example

func TestGob(t *testing.T) {
	file := "test/gob.db"
	DeleteFile(file)
	defer CloseAll()
	type Post struct {
		Id       int
		Content  string
		Category string
	}

	for i := 0; i < 20; i++ {
		post := &Post{Id: i, Content: "Content:" + strconv.Itoa(i)}
		err := SetGob(file, post.Id, post)
		ch(err, t)
	}

	for i := 0; i < 20; i++ {
		var post = new(Post)
		err := GetGob(file, i, post)
		ch(err, t)
		fmt.Println("i:", i, "Post:", post)
	}
}

Advanced example

type Post struct {
	Id       int
	Content  string
	Category string
}

func main() {
	posts := "test/posts"
	tags := "test/tags"
	var pairs [][]byte
	for i := 0; i < 40; i++ {
		id := make([]byte, 4)
		binary.BigEndian.PutUint32(id, uint32(i))
		post := &Post{Id: i, Content: "Content:" + strconv.Itoa(i), Category: "Category:" + strconv.Itoa(i/10)}
		b, _ := json.Marshal(post)
		pairs = append(pairs, id)
		pairs = append(pairs, b)
		tag := fmt.Sprintf("%s:%08d", strconv.Itoa(i/10), i)
		//store only tags keys
		slowpoke.Set(tags, []byte(tag), nil)
	}
	//store posts fast
	slowpoke.Sets(posts, pairs)

	//get last 2 post key with offset 2
	limit := uint32(2)
	offset := uint32(2)
	order := false //desc
	keys, _ := slowpoke.Keys(posts, nil, limit, offset, order)
	fmt.Println(keys) //[[0 0 0 37] [0 0 0 36]]

	//get key/ values
	res := slowpoke.Gets(posts, keys)
	for k, v := range res {
		if k%2 == 0 {
			fmt.Print(binary.BigEndian.Uint32(v))
		} else {
			var p Post
			json.Unmarshal(v, &p)
			fmt.Println(p)
		}
	}
	//37{37 Content:37 Category:3}
	//36{36 Content:36 Category:3}

	//free from memory
	slowpoke.Close(posts)
	slowpoke.Close(tags)

	//open Db and read tags by prefix 2:* in ascending order
	tagsKeys, _ := slowpoke.Keys(tags, []byte("2:*"), 0, 0, true)
	for _, v := range tagsKeys {
		fmt.Print(string(v) + ", ")
	}
	//2:00000020, 2:00000021, 2:00000022, 2:00000023, 2:00000024, 2:00000025, 2:00000026, 2:00000027, 2:00000028, 2:00000029,
}

Api

All methods are thread-safe.

• Set/Sets/SetGob

Store val and key. If the file does not exist it will be created.

• Get/Gets/GetGob

Return the value for the given key or nil and an error. Get will open the database if necessary.

• Keys

Return keys in ascending/descending order.

With limit and offset.

If from is not nil, return keys lexicographically greater than the from value.

If from ends with asterix *, return keys with the prefix equal to from without the asterix.

Documentation

Status

Used in production (master branch)

Benchmark

All tests here

Some tests, MacBook Pro (Retina, 13-inch, Early 2015)

Test 1

Number of keys: 1000000
Minimum key size: 16, maximum key size: 64
Minimum value size: 128, maximum value size: 512
Concurrency: 2