badger.go

package main

import (
	"fmt"
	"sync"

	"github.com/dgraph-io/badger/badger"
)

func main() {
	opts := badger.DefaultOptions
	opts.Dir = "./data"
	opts.ValueDir = "./data"
	kv, err := badger.NewKV(&opts)
	if err != nil {
		panic(err)
	}

	defer kv.Close()

	wg := new(sync.WaitGroup)
	wg.Add(2)

	go write(kv, wg, 1)
	go write(kv, wg, 2)

	wg.Wait()

	var item badger.KVItem
	err = kv.Get([]byte("test"), &item)
	if err != nil {
		panic(err)
	}

	fmt.Println("Final value:", item.Value())
}

func write(kv *badger.KV, wg *sync.WaitGroup, value byte) {
	defer wg.Done()

	var item badger.KVItem
	err := kv.Get([]byte("test"), &item)
	if err != nil {
		panic(err)
	}

	fmt.Println("Item's value:", item.Value())

	newValue := make([]byte, len(item.Value())+1)
	copy(newValue, item.Value())
	newValue[len(newValue)-1] = value

	fmt.Println("New value:", newValue)
	fmt.Println("Write result:", kv.CompareAndSet([]byte("test"), newValue, item.Counter()))
}