Testing cache mechanism using gob encoding and Redis. Version 2.

main.go

package main

import (
	"bytes"
	"context"
	"encoding/gob"
	"fmt"
	"os"
	"time"

	"github.com/gomodule/redigo/redis"
)

type User struct {
	Name    string
	Age     int
	Address string
}

func main() {
	r := NewRepository(&redis.Pool{
		DialContext: func(ctx context.Context) (redis.Conn, error) {
			return redis.Dial("tcp", "localhost:6379")
		},

		MaxIdle:     1024,
		IdleTimeout: 5 * time.Minute,
	})

	ctx := context.Background()

	// Save
	userName := os.Args[1]
	u := User{Name: userName, Age: 25, Address: "Tokyo"}
	r.setCache(ctx, fmt.Sprintf("user_%s", userName), u)

	// Reset
	u = User{}

	// Load
	var loadUser User
	r.getCache(ctx, fmt.Sprintf("user_%s", userName), &loadUser)

	fmt.Printf("%+v\n", loadUser)
}

type Repository struct {
	pool *redis.Pool
}

func NewRepository(pool *redis.Pool) *Repository {
	return &Repository{pool: pool}
}

func (r *Repository) getCache(ctx context.Context, key string, v interface{}) error {
	conn, err := r.pool.GetContext(ctx)
	if err != nil {
		return fmt.Errorf("get redis connection: %w", err)
	}
	defer conn.Close()

	bs, err := redis.Bytes(conn.Do("GET", key))
	if err != nil {
		return fmt.Errorf("get bytes: %w", err)
	}

	reader := bytes.NewReader(bs)
	if err := gob.NewDecoder(reader).Decode(v); err != nil {
		return fmt.Errorf("decode gob: %w", err)
	}

	return nil
}

func (r *Repository) setCache(ctx context.Context, key string, v interface{}) error {
	conn, err := r.pool.GetContext(ctx)
	if err != nil {
		return fmt.Errorf("get redis connection: %w", err)
	}
	defer conn.Close()

	var buf bytes.Buffer
	if err := gob.NewEncoder(&buf).Encode(v); err != nil {
		return fmt.Errorf("encode gob: %w", err)
	}

	if _, err := conn.Do("SET", key, buf.Bytes()); err != nil {
		return fmt.Errorf("set bytes: %w", err)
	}

	return nil
}