✨ add external simpleredis and add log for cache (#73)

* ✨ add external simpleredis and add log for cache

* 🐛 fix comment

vendor/github.com/maxlerebourg/simpleredis/simpleredis.go

@@ -0,0 +1,137 @@
+// Package simpleredis implements utility routines for interacting.
+// It supports currently the following operations: GET, SET, DELETE,
+// and support timetoleave for keys.
+package simpleredis
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"net/textproto"
+	"strings"
+	"time"
+)
+
+// Error strings for redis.
+const (
+	RedisUnreachable = "redis:unreachable"
+	RedisMiss        = "redis:miss"
+	RedisTimeout     = "redis:timeout"
+)
+
+// A RedisCmd is used to communicate with redis at low level using commands.
+type RedisCmd struct {
+	Command  string
+	Name     string
+	Data     []byte
+	Duration int64
+	Error    error
+}
+
+// A SimpleRedis is used to communicate with redis.
+type SimpleRedis struct {
+	redisHost string
+}
+
+func genRedisArray(params ...[]byte) []byte {
+	MSG := ""
+	for cntr := 0; cntr < len(params); cntr++ {
+		MSG = strings.Join([]string{MSG, string(params[cntr])}, " ")
+	}
+	MSG = strings.Trim(MSG, " ")
+	MSG = strings.Join([]string{MSG, "\r\n"}, "")
+	return []byte(MSG)
+}
+
+func send(wr *textproto.Writer, method string, data []byte) {
+	if err := wr.PrintfLine(string(data)); err != nil {
+		fmt.Printf("redis:%s  %s", method, err.Error())
+	}
+}
+
+func askRedis(hostnamePort string, cmd RedisCmd, channel chan RedisCmd) {
+	dialer := net.Dialer{Timeout: 2 * time.Second}
+	conn, err := dialer.Dial("tcp", hostnamePort)
+	if err != nil {
+		channel <- RedisCmd{Error: fmt.Errorf(RedisUnreachable)}
+		return
+	}
+	defer func() {
+		if err := conn.Close(); err != nil {
+			fmt.Printf("redis:connClose %s", err.Error())
+		}
+	}()
+
+	writer := textproto.NewWriter(bufio.NewWriter(conn))
+	reader := textproto.NewReader(bufio.NewReader(conn))
+
+	switch cmd.Command {
+	case "SET":
+		data := genRedisArray([]byte("SET"), []byte(cmd.Name), cmd.Data, []byte("EX"), []byte(fmt.Sprintf("%d", cmd.Duration)))
+		send(writer, "set", data)
+	case "DEL":
+		data := genRedisArray([]byte("DEL"), []byte(cmd.Name))
+		send(writer, "del", data)
+	case "GET":
+		data := genRedisArray([]byte("GET"), []byte(cmd.Name))
+		send(writer, "get", data)
+		for {
+			select {
+			case <-time.After(time.Second * 1):
+				channel <- RedisCmd{Error: fmt.Errorf(RedisTimeout)}
+				return
+			default:
+				read, _ := reader.ReadLineBytes()
+				if string(read) != "$1" {
+					channel <- RedisCmd{Error: fmt.Errorf(RedisMiss)}
+					return
+				}
+				read, _ = reader.ReadLineBytes()
+				channel <- RedisCmd{Data: read}
+				return
+			}
+		}
+	}
+}
+
+// Init sets the redisHost used to connect to redis.
+func (sr *SimpleRedis) Init(redisHost string) {
+	sr.redisHost = redisHost
+}
+
+// Get fetches the value for key name in redis.
+func (sr *SimpleRedis) Get(name string) ([]byte, error) {
+	redisCmd := RedisCmd{
+		Command: "GET",
+		Name:    name,
+	}
+	channel := make(chan RedisCmd)
+	go askRedis(sr.redisHost, redisCmd, channel)
+	resp := <-channel
+	if resp.Error != nil {
+		return nil, resp.Error
+	}
+	return resp.Data, nil
+}
+
+// Set updates the value for key name in redis with value data for duration.
+func (sr *SimpleRedis) Set(name string, data []byte, duration int64) error {
+	redisCmd := RedisCmd{
+		Command:  "SET",
+		Name:     name,
+		Data:     data,
+		Duration: duration,
+	}
+	go askRedis(sr.redisHost, redisCmd, nil)
+	return nil
+}
+
+// Del removes the key name in redis.
+func (sr *SimpleRedis) Del(name string) error {
+	redisCmd := RedisCmd{
+		Command: "DEL",
+		Name:    name,
+	}
+	go askRedis(sr.redisHost, redisCmd, nil)
+	return nil
+}