From 47bd07057a55f617f2ad7d5a1cb0128c6df5fbfa Mon Sep 17 00:00:00 2001
From: Meutel <meutel@meutel.net>
Date: Sun, 9 Jul 2017 16:50:55 +0200
Subject: [PATCH] TCP redis like

---
 .gitignore                 |   1 +
 example-redis/main.go      | 116 +++++++++++++++++++++++++++++++++++++
 example-redis/main_test.go |  88 ++++++++++++++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100644 example-redis/main.go
 create mode 100644 example-redis/main_test.go

diff --git a/.gitignore b/.gitignore
index 977e020..780174a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -47,3 +47,4 @@ converter-main/converter-main
 tcpclient/tcpclient
 tcpserver/tcpserver
 echoserver/echoserver
+example-redis/example-redis
diff --git a/example-redis/main.go b/example-redis/main.go
new file mode 100644
index 0000000..56f9aba
--- /dev/null
+++ b/example-redis/main.go
@@ -0,0 +1,116 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"strings"
+)
+
+func getCommand(reader io.Reader) (string, error) {
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		str := scanner.Text()
+		return str, nil
+	}
+	return "", scanner.Err()
+}
+
+func isCommand(str string) bool {
+	switch str {
+	case "GET":
+		fallthrough
+	case "SET":
+		fallthrough
+	case "DEL":
+		return true
+	default:
+		return false
+	}
+}
+
+func parseCmd(line string) (string, string, string, error) {
+	cmd, key, val := "", "", ""
+	var err error
+	parts := strings.Split(line, " ")
+	if len(parts) != 2 && len(parts) != 3 {
+		err = errors.New("Invalid number of arguments")
+	} else {
+		for i, part := range parts {
+			switch i {
+			case 0:
+				if isCommand(part) {
+					cmd = part
+				} else {
+					err = errors.New("Unknown command")
+					break
+				}
+			case 1:
+				key = part
+			case 2:
+				if cmd == "SET" {
+					val = part
+				} else {
+					err = errors.New("Invalid number of arguments")
+				}
+			}
+		}
+	}
+	return cmd, key, val, err
+}
+
+func respond(writer io.Writer, ret string) {
+	_, err := io.WriteString(writer, ret+"\n")
+	if err != nil {
+		log.Println(err)
+	}
+}
+
+func main() {
+	db := make(map[string]string)
+
+	ln, err := net.Listen("tcp", ":9000")
+	if err != nil {
+		panic(err)
+	}
+	defer ln.Close()
+
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			panic(err)
+		}
+
+		go func() {
+			line, err := getCommand(conn)
+			if err != nil {
+				respond(conn, fmt.Sprint(err))
+			}
+			cmd, key, val, err := parseCmd(line)
+			if err != nil {
+				respond(conn, fmt.Sprint(err))
+			}
+			switch cmd {
+			case "DEL":
+				log.Println("Deleting", key)
+				delete(db, key)
+			case "GET":
+				log.Println("Getting", key)
+				ret, ok := db[key]
+				if ok {
+					log.Println("Value found", ret)
+					respond(conn, ret)
+				} else {
+					log.Println("Unknown key", key)
+				}
+			case "SET":
+				log.Println("Setting", key)
+				db[key] = val
+			}
+			defer conn.Close()
+		}()
+	}
+}
diff --git a/example-redis/main_test.go b/example-redis/main_test.go
new file mode 100644
index 0000000..07175bb
--- /dev/null
+++ b/example-redis/main_test.go
@@ -0,0 +1,88 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestGetCommand(t *testing.T) {
+	r := strings.NewReader("test\n")
+	line, err := getCommand(r)
+	if err != nil {
+		t.Log("Should not err")
+		t.Fail()
+	}
+	if line != "test" {
+		t.Log("Invalid command")
+		t.Fail()
+	}
+}
+
+func TestIsCommand(t *testing.T) {
+	tests := map[string]bool{
+		"GET": true,
+		"SET": true,
+		"DEL": true,
+		"XXX": false,
+	}
+	for k, v := range tests {
+		if isCommand(k) != v {
+			t.Log("Error " + k)
+			t.Fail()
+		}
+	}
+}
+
+func TestRespond(t *testing.T) {
+	var bs []byte
+	buf := bytes.NewBuffer(bs)
+	respond(buf, "test")
+	if buf.String() != "test\n" {
+		t.Log("Invalid response (" + buf.String() + ")")
+		t.Fail()
+	}
+}
+
+type ParseCmdTest struct {
+	line  string
+	fails bool
+	cmd   string
+	key   string
+	val   string
+}
+
+func TestParseCommand(t *testing.T) {
+	tests := []ParseCmdTest{
+		{"test", true, "", "", ""},
+		{"test test", true, "", "", ""},
+		{"SET 1 2 3", true, "", "", ""},
+		{"GET 1 2", true, "", "", ""},
+	}
+	for _, test := range tests {
+		c, k, v, e := parseCmd(test.line)
+		if test.fails {
+			if e == nil {
+				t.Log("should fail (" + test.line + ")")
+				t.Fail()
+			}
+		} else {
+			if e != nil {
+				t.Log("should no fail", e)
+				t.Fail()
+			}
+			if c != test.cmd {
+				t.Log("Error command", c, test.cmd)
+				t.Fail()
+			}
+			if k != test.key {
+				t.Log("Error key", k, test.key)
+				t.Fail()
+			}
+			if v != test.val {
+				t.Log("Error value", v, test.val)
+				t.Fail()
+			}
+		}
+	}
+}