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|
package main
import (
"bufio"
"fmt"
"io"
"net"
"os"
"strconv"
"strings"
"sync"
)
type RedisDB struct {
mu sync.Mutex
data map[string]any
}
var db RedisDB
func main() {
db = RedisDB{data: make(map[string]any)}
listener, err := net.Listen("tcp", ":6379")
if err != nil {
fmt.Println("error starting server: ", err)
os.Exit(1)
}
defer listener.Close()
fmt.Println("Redis clone listening on port 6379...")
for {
conn, err := listener.Accept()
if err != nil {
fmt.Println("Error accepting connection:", err)
continue
}
go handleConnection(conn)
}
}
func handleGet(conn net.Conn, key string) {
db.mu.Lock()
defer db.mu.Unlock()
value, exists := db.data[key]
if !exists {
conn.Write([]byte("$-1\r\n"))
return
}
strValue, ok := value.(string)
if !ok {
conn.Write([]byte("-WRONGTYPE Operation against a key holding the wrong kind of value\r\n"))
return
}
conn.Write([]byte("+" + strValue + "\r\n"))
}
func handleExists(conn net.Conn, key string) {
db.mu.Lock()
defer db.mu.Unlock()
_, exists := db.data[key]
if exists {
conn.Write([]byte(":1\r\n"))
} else {
conn.Write([]byte(":0\r\n"))
}
}
func handleSet(conn net.Conn, key, value string) {
db.mu.Lock()
defer db.mu.Unlock()
db.data[key] = value
conn.Write([]byte("+OK\r\n"))
}
func handleDel(conn net.Conn, key string) {
db.mu.Lock()
defer db.mu.Unlock()
_, exists := db.data[key]
if exists {
delete(db.data, key)
conn.Write([]byte(":1\r\n"))
} else {
conn.Write([]byte(":0\r\n"))
}
}
func handleIncr(conn net.Conn, key string) {
db.mu.Lock()
defer db.mu.Unlock()
value, exists := db.data[key]
if exists {
strValue, ok := value.(string)
if !ok {
conn.Write([]byte("-ERR value is not an integer or out of range\r\n"))
return
}
currentInt, err := strconv.Atoi(strValue)
if err != nil {
conn.Write([]byte("-ERR value is not an integer or out of range\r\n"))
return
}
newValueStr := strconv.Itoa(currentInt + 1)
db.data[key] = newValueStr
conn.Write([]byte(":" + newValueStr + "\r\n"))
} else {
db.data[key] = "1"
conn.Write([]byte(":1\r\n"))
}
}
func handleDecr(conn net.Conn, key string) {
db.mu.Lock()
defer db.mu.Unlock()
value, exists := db.data[key]
if exists {
strValue, ok := value.(string)
if !ok {
conn.Write([]byte("-ERR value is not an integer or out of range\r\n"))
return
}
currentInt, err := strconv.Atoi(strValue)
if err != nil {
conn.Write([]byte("-ERR value is not an integer or out of range\r\n"))
return
}
newValueStr := strconv.Itoa(currentInt - 1)
db.data[key] = newValueStr
conn.Write([]byte(":" + newValueStr + "\r\n"))
} else {
db.data[key] = "-1"
conn.Write([]byte(":-1\r\n"))
}
}
func handlePing(conn net.Conn) {
conn.Write([]byte("+PONG\r\n"))
}
func handleFlushall(conn net.Conn) {
db.mu.Lock()
defer db.mu.Unlock()
db.data = make(map[string]any)
conn.Write([]byte("+OK\r\n"))
}
func handleRpush(conn net.Conn, args []string) {
key := args[1]
newItems := args[2:]
db.mu.Lock()
defer db.mu.Unlock()
var list []string
existingValue, exists := db.data[key]
if exists {
var ok bool
list, ok = existingValue.([]string)
if !ok {
conn.Write([]byte("-WRONGTYPE Operation against a key holding the wrong kind of value\r\n"))
return
}
} else {
list = []string{}
}
list = append(list, newItems...)
db.data[key] = list
conn.Write([]byte(":" + strconv.Itoa(len(list)) + "\r\n"))
}
func parseRESP(reader *bufio.Reader) ([]string, error) {
line, err := reader.ReadString('\n')
if err != nil {
return nil, err
}
if len(line) == 0 {
return nil, fmt.Errorf("empty line")
}
switch line[0] {
case '*':
var args []string
argC, _ := strconv.Atoi(strings.TrimSpace(line[1:]))
for i := 0; i < argC; i++ {
nestedArgs, err := parseRESP(reader)
if err != nil {
return nil, err
}
args = append(args, nestedArgs...)
}
return args, nil
case '$':
strLen, _ := strconv.Atoi(strings.TrimSpace(line[1:]))
if strLen == -1 {
return []string{""}, nil
}
buf := make([]byte, strLen)
_, err = io.ReadFull(reader, buf)
if err != nil {
return nil, err
}
_, err = reader.Discard(2)
if err != nil {
return nil, err
}
return []string{string(buf)}, nil
case '+':
cleanStr := strings.TrimSpace(line[1:])
return []string{cleanStr}, nil
case ':':
return []string{strings.TrimSpace(line[1:])}, nil
default:
return nil, fmt.Errorf("unknown command type: %c", line[0])
}
}
func handleConnection(conn net.Conn) {
defer conn.Close()
fmt.Println("Client connected:", conn.RemoteAddr())
reader := bufio.NewReader(conn)
for {
args, err := parseRESP(reader)
if err != nil {
fmt.Println("Client disconnected or error parsing:", conn.RemoteAddr(), err)
return
}
if len(args) == 0 {
continue
}
fmt.Printf("Parsed RESP Arguments: %v\n", args)
command := strings.ToUpper(args[0])
switch {
case command == "GET" && len(args) == 2:
handleGet(conn, args[1])
case command == "SET" && len(args) == 3:
handleSet(conn, args[1], args[2])
case command == "EXISTS" && len(args) == 2:
handleExists
|
