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package main
import (
"bufio"
"errors"
"fmt"
"net"
"os"
"strings"
"time"
)
const NumShards = 16
var db RedisDB
var hub Hub
type baseHandlerFunc func([]string)interface{}
type connectionHandlerFunc func(net.Conn, []string)
var baseCommandRegistry = map[string]baseHandlerFunc{
"GET": handleGet,
"SET": handleSet,
"DEL": handleDel,
"EXISTS": handleExists,
"INCR": handleIncr,
"DECR": handleDecr,
"RENAME": handleRename,
"FLUSHALL": handleFlushall,
"RPUSH": handleRpush,
"LPUSH": handleLpush,
"LRANGE": handleLrange,
"LPOP": handleLpop,
"RPOP": handleRpop,
"EXPIRE": handleExpire,
"HSET": handleHset,
"HGET": handleHget,
"HGETALL": handleHgetall,
"HKEYS": handleHkeys,
"HVALUES": handleHvalues,
"TYPE": handleType,
"DBSIZE": handleDbsize,
"KEYS": handleKeys,
"LREM": handleLrem,
}
var connectionCommandRegistry = map[string]connectionHandlerFunc{
"SUBSCRIBE": handleSubscribe,
"UNSUBSCRIBE": handleUnsubscribe,
"PUBLISH": handlePublish,
"PING": handlePing,
}
func main() {
shards := make([]*Shard, NumShards)
for i := 0; i < NumShards; i++ {
shards[i] = &Shard{
data: make(map[string]Item),
id: i,
}
}
db = RedisDB{shards: shards}
hub = Hub{Channels: make(map[string]map[net.Conn]struct{}),}
go func() {
ticker := time.NewTicker(1 * time.Second)
for range ticker.C {
for _,shard := range db.shards{
shard.mu.Lock()
for k, v := range shard.data {
if v.ExpiresAt != nil && time.Now().After(*v.ExpiresAt) {
delete(shard.data, k)
}
}
shard.mu.Unlock()
}
}
}()
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 handleConnection(conn net.Conn) {
defer func() {
handleDisconnect(conn)
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])
if handler, ok := baseCommandRegistry[command]; ok {
conn.Write(serializeRESP(handler(args)))
} else {
conn.Write(serializeRESP(errors.New("unknown command")))
}
}
}
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