diff --git a/Dockerfile b/Dockerfile
index 160f514..c4055e3 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,9 +10,14 @@ ARG BUILD_TIME
 
 WORKDIR /build
 
+# 挂载本地缓存加速
+VOLUME ["/go/pkg/mod", "/go/cache"]
+
 COPY . .
 
-RUN go build -ldflags="-s -w -X main.buildTime=${BUILD_TIME}" -o rotom .
+RUN --mount=type=cache,target=/go/pkg/mod \
+    --mount=type=cache,target=/root/.cache/go-build \
+    go build -ldflags="-s -w -X main.buildTime=${BUILD_TIME}" -o rotom .
 
 FROM alpine:latest
 
diff --git a/command.go b/command.go
index 5979e8b..473eafb 100644
--- a/command.go
+++ b/command.go
@@ -3,7 +3,6 @@ package main
 import (
 	"fmt"
 	"github.com/xgzlucario/rotom/internal/resp"
-	"github.com/xgzlucario/rotom/internal/timer"
 	"strconv"
 	"strings"
 	"time"
@@ -64,6 +63,7 @@ var cmdTable = []*Command{
 	{"zrange", zrangeCommand, 3, false},
 	{"eval", evalCommand, 2, true},
 	{"ping", pingCommand, 0, false},
+	{"hello", helloCommand, 0, false},
 	{"flushdb", flushdbCommand, 0, true},
 	{"load", loadCommand, 0, false},
 	{"save", saveCommand, 0, false},
@@ -110,7 +110,7 @@ func setCommand(writer *resp.Writer, args []resp.RESP) {
 				writer.WriteError(errParseInteger)
 				return
 			}
-			ttl = timer.GetNanoTime() + int64(n*time.Second)
+			ttl = time.Now().Add(n * time.Second).UnixNano()
 			extra = extra[2:]
 
 			// PX
@@ -120,7 +120,7 @@ func setCommand(writer *resp.Writer, args []resp.RESP) {
 				writer.WriteError(errParseInteger)
 				return
 			}
-			ttl = timer.GetNanoTime() + int64(n*time.Millisecond)
+			ttl = time.Now().Add(n * time.Millisecond).UnixNano()
 			extra = extra[2:]
 
 			// KEEPTTL
@@ -551,6 +551,39 @@ func flushdbCommand(writer *resp.Writer, _ []resp.RESP) {
 	writer.WriteSString("OK")
 }
 
+func helloCommand(writer *resp.Writer, args []resp.RESP) {
+	var protoVersion int
+	var err error
+
+	if len(args) > 0 {
+		protoVersion, err = args[0].ToInt()
+		if err != nil {
+			writer.WriteError(err)
+			return
+		}
+	}
+
+	result := map[string]any{
+		"server":  "rotom",
+		"version": "1.0.0",
+		"proto":   protoVersion,
+	}
+	if protoVersion == 3 {
+		writer.WriteMapHead(len(result))
+	} else {
+		writer.WriteMapHead(len(result))
+	}
+	for k, v := range result {
+		writer.WriteBulkString(k)
+		switch val := v.(type) {
+		case string:
+			writer.WriteBulkString(val)
+		case int:
+			writer.WriteInteger(val)
+		}
+	}
+}
+
 func loadCommand(writer *resp.Writer, _ []resp.RESP) {
 	db.dict = New()
 	if err := db.rdb.LoadDB(); err != nil {
diff --git a/dict.go b/dict.go
index 337dab4..2cffed5 100644
--- a/dict.go
+++ b/dict.go
@@ -2,7 +2,6 @@ package main
 
 import (
 	"github.com/cockroachdb/swiss"
-	"github.com/xgzlucario/rotom/internal/timer"
 	"time"
 )
 
@@ -12,10 +11,6 @@ type Dict struct {
 	expire *swiss.Map[string, int64]
 }
 
-func init() {
-	timer.Init()
-}
-
 func New() *Dict {
 	return &Dict{
 		data:   swiss.New[string, any](64),
@@ -36,7 +31,7 @@ func (dict *Dict) Get(key string) (any, int) {
 	}
 
 	// key expired
-	now := timer.GetNanoTime()
+	now := time.Now().UnixNano()
 	if ts < now {
 		dict.delete(key)
 		return nil, KEY_NOT_EXIST
@@ -82,7 +77,7 @@ func (dict *Dict) SetTTL(key string, ttl int64) int {
 
 	// check key if already expired
 	ts, ok := dict.expire.Get(key)
-	if ok && ts < timer.GetNanoTime() {
+	if ok && ts < time.Now().UnixNano() {
 		dict.delete(key)
 		return 0
 	}
@@ -94,8 +89,9 @@ func (dict *Dict) SetTTL(key string, ttl int64) int {
 
 func (dict *Dict) EvictExpired() {
 	var count int
+	now := time.Now().UnixNano()
 	dict.expire.All(func(key string, ts int64) bool {
-		if timer.GetNanoTime() > ts {
+		if now > ts {
 			dict.Delete(key)
 		}
 		count++
diff --git a/internal/resp/resp.go b/internal/resp/resp.go
index 9a33279..e0040c3 100644
--- a/internal/resp/resp.go
+++ b/internal/resp/resp.go
@@ -16,7 +16,7 @@ const (
 	INTEGER = ':'
 	BULK    = '$'
 	ARRAY   = '*'
-	MAP     = '%' // TODO: https://redis.io/docs/latest/develop/reference/protocol-spec/#maps
+	MAP     = '%'
 )
 
 var (
@@ -161,6 +161,12 @@ func (w *Writer) WriteArrayHead(n int) {
 	w.b = append(w.b, CRLF...)
 }
 
+func (w *Writer) WriteMapHead(n int) {
+	w.b = append(w.b, MAP)
+	w.b = strconv.AppendUint(w.b, uint64(n), 10)
+	w.b = append(w.b, CRLF...)
+}
+
 // WriteBulk writes a RESP bulk string from a byte slice.
 func (w *Writer) WriteBulk(bulk []byte) {
 	w.WriteBulkString(b2s(bulk))
diff --git a/internal/timer/timer.go b/internal/timer/timer.go
deleted file mode 100644
index 91fad75..0000000
--- a/internal/timer/timer.go
+++ /dev/null
@@ -1,23 +0,0 @@
-package timer
-
-import (
-	"sync/atomic"
-	"time"
-)
-
-var (
-	nanotime atomic.Int64
-)
-
-func Init() {
-	go func() {
-		tk := time.NewTicker(time.Millisecond / 10)
-		for t := range tk.C {
-			nanotime.Store(t.UnixNano())
-		}
-	}()
-}
-
-func GetNanoTime() int64 {
-	return nanotime.Load()
-}