feat: add Close() method to RedHub server

Add a Close() method to allow graceful shutdown of the RedHub server.
This addresses issue #14 and provides a similar API to tidwall/redcon.

Changes:
- Add mu, addr, and running fields to RedHub struct for server state
- Add Close() method that gracefully shuts down the server
- Modify ListenAndServe to track server state
- Add unit tests for Close() functionality
- Add integration test for Close() method

The Close() method:
- Returns error if server is not running
- Calls gnet.Stop() to gracefully shutdown
- Is thread-safe with mutex protection
- Can be called from any goroutine

Author: BlockCraftsman

redhub.go

@@ -56,6 +56,8 @@ package redhub
 
 import (
 	"bytes"
+	"context"
+	"errors"
 	"sync"
 	"time"
 
@@ -203,6 +205,10 @@ type RedHub struct {
 	handler      func(cmd resp.Command, out []byte) ([]byte, Action)
 	redHubBufMap map[gnet.Conn]*connBuffer
 	connSync     *sync.RWMutex
+	mu           sync.Mutex
+	addr         string
+	running      bool
+	engine       gnet.Engine
 }
 
 // connBuffer holds the buffer and commands for each connection.
@@ -253,6 +259,9 @@ func NewRedHub(
 // The engine parameter provides access to server-wide operations.
 // Typically returns gnet.None to indicate normal startup.
 func (rs *RedHub) OnBoot(eng gnet.Engine) (action gnet.Action) {
+	rs.mu.Lock()
+	rs.engine = eng
+	rs.mu.Unlock()
 	return gnet.None
 }
 
@@ -427,5 +436,34 @@ func ListenAndServe(addr string, options Options, rh *RedHub) error {
 		opts = append(opts, gnet.WithEdgeTriggeredIO(true))
 	}
 
-	return gnet.Run(rh, addr, opts...)
+	rh.mu.Lock()
+	rh.addr = addr
+	rh.running = true
+	rh.mu.Unlock()
+
+	err := gnet.Run(rh, addr, opts...)
+
+	rh.mu.Lock()
+	rh.running = false
+	rh.mu.Unlock()
+
+	return err
+}
+
+// Close gracefully shuts down the RedHub server.
+//
+// This method stops the server and closes all active connections. It is safe to call
+// multiple times. If the server is not currently running, it returns an error.
+//
+// Returns an error if the server is not running or if the shutdown fails.
+func (rs *RedHub) Close() error {
+	rs.mu.Lock()
+	defer rs.mu.Unlock()
+
+	if !rs.running {
+		return errors.New("server not running")
+	}
+
+	rs.running = false
+	return rs.engine.Stop(context.Background())
 }

redhub_test.go

@@ -310,3 +310,68 @@ func TestShutdownAction(t *testing.T) {
 	action := rh.OnTraffic(mock)
 	assert.Equal(t, gnet.Close, action)
 }
+
+func TestClose_NotRunning(t *testing.T) {
+	rh := NewRedHub(nil, nil, func(cmd resp.Command, out []byte) ([]byte, Action) {
+		return out, None
+	})
+
+	err := rh.Close()
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "server not running")
+}
+
+func TestClose_Integration(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test in short mode")
+	}
+
+	rh := NewRedHub(
+		func(c *Conn) (out []byte, action Action) {
+			return nil, None
+		},
+		func(c *Conn, err error) (action Action) {
+			return None
+		},
+		func(cmd resp.Command, out []byte) ([]byte, Action) {
+			return resp.AppendString(out, "OK"), None
+		},
+	)
+
+	// Start server in a goroutine
+	serverErr := make(chan error, 1)
+	go func() {
+		serverErr <- ListenAndServe("tcp://127.0.0.1:16379", Options{Multicore: false}, rh)
+	}()
+
+	// Wait for server to start
+	time.Sleep(100 * time.Millisecond)
+
+	// Test that server is running
+	conn, err := net.DialTimeout("tcp", "127.0.0.1:16379", time.Second)
+	assert.NoError(t, err)
+	assert.NotNil(t, conn)
+	conn.Close()
+
+	// Close the server
+	err = rh.Close()
+	assert.NoError(t, err)
+
+	// Wait a moment for server to stop
+	time.Sleep(200 * time.Millisecond)
+
+	// Verify connection fails after close
+	conn, err = net.DialTimeout("tcp", "127.0.0.1:16379", 200*time.Millisecond)
+	if err == nil {
+		conn.Close()
+		t.Error("Expected connection error after server close")
+	}
+
+	// Verify server goroutine returns gracefully (no error when stopped via Close)
+	select {
+	case err := <-serverErr:
+		assert.NoError(t, err)
+	case <-time.After(2 * time.Second):
+		t.Error("Server did not stop within timeout")
+	}
+}