Fix race condition

builtin.go

@@ -177,7 +177,7 @@ func handleJOIN(c *Client, e Event) {
 
 	defer c.state.notify(c, UPDATE_STATE)
 
-	channel.addUser(user.Nick, user)
+	channel.addUser(user.Nick.Load().(string), user)
 	user.addChannel(channel.Name, channel)
 
 	// Assume extended-join (ircv3).
@@ -345,8 +345,17 @@ func handleWHO(c *Client, e Event) {
 	}
 
 	user.Host = host
-	user.Ident = ident
-	user.Mask = user.Nick + "!" + user.Ident + "@" + user.Host
+	user.Ident.Store(ident)
+
+	str := strs.Get()
+	str.MustWriteString(user.Nick.Load().(string))
+	str.MustWriteString("!")
+	str.MustWriteString(user.Ident.Load().(string))
+	str.MustWriteString("@")
+	str.MustWriteString(user.Host)
+	user.Mask.Store(str.String())
+	strs.MustPut(str)
+
 	user.Extras.Name = realname
 
 	if account != "0" {

cap.go

@@ -307,7 +307,7 @@ func handleCHGHOST(c *Client, e Event) {
 
 	user := c.state.lookupUser(e.Source.Name)
 	if user != nil {
-		user.Ident = e.Params[0]
+		user.Ident.Store(e.Params[0])
 		user.Host = e.Params[1]
 	}
 

client.go

@@ -646,7 +646,7 @@ func (c *Client) UserList() []string {
 		if usr.Stale {
 			continue
 		}
-		users = append(users, usr.Nick)
+		users = append(users, usr.Nick.Load().(string))
 	}
 
 	sort.Strings(users)
@@ -665,7 +665,7 @@ func (c *Client) Users() []*User {
 	}
 
 	sort.Slice(users, func(i, j int) bool {
-		return users[i].Nick < users[j].Nick
+		return users[i].Nick.Load().(string) < users[j].Nick.Load().(string)
 	})
 	return users
 }

handler.go

@@ -225,11 +225,7 @@ func (c *Caller) exec(command string, bg bool, client *Client, event *Event) {
 			if (strings.HasSuffix(cuid, ":bg") && !bg) || (!strings.HasSuffix(cuid, ":bg") && bg) {
 				continue
 			}
-			hi, _ := hmap.Get(cuid)
-			hndlr, ok := hi.(Handler)
-			if !ok {
-				panic("improper handler type in map")
-			}
+			hndlr, _ := hmap.Get(cuid)
 			stack = append(stack, execStack{hndlr, cuid})
 		}
 	}

state.go

@@ -92,11 +92,11 @@ func (s *state) reset(initial bool) {
 // User represents an IRC user and the state attached to them.
 type User struct {
 	// Nick is the users current nickname. rfc1459 compliant.
-	Nick string `json:"nick"`
+	Nick *MarshalableAtomicValue `json:"nick"`
 	// Ident is the users username/ident. Ident is commonly prefixed with a
 	// "~", which indicates that they do not have a identd server setup for
 	// authentication.
-	Ident string `json:"ident"`
+	Ident *MarshalableAtomicValue `json:"ident"`
 	// Host is the visible host of the users connection that the server has
 	// provided to us for their connection. May not always be accurate due to
 	// many networks spoofing/hiding parts of the hostname for privacy
@@ -104,7 +104,7 @@ type User struct {
 	Host string `json:"host"`
 
 	// Mask is the combined Nick!Ident@Host of the given user.
-	Mask string `json:"mask"`
+	Mask *MarshalableAtomicValue `json:"mask"`
 
 	// Network is the name of the IRC network where this user was found.
 	// This has been added for the purposes of girc being used in multi-client scenarios with data persistence.
@@ -366,7 +366,7 @@ func (ch *Channel) Copy() *Channel {
 	*nc = *ch
 
 	for v := range ch.UserList.IterBuffered() {
-		nc.UserList.Set(v.Val.Nick, v.Val)
+		nc.UserList.Set(v.Val.Nick.Load().(string), v.Val)
 	}
 
 	// And modes.
@@ -466,10 +466,10 @@ func (s *state) createUser(src *Source) (u *User, ok bool) {
 	mask.MustWriteString(src.Host)
 
 	u = &User{
-		Nick:        src.Name,
+		Nick:        NewAtomicString(src.Name),
 		Host:        src.Host,
-		Ident:       src.Ident,
-		Mask:        mask.String(),
+		Ident:       NewAtomicString(src.Ident),
+		Mask:        NewAtomicString(mask.String()),
 		ChannelList: cmap.New[*Channel](),
 		FirstSeen:   time.Now(),
 		LastActive:  time.Now(),
@@ -532,7 +532,7 @@ func (s *state) renameUser(from, to string) {
 		user = old
 	}
 
-	user.Nick = to
+	user.Nick.Store(to)
 	user.LastActive = time.Now()
 	s.users.Set(ToRFC1459(to), user)
 

state_test.go

@@ -123,7 +123,7 @@ func TestState(t *testing.T) {
 
 		fullUsers := c.Users()
 		for i := 0; i < len(fullUsers); i++ {
-			if fullUsers[i].Nick != users[i] {
+			if fullUsers[i].Nick.Load().(string) != users[i] {
 				t.Errorf("fullUsers nick doesn't map to same nick in UsersList: %q :: %#v", fullUsers[i].Nick, users)
 				return
 			}
@@ -138,12 +138,12 @@ func TestState(t *testing.T) {
 		adm := ch.Admins(c)
 		var admList []string
 		for i := 0; i < len(adm); i++ {
-			admList = append(admList, adm[i].Nick)
+			admList = append(admList, adm[i].Nick.Load().(string))
 		}
 		trusted := ch.Trusted(c)
 		var trustedList []string
 		for i := 0; i < len(trusted); i++ {
-			trustedList = append(trustedList, trusted[i].Nick)
+			trustedList = append(trustedList, trusted[i].Nick.Load().(string))
 		}
 
 		if !reflect.DeepEqual(admList, []string{"nick2"}) {
@@ -213,7 +213,7 @@ func TestState(t *testing.T) {
 			return
 		}
 
-		if user.Nick != "fhjones" {
+		if user.Nick.Load().(string) != "fhjones" {
 			t.Errorf("User.Nick == %q, wanted \"nick\"", user.Nick)
 			return
 		}
@@ -228,7 +228,7 @@ func TestState(t *testing.T) {
 			return
 		}
 
-		if user.Ident != "~user" {
+		if user.Ident.Load().(string) != "~user" {
 			t.Errorf("User.Ident == %q, wanted \"~user\"", user.Ident)
 			return
 		}

value.go

@@ -0,0 +1,29 @@
+package girc
+
+import (
+	"fmt"
+	"sync/atomic"
+)
+
+type MarshalableAtomicValue struct {
+	*atomic.Value
+}
+
+func (m *MarshalableAtomicValue) MarshalJSON() ([]byte, error) {
+	return []byte(fmt.Sprintf("%v", m.Value.Load())), nil
+}
+
+func (m *MarshalableAtomicValue) UnmarshalJSON(b []byte) error {
+	m.Value.Store(string(b))
+	return nil
+}
+
+func (m *MarshalableAtomicValue) String() string {
+	return m.Value.Load().(string)
+}
+
+func NewAtomicString(s string) *MarshalableAtomicValue {
+	obj := &atomic.Value{}
+	obj.Store(s)
+	return &MarshalableAtomicValue{Value: obj}
+}