Fix incorrect threading issues when using Matterircd's default threading

When using mattericd's default threading, the msgMap is populated with
message/thred IDs and never removed. This means that when we cycle
past 4k, we can have entries with duplicate counters causing issues
when replying to threads.

This fixes it by introducing an index.

mm-go-irckit/server_commands.go

@@ -478,16 +478,11 @@ func parseReactionToMsg(u *User, msg *irc.Message, channelID string) bool {
 			logger.Errorf("couldn't parseint %s: %s", msgID, err)
 		}
 
-		u.msgMapMutex.RLock()
-		defer u.msgMapMutex.RUnlock()
+		u.msgMapIndexMutex.RLock()
+		defer u.msgMapIndexMutex.RUnlock()
 
-		m := u.msgMap[channelID]
-
-		for k, v := range m {
-			if v == int(id) {
-				msgID = k
-				break
-			}
+		if _, ok := u.msgMapIndex[channelID][int(id)]; ok {
+			msgID = u.msgMapIndex[channelID][int(id)]
 		}
 	}
 
@@ -549,17 +544,11 @@ func parseModifyMsg(u *User, msg *irc.Message, channelID string) bool {
 			logger.Errorf("couldn't parseint %s: %s", matches[1], err)
 		}
 
-		u.msgMapMutex.RLock()
-		defer u.msgMapMutex.RUnlock()
+		u.msgMapIndexMutex.RLock()
+		defer u.msgMapIndexMutex.RUnlock()
 
-		m := u.msgMap[channelID]
-
-		for k, v := range m {
-			if v != int(id) {
-				continue
-			}
-
-			msgID = k
+		if _, ok := u.msgMapIndex[channelID][int(id)]; ok {
+			msgID = u.msgMapIndex[channelID][int(id)]
 
 			u.msgLastMutex.Lock()
 			defer u.msgLastMutex.Unlock()
@@ -619,15 +608,11 @@ func parseThreadID(u *User, msg *irc.Message, channelID string) (string, string)
 			return "", ""
 		}
 
-		u.msgMapMutex.RLock()
-		defer u.msgMapMutex.RUnlock()
-
-		m := u.msgMap[channelID]
+		u.msgMapIndexMutex.RLock()
+		defer u.msgMapIndexMutex.RUnlock()
 
-		for k, v := range m {
-			if v == int(id) {
-				return k, matches[2]
-			}
+		if _, ok := u.msgMapIndex[channelID][int(id)]; ok {
+			return u.msgMapIndex[channelID][int(id)], matches[2]
 		}
 	case len(matches[1]) == 26:
 		return matches[1], matches[2]

mm-go-irckit/userbridge.go

@@ -43,8 +43,10 @@ type UserBridge struct {
 	msgLastMutex sync.RWMutex         //nolint:structcheck
 	msgLast      map[string][2]string //nolint:structcheck
 
-	msgMapMutex sync.RWMutex              //nolint:structcheck
-	msgMap      map[string]map[string]int //nolint:structcheck
+	msgMapMutex      sync.RWMutex              //nolint:structcheck
+	msgMap           map[string]map[string]int //nolint:structcheck
+	msgMapIndexMutex sync.RWMutex              //nolint:structcheck
+	msgMapIndex      map[string]map[int]string //nolint:structcheck
 
 	updateCounterMutex sync.Mutex           //nolint:structcheck
 	updateCounter      map[string]time.Time //nolint:structcheck
@@ -62,6 +64,7 @@ func NewUserBridge(c net.Conn, srv Server, cfg *viper.Viper, db *bolt.DB) *User
 	u.lastViewedAtDB = db
 	u.msgLast = make(map[string][2]string)
 	u.msgMap = make(map[string]map[string]int)
+	u.msgMapIndex = make(map[string]map[int]string)
 	u.msgCounter = make(map[string]int)
 	u.updateCounter = make(map[string]time.Time)
 	u.eventChan = make(chan *bridge.Event, 1000)
@@ -913,16 +916,49 @@ func (u *User) logoutFrom(protocol string) error {
 func (u *User) increaseMsgCounter(channelID string) int {
 	u.msgCounterMutex.Lock()
 	defer u.msgCounterMutex.Unlock()
+
 	u.msgCounter[channelID]++
 
 	// max 4096 entries (0xFFF); set back to 1, 0 is used for absent.
-	if u.msgCounter[channelID] == 4096 {
+	if u.msgCounter[channelID] >= 4096 {
 		u.msgCounter[channelID] = 1
 	}
 
 	return u.msgCounter[channelID]
 }
 
+func (u *User) updateMsgMapIndex(channelID string, counter int, messageID string) {
+	u.msgMapIndexMutex.Lock()
+	defer u.msgMapIndexMutex.Unlock()
+
+	var (
+		ok    bool
+		msgID string
+	)
+
+	if _, ok = u.msgMapIndex[channelID]; !ok {
+		u.msgMapIndex[channelID] = make(map[int]string)
+	}
+
+	if msgID, ok = u.msgMapIndex[channelID][counter]; !ok {
+		u.msgMapIndex[channelID][counter] = messageID
+		return
+	}
+
+	if msgID == messageID {
+		return
+	}
+
+	// Remove previous msgID from MsgMap with the same counter.
+	if _, ok = u.msgMap[channelID][msgID]; ok {
+		logger.Warnf("Deleted %s from %s", msgID, channelID)
+		delete(u.msgMap[channelID], msgID)
+	}
+
+	u.msgMapIndex[channelID][counter] = messageID
+	return
+}
+
 func (u *User) formatContextMessage(ts, threadMsgID, msg string) string {
 	var formattedMsg string
 	switch {
@@ -971,18 +1007,19 @@ func (u *User) prefixContext(channelID, messageID, parentID, event string) strin
 		}
 
 		parentcount = u.msgMap[channelID][parentID]
+		u.updateMsgMapIndex(channelID, parentcount, messageID)
 	}
 
 	if event == "post_edited" || event == "post_deleted" || event == "reaction" {
 		if _, ok = u.msgMap[channelID][messageID]; !ok {
 			u.msgMap[channelID][messageID] = u.increaseMsgCounter(channelID)
 		}
-
 		currentcount = u.msgMap[channelID][messageID]
 	} else {
 		u.msgMap[channelID][messageID] = u.increaseMsgCounter(channelID)
 		currentcount = u.msgMap[channelID][messageID]
 	}
+	u.updateMsgMapIndex(channelID, currentcount, messageID)
 
 	if parentID != "" {
 		return fmt.Sprintf("[%s%03x,%03x]", prefixChar, parentcount, currentcount)