From 1d43aeca2f09647221ef1de93ddca208bb8086a6 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Tue, 28 May 2019 14:12:35 +0300
Subject: [PATCH] Remove message locking as message handling is synchronous
 per-portal

---
 portal.go | 51 ++++++++++++---------------------------------------
 1 file changed, 12 insertions(+), 39 deletions(-)

diff --git a/portal.go b/portal.go
index 69828be..1e3c268 100644
--- a/portal.go
+++ b/portal.go
@@ -108,7 +108,6 @@ func (bridge *Bridge) NewPortal(dbPortal *database.Portal) *Portal {
 		bridge: bridge,
 		log:    bridge.Log.Sub(fmt.Sprintf("Portal/%s", dbPortal.Key)),
 
-		messageLocks:    make(map[types.WhatsAppMessageID]sync.Mutex),
 		recentlyHandled: [recentlyHandledLength]types.WhatsAppMessageID{},
 
 		messages: make(chan PortalMessage, 128),
@@ -134,9 +133,7 @@ type Portal struct {
 
 	avatarURL string
 
-	roomCreateLock   sync.Mutex
-	messageLocksLock sync.Mutex
-	messageLocks     map[types.WhatsAppMessageID]sync.Mutex
+	roomCreateLock sync.Mutex
 
 	recentlyHandled      [recentlyHandledLength]types.WhatsAppMessageID
 	recentlyHandledLock  sync.Mutex
@@ -188,22 +185,6 @@ func (portal *Portal) handleMessage(msg PortalMessage) {
 	}
 }
 
-func (portal *Portal) getMessageLock(messageID types.WhatsAppMessageID) sync.Mutex {
-	portal.messageLocksLock.Lock()
-	defer portal.messageLocksLock.Unlock()
-	lock, ok := portal.messageLocks[messageID]
-	if !ok {
-		portal.messageLocks[messageID] = lock
-	}
-	return lock
-}
-
-func (portal *Portal) deleteMessageLock(messageID types.WhatsAppMessageID) {
-	portal.messageLocksLock.Lock()
-	delete(portal.messageLocks, messageID)
-	portal.messageLocksLock.Unlock()
-}
-
 func (portal *Portal) isRecentlyHandled(id types.WhatsAppMessageID) bool {
 	start := portal.recentlyHandledIndex
 	for i := start; i != start; i = (i - 1) % recentlyHandledLength {
@@ -252,25 +233,19 @@ func (portal *Portal) markHandled(source *User, message *waProto.WebMessageInfo,
 	portal.recentlyHandled[index] = msg.JID
 }
 
-func (portal *Portal) startHandling(info whatsapp.MessageInfo) (*sync.Mutex, bool) {
-	if portal.lastMessageTs > info.Timestamp+1 || portal.isRecentlyHandled(info.Id) {
-		return nil, false
-	}
-	lock := portal.getMessageLock(info.Id)
-	lock.Lock()
-	if portal.isDuplicate(info.Id) {
-		lock.Unlock()
-		return nil, false
+func (portal *Portal) startHandling(info whatsapp.MessageInfo) bool {
+	if portal.lastMessageTs > info.Timestamp+1 ||
+		portal.isRecentlyHandled(info.Id) ||
+		portal.isDuplicate(info.Id) {
+		return false
 	}
 	portal.lastMessageTs = info.Timestamp
-	return &lock, true
+	return true
 }
 
 func (portal *Portal) finishHandling(source *User, message *waProto.WebMessageInfo, mxid types.MatrixEventID) {
 	portal.markHandled(source, message, mxid)
-	id := message.GetKey().GetId()
-	portal.deleteMessageLock(id)
-	portal.log.Debugln("Handled message", id, "->", mxid)
+	portal.log.Debugln("Handled message", message.GetKey().GetId(), "->", mxid)
 }
 
 func (portal *Portal) SyncParticipants(metadata *whatsappExt.GroupInfo) {
@@ -582,6 +557,8 @@ func (portal *Portal) FillInitialHistory(user *User) error {
 	if portal.bridge.Config.Bridge.InitialHistoryFill == 0 {
 		return nil
 	}
+	portal.backfillLock.Lock()
+	defer portal.backfillLock.Unlock()
 	n := portal.bridge.Config.Bridge.InitialHistoryFill
 	portal.log.Infoln("Filling initial history, maximum", n, "messages")
 	var messages []interface{}
@@ -795,11 +772,9 @@ func (portal *Portal) HandleTextMessage(source *User, message whatsapp.TextMessa
 		return
 	}
 
-	lock, ok := portal.startHandling(message.Info)
-	if !ok {
+	if !portal.startHandling(message.Info) {
 		return
 	}
-	defer lock.Unlock()
 
 	intent := portal.GetMessageIntent(source, message.Info)
 	if intent == nil {
@@ -828,11 +803,9 @@ func (portal *Portal) HandleMediaMessage(source *User, download func() ([]byte,
 		return
 	}
 
-	lock, ok := portal.startHandling(info)
-	if !ok {
+	if !portal.startHandling(info) {
 		return
 	}
-	defer lock.Unlock()
 
 	intent := portal.GetMessageIntent(source, info)
 	if intent == nil {