Add locks and other sync stuff

README.md

@@ -21,7 +21,7 @@ precompiled executables. For now, you can either download
 a CI build from [dl.maunium.net/programs/gomuks](https://dl.maunium.net/programs/gomuks)
 or compile from source:
 
-0. Install [Go](https://golang.org/) 1.11 or higher
+0. Install [Go](https://golang.org/) 1.12 or higher
 1. Clone the repo: `git clone https://github.com/tulir/gomuks.git && cd gomuks`
 2. Build: `go build`
 

debug/debug.go

@@ -95,7 +95,7 @@ func PrettyPanic(panic interface{}) {
 	var buf bytes.Buffer
 	fmt.Fprintln(&buf, panic)
 	buf.Write(debug.Stack())
-	err := ioutil.WriteFile(traceFile, buf.Bytes(), 0644)
+	err := ioutil.WriteFile(traceFile, buf.Bytes(), 0640)
 
 	if err != nil {
 		fmt.Println("Saving the stack trace to", traceFile, "failed:")

go.mod

@@ -4,22 +4,26 @@ go 1.12
 
 require (
 	github.com/alecthomas/chroma v0.6.3
+	github.com/alecthomas/kong v0.1.16 // indirect
+	github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1 // indirect
 	github.com/disintegration/imaging v1.6.0
 	github.com/kyokomi/emoji v2.1.0+incompatible
 	github.com/lithammer/fuzzysearch v1.0.2
-	github.com/lucasb-eyer/go-colorful v1.0.1
+	github.com/lucasb-eyer/go-colorful v1.0.2
+	github.com/mattn/go-colorable v0.1.1 // indirect
+	github.com/mattn/go-isatty v0.0.7 // indirect
 	github.com/mattn/go-runewidth v0.0.4
 	github.com/nu7hatch/gouuid v0.0.0-20131221200532-179d4d0c4d8d // indirect
 	github.com/russross/blackfriday/v2 v2.0.1
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
+	github.com/stretchr/objx v0.2.0 // indirect
 	go.etcd.io/bbolt v1.3.2
-	golang.org/x/crypto v0.0.0-20190404164418-38d8ce5564a5 // indirect
+	golang.org/x/image v0.0.0-20190424155947-59b11bec70c7
-	golang.org/x/image v0.0.0-20190321063152-3fc05d484e9f
+	golang.org/x/net v0.0.0-20190424112056-4829fb13d2c6
-	golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3
+	gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 // indirect
-	golang.org/x/sys v0.0.0-20190410170021-cc4d4f50624c // indirect
 	gopkg.in/toast.v1 v1.0.0-20180812000517-0a84660828b2 // indirect
 	gopkg.in/yaml.v2 v2.2.2
 	maunium.net/go/mautrix v0.1.0-alpha.3.0.20190410194750-53c7c9d954c8
-	maunium.net/go/mauview v0.0.0-20190406150001-ad4a4e562f9e
+	maunium.net/go/mauview v0.0.0-20190426104003-3e5387b8a125
-	maunium.net/go/tcell v0.0.0-20190406145848-d520315b0ddb
+	maunium.net/go/tcell v0.0.0-20190426103942-24a060c2189b
 )

go.sum

@@ -1,11 +1,15 @@
+github.com/DATA-DOG/go-sqlmock v1.3.3/go.mod h1:f/Ixk793poVmq4qj/V1dPUg2JEAKC73Q5eFN3EC/SaM=
 github.com/alecthomas/assert v0.0.0-20170929043011-405dbfeb8e38/go.mod h1:r7bzyVFMNntcxPZXK3/+KdruV1H5KSlyVY0gc+NgInI=
 github.com/alecthomas/chroma v0.6.3 h1:8H1D0yddf0mvgvO4JDBKnzLd9ERmzzAijBxnZXGV/FA=
 github.com/alecthomas/chroma v0.6.3/go.mod h1:quT2EpvJNqkuPi6DmBHB+E33FXBgBBPzyH5++Dn1LPc=
 github.com/alecthomas/colour v0.0.0-20160524082231-60882d9e2721/go.mod h1:QO9JBoKquHd+jz9nshCh40fOfO+JzsoXy8qTHF68zU0=
 github.com/alecthomas/kong v0.1.15/go.mod h1:0m2VYms8rH0qbCqVB2gvGHk74bqLIq0HXjCs5bNbNQU=
+github.com/alecthomas/kong v0.1.16/go.mod h1:0m2VYms8rH0qbCqVB2gvGHk74bqLIq0HXjCs5bNbNQU=
 github.com/alecthomas/repr v0.0.0-20180818092828-117648cd9897/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
+github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
 github.com/danwakefield/fnmatch v0.0.0-20160403171240-cbb64ac3d964 h1:y5HC9v93H5EPKqaS1UYVg1uYah5Xf51mBfIoWehClUQ=
 github.com/danwakefield/fnmatch v0.0.0-20160403171240-cbb64ac3d964/go.mod h1:Xd9hchkHSWYkEqJwUGisez3G1QY8Ryz0sdWrLPMGjLk=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/disintegration/imaging v1.6.0 h1:nVPXRUUQ36Z7MNf0O77UzgnOb1mkMMor7lmJMJXc/mA=
@@ -20,8 +24,13 @@ github.com/lithammer/fuzzysearch v1.0.2 h1:AjCE2iwc5y+8K+h2nXVc0Pmrpjvu+JVqMgiZ0
 github.com/lithammer/fuzzysearch v1.0.2/go.mod h1:bvAJyokfCQ7Vknrd4Kgc+izmMrPj5CiBAu2t6rK1Kak=
 github.com/lucasb-eyer/go-colorful v1.0.1 h1:nKJRBvZWPzvkwB4sY8A3U4zgqLf2Y9c02yzPsbXu/5c=
 github.com/lucasb-eyer/go-colorful v1.0.1/go.mod h1:tLy1nWSoU0DGtxQyNRrUmb6PUiB7usbds6gd97XTXwA=
+github.com/lucasb-eyer/go-colorful v1.0.2 h1:mCMFu6PgSozg9tDNMMK3g18oJBX7oYGrC09mS6CXfO4=
+github.com/lucasb-eyer/go-colorful v1.0.2/go.mod h1:0MS4r+7BZKSJ5mw4/S5MPN+qHFF1fYclkSPilDOKW0s=
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
+github.com/mattn/go-colorable v0.1.1/go.mod h1:FuOcm+DKB9mbwrcAfNl7/TZVBZ6rcnceauSikq3lYCQ=
 github.com/mattn/go-isatty v0.0.4/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=
+github.com/mattn/go-isatty v0.0.5/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.7/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
 github.com/mattn/go-runewidth v0.0.4 h1:2BvfKmzob6Bmd4YsL0zygOqfdFnK7GR4QL06Do4/p7Y=
 github.com/mattn/go-runewidth v0.0.4/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/nu7hatch/gouuid v0.0.0-20131221200532-179d4d0c4d8d h1:VhgPp6v9qf9Agr/56bj7Y/xa04UccTW04VP0Qed4vnQ=
@@ -35,8 +44,11 @@ github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQD
 github.com/sergi/go-diff v1.0.0/go.mod h1:0CfEIISq7TuYL3j771MWULgwwjU+GofnZX9QAmXWZgo=
 github.com/shurcooL/sanitized_anchor_name v1.0.0 h1:PdmoCO6wvbs+7yrJyMORt4/BmY5IYyJwS/kOiWx8mHo=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.2.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoHMkEqE=
 github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/zyedidia/clipboard v0.0.0-20180718195219-bd31d747117d h1:Lhqt2eo+rgM8aswvM7nTtAMVm8ARPWzkE9n6eZDOccY=
 github.com/zyedidia/clipboard v0.0.0-20180718195219-bd31d747117d/go.mod h1:WDk3p8GiZV9+xFWlSo8qreeoLhW6Ik692rqXk+cNeRY=
 go.etcd.io/bbolt v1.3.2 h1:Z/90sZLPOeCy2PwprqkFa25PdkusRzaj9P8zm/KNyvk=
@@ -44,23 +56,38 @@ go.etcd.io/bbolt v1.3.2/go.mod h1:IbVyRI1SCnLcuJnV2u8VeU0CEYM7e686BmAb1XKL+uU=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190325154230-a5d413f7728c/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190404164418-38d8ce5564a5/go.mod h1:WFFai1msRO1wXaEeE5yQxYXgSfI8pQAWXbQop6sCtWE=
+golang.org/x/crypto v0.0.0-20190424203555-c05e17bb3b2d/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/image v0.0.0-20180708004352-c73c2afc3b81/go.mod h1:ux5Hcp/YLpHSI86hEcLt0YII63i6oz57MZXIpbrjZUs=
 golang.org/x/image v0.0.0-20190321063152-3fc05d484e9f h1:FO4MZ3N56GnxbqxGKqh+YTzUWQ2sDwtFQEZgLOxh9Jc=
 golang.org/x/image v0.0.0-20190321063152-3fc05d484e9f/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
+golang.org/x/image v0.0.0-20190424155947-59b11bec70c7 h1:OIchhgIITCxOyycwe8n9adxV37/WqbetxrpXNm7oPqI=
+golang.org/x/image v0.0.0-20190424155947-59b11bec70c7/go.mod h1:kZ7UVZpmo3dzQBMxlp+ypCbDeSB+sBbTgSJuh5dn5js=
 golang.org/x/net v0.0.0-20190110200230-915654e7eabc/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190326090315-15845e8f865b/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190424112056-4829fb13d2c6 h1:FP8hkuE6yUEaJnK7O2eTuejKWwW+Rhfj80dQ2JcKxCU=
+golang.org/x/net v0.0.0-20190424112056-4829fb13d2c6/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20181128092732-4ed8d59d0b35/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190322080309-f49334f85ddc/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190403152447-81d4e9dc473e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190405154228-4b34438f7a67/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190410170021-cc4d4f50624c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190425145619-16072639606e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20190425222832-ad9eeb80039a/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 gopkg.in/DATA-DOG/go-sqlmock.v1 v1.3.0/go.mod h1:OdE7CF6DbADk7lN8LIKRzRJTTZXIjtWgA5THM5lhBAw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/toast.v1 v1.0.0-20180812000517-0a84660828b2 h1:MZF6J7CV6s/h0HBkfqebrYfKCVEo5iN+wzE4QhV3Evo=
 gopkg.in/toast.v1 v1.0.0-20180812000517-0a84660828b2/go.mod h1:s1Sn2yZos05Qfs7NKt867Xe18emOmtsO3eAKbDaon0o=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=

matrix/matrix.go

@@ -178,8 +178,10 @@ func (c *Container) UpdatePushRules() {
 	resp, err := pushrules.GetPushRules(c.client)
 	if err != nil {
 		debug.Print("Failed to fetch push rules:", err)
-	}
+		c.config.PushRules = &pushrules.PushRuleset{}
+	} else {
 		c.config.PushRules = resp
+	}
 	c.config.SavePushRules()
 }
 

matrix/pushrules/ruleset.go

@@ -75,7 +75,7 @@ func (rs *PushRuleset) MarshalJSON() ([]byte, error) {
 
 // DefaultPushActions is the value returned if none of the rule
 // collections in a Ruleset match the event given to GetActions()
-var DefaultPushActions = make(PushActionArray, 0)
+var DefaultPushActions = PushActionArray{&PushAction{Action: ActionDontNotify}}
 
 // GetActions matches the given event against all of the push rule
 // collections in this push ruleset in the order of priority as
@@ -85,6 +85,9 @@ func (rs *PushRuleset) GetActions(room Room, event *mautrix.Event) (match PushAc
 	arrays := []PushRuleCollection{rs.Override, rs.Content, rs.Room, rs.Sender, rs.Underride}
 	// Loop until one of the push rule collections matches the room/event combo.
 	for _, pra := range arrays {
+		if pra == nil {
+			continue
+		}
 		if match = pra.GetActions(room, event); match != nil {
 			// Match found, return it.
 			return

matrix/rooms/room.go

@@ -57,7 +57,6 @@ type UnreadMessage struct {
 	Highlight bool
 }
 
-
 // Room represents a single Matrix room.
 type Room struct {
 	*mautrix.Room
@@ -101,26 +100,7 @@ type Room struct {
 	// The list of aliases. Directly fetched from the m.room.aliases state event.
 	aliasesCache []string
 
-	// fetchHistoryLock is used to make sure multiple goroutines don't fetch
+	lock sync.RWMutex
-	// history for this room at the same time.
-	fetchHistoryLock *sync.Mutex
-}
-
-// LockHistory locks the history fetching mutex.
-// If the mutex is nil, it will be created.
-func (room *Room) LockHistory() {
-	if room.fetchHistoryLock == nil {
-		room.fetchHistoryLock = &sync.Mutex{}
-	}
-	room.fetchHistoryLock.Lock()
-}
-
-// UnlockHistory unlocks the history fetching mutex.
-// If the mutex is nil, this does nothing.
-func (room *Room) UnlockHistory() {
-	if room.fetchHistoryLock != nil {
-		room.fetchHistoryLock.Unlock()
-	}
 }
 
 func (room *Room) Load(path string) error {
@@ -130,6 +110,8 @@ func (room *Room) Load(path string) error {
 	}
 	defer file.Close()
 	dec := gob.NewDecoder(file)
+	room.lock.Lock()
+	defer room.lock.Unlock()
 	return dec.Decode(room)
 }
 
@@ -140,11 +122,15 @@ func (room *Room) Save(path string) error {
 	}
 	defer file.Close()
 	enc := gob.NewEncoder(file)
+	room.lock.RLock()
+	defer room.lock.RUnlock()
 	return enc.Encode(room)
 }
 
 // MarkRead clears the new message statuses on this room.
 func (room *Room) MarkRead(eventID string) bool {
+	room.lock.Lock()
+	defer room.lock.Unlock()
 	if room.lastMarkedRead == eventID {
 		return false
 	}
@@ -164,6 +150,8 @@ func (room *Room) MarkRead(eventID string) bool {
 }
 
 func (room *Room) UnreadCount() int {
+	room.lock.Lock()
+	defer room.lock.Unlock()
 	if room.unreadCountCache == nil {
 		room.unreadCountCache = new(int)
 		for _, unreadMessage := range room.UnreadMessages {
@@ -176,6 +164,8 @@ func (room *Room) UnreadCount() int {
 }
 
 func (room *Room) Highlighted() bool {
+	room.lock.Lock()
+	defer room.lock.Unlock()
 	if room.highlightCache == nil {
 		room.highlightCache = new(bool)
 		for _, unreadMessage := range room.UnreadMessages {
@@ -193,6 +183,8 @@ func (room *Room) HasNewMessages() bool {
 }
 
 func (room *Room) AddUnread(eventID string, counted, highlight bool) {
+	room.lock.Lock()
+	defer room.lock.Unlock()
 	room.UnreadMessages = append(room.UnreadMessages, UnreadMessage{
 		EventID:   eventID,
 		Counted:   counted,
@@ -213,6 +205,8 @@ func (room *Room) AddUnread(eventID string, counted, highlight bool) {
 }
 
 func (room *Room) Tags() []RoomTag {
+	room.lock.RLock()
+	defer room.lock.RUnlock()
 	if len(room.RawTags) == 0 {
 		if room.IsDirect {
 			return []RoomTag{{"net.maunium.gomuks.fake.direct", "0.5"}}
@@ -225,6 +219,8 @@ func (room *Room) Tags() []RoomTag {
 // UpdateState updates the room's current state with the given Event. This will clobber events based
 // on the type/state_key combination.
 func (room *Room) UpdateState(event *mautrix.Event) {
+	room.lock.Lock()
+	defer room.lock.Unlock()
 	_, exists := room.State[event.Type]
 	if !exists {
 		room.State[event.Type] = make(map[string]*mautrix.Event)
@@ -269,13 +265,15 @@ func (room *Room) UpdateState(event *mautrix.Event) {
 
 // GetStateEvent returns the state event for the given type/state_key combo, or nil.
 func (room *Room) GetStateEvent(eventType mautrix.EventType, stateKey string) *mautrix.Event {
+	room.lock.RLock()
+	defer room.lock.RUnlock()
 	stateEventMap, _ := room.State[eventType]
 	event, _ := stateEventMap[stateKey]
 	return event
 }
 
-// GetStateEvents returns the state events for the given type.
+// getStateEvents returns the state events for the given type.
-func (room *Room) GetStateEvents(eventType mautrix.EventType) map[string]*mautrix.Event {
+func (room *Room) getStateEvents(eventType mautrix.EventType) map[string]*mautrix.Event {
 	stateEventMap, _ := room.State[eventType]
 	return stateEventMap
 }
@@ -309,11 +307,13 @@ func (room *Room) GetCanonicalAlias() string {
 // GetAliases returns the list of aliases that point to this room.
 func (room *Room) GetAliases() []string {
 	if room.aliasesCache == nil {
-		aliasEvents := room.GetStateEvents(mautrix.StateAliases)
+		room.lock.RLock()
+		aliasEvents := room.getStateEvents(mautrix.StateAliases)
 		room.aliasesCache = []string{}
 		for _, event := range aliasEvents {
 			room.aliasesCache = append(room.aliasesCache, event.Content.Aliases...)
 		}
+		room.lock.RUnlock()
 	}
 	return room.aliasesCache
 }
@@ -394,7 +394,8 @@ func (room *Room) GetTitle() string {
 // createMemberCache caches all member events into a easily processable MXID -> *Member map.
 func (room *Room) createMemberCache() map[string]*mautrix.Member {
 	cache := make(map[string]*mautrix.Member)
-	events := room.GetStateEvents(mautrix.StateMember)
+	room.lock.RLock()
+	events := room.getStateEvents(mautrix.StateMember)
 	room.firstMemberCache = nil
 	if events != nil {
 		for userID, event := range events {
@@ -411,7 +412,10 @@ func (room *Room) createMemberCache() map[string]*mautrix.Member {
 			}
 		}
 	}
+	room.lock.RUnlock()
+	room.lock.Lock()
 	room.memberCache = cache
+	room.lock.Unlock()
 	return cache
 }
 
@@ -432,7 +436,9 @@ func (room *Room) GetMember(userID string) *mautrix.Member {
 	if len(room.memberCache) == 0 {
 		room.createMemberCache()
 	}
+	room.lock.RLock()
 	member, _ := room.memberCache[userID]
+	room.lock.RUnlock()
 	return member
 }
 
@@ -445,7 +451,6 @@ func (room *Room) GetSessionOwner() string {
 func NewRoom(roomID, owner string) *Room {
 	return &Room{
 		Room: mautrix.NewRoom(roomID),
-		fetchHistoryLock: &sync.Mutex{},
 		SessionUserID: owner,
 	}
 }

matrix/sync.go

@@ -107,6 +107,8 @@ func NewGomuksSyncer(session SyncerSession) *GomuksSyncer {
 // ProcessResponse processes a Matrix sync response.
 func (s *GomuksSyncer) ProcessResponse(res *mautrix.RespSync, since string) (err error) {
 	debug.Print("Received sync response")
+//	dat, _ := json.MarshalIndent(res, "", "  ")
+//	debug.Print(string(dat))
 	s.processSyncEvents(nil, res.Presence.Events, EventSourcePresence)
 	s.processSyncEvents(nil, res.AccountData.Events, EventSourceAccountData)
 

ui/message-view.go

@@ -20,6 +20,8 @@ import (
 	"fmt"
 	"math"
 	"strings"
+	"sync"
+	"sync/atomic"
 
 	"github.com/mattn/go-runewidth"
 
@@ -43,19 +45,23 @@ type MessageView struct {
 	DateFormat      string
 	TimestampFormat string
 	TimestampWidth  int
-	LoadingMessages bool
 
-	widestSender int
+	// Used for locking
-	width        int
+	loadingMessages int32
-	height       int
+
-	prevWidth    int
+	_widestSender uint32
-	prevHeight   int
+	_width        uint32
+	_height       uint32
+	_prevWidth    uint32
+	_prevHeight   uint32
 	prevMsgCount  int
 	prevPrefs     config.UserPreferences
 
+	messageIDLock sync.RWMutex
 	messageIDs    map[string]messages.UIMessage
+	messagesLock  sync.RWMutex
 	messages      []messages.UIMessage
-
+	msgBufferLock sync.RWMutex
 	msgBuffer     []messages.UIMessage
 }
 
@@ -72,19 +78,20 @@ func NewMessageView(parent *RoomView) *MessageView {
 		messageIDs: make(map[string]messages.UIMessage),
 		msgBuffer:  make([]messages.UIMessage, 0),
 
-		width:        80,
+		_width:        80,
-		widestSender: 5,
+		_widestSender: 5,
-		prevWidth:    -1,
+		_prevWidth:    0,
-		prevHeight:   -1,
+		_prevHeight:   0,
 		prevMsgCount:  -1,
 	}
 }
 
 func (view *MessageView) updateWidestSender(sender string) {
-	if len(sender) > view.widestSender {
+	if len(sender) > int(view._widestSender) {
-		view.widestSender = len(sender)
+		if len(sender) > view.MaxSenderWidth {
-		if view.widestSender > view.MaxSenderWidth {
+			atomic.StoreUint32(&view._widestSender, uint32(view.MaxSenderWidth))
-			view.widestSender = view.MaxSenderWidth
+		} else {
+			atomic.StoreUint32(&view._widestSender, uint32(len(sender)))
 		}
 	}
 }
@@ -109,22 +116,21 @@ func (view *MessageView) AddMessage(ifcMessage ifc.Message, direction MessageDir
 	}
 
 	var oldMsg messages.UIMessage
-	var messageExists bool
+	if oldMsg = view.getMessageByID(message.ID()); oldMsg != nil {
-	if oldMsg, messageExists = view.messageIDs[message.ID()]; messageExists {
 		view.replaceMessage(oldMsg, message)
 		direction = IgnoreMessage
-	} else if oldMsg, messageExists = view.messageIDs[message.TxnID()]; messageExists {
+	} else if oldMsg = view.getMessageByID(message.TxnID()); oldMsg != nil {
 		view.replaceMessage(oldMsg, message)
-		delete(view.messageIDs, message.TxnID())
+		view.deleteMessageID(message.TxnID())
 		direction = IgnoreMessage
 	}
 
 	view.updateWidestSender(message.Sender())
 
-	width := view.width
+	width := view.width()
 	bare := view.config.Preferences.BareMessageView
 	if !bare {
-		width -= view.TimestampWidth + TimestampSenderGap + view.widestSender + SenderMessageGap
+		width -= view.TimestampWidth + TimestampSenderGap + view.widestSender() + SenderMessageGap
 	}
 	message.CalculateBuffer(view.config.Preferences, width)
 
@@ -140,18 +146,22 @@ func (view *MessageView) AddMessage(ifcMessage ifc.Message, direction MessageDir
 		if view.ScrollOffset > 0 {
 			view.ScrollOffset += message.Height()
 		}
+		view.messagesLock.Lock()
 		if len(view.messages) > 0 && !view.messages[len(view.messages)-1].SameDate(message) {
 			view.messages = append(view.messages, makeDateChange(), message)
 		} else {
 			view.messages = append(view.messages, message)
 		}
+		view.messagesLock.Unlock()
 		view.appendBuffer(message)
 	} else if direction == PrependMessage {
+		view.messagesLock.Lock()
 		if len(view.messages) > 0 && !view.messages[0].SameDate(message) {
 			view.messages = append([]messages.UIMessage{message, makeDateChange()}, view.messages...)
 		} else {
 			view.messages = append([]messages.UIMessage{message}, view.messages...)
 		}
+		view.messagesLock.Unlock()
 	} else if oldMsg != nil {
 		view.replaceBuffer(oldMsg, message)
 	} else {
@@ -160,31 +170,62 @@ func (view *MessageView) AddMessage(ifcMessage ifc.Message, direction MessageDir
 	}
 
 	if len(message.ID()) > 0 {
-		view.messageIDs[message.ID()] = message
+		view.setMessageID(message)
 	}
 }
 
+func (view *MessageView) replaceMessage(original messages.UIMessage, new messages.UIMessage) {
+	if len(new.ID()) > 0 {
+		view.setMessageID(new)
+	}
+	view.messagesLock.Lock()
+	for index, msg := range view.messages {
+		if msg == original {
+			view.messages[index] = new
+		}
+	}
+	view.messagesLock.Unlock()
+}
+
+func (view *MessageView) getMessageByID(id string) messages.UIMessage {
+	view.messageIDLock.RLock()
+	defer view.messageIDLock.RUnlock()
+	msg, ok := view.messageIDs[id]
+	if !ok {
+		return nil
+	}
+	return msg
+}
+
+func (view *MessageView) deleteMessageID(id string) {
+	view.messageIDLock.Lock()
+	delete(view.messageIDs, id)
+	view.messageIDLock.Unlock()
+}
+
+func (view *MessageView) setMessageID(message messages.UIMessage) {
+	view.messageIDLock.Lock()
+	view.messageIDs[message.ID()] = message
+	view.messageIDLock.Unlock()
+}
+
 func (view *MessageView) appendBuffer(message messages.UIMessage) {
+	view.msgBufferLock.Lock()
+	view.appendBufferUnlocked(message)
+	view.msgBufferLock.Unlock()
+}
+
+func (view *MessageView) appendBufferUnlocked(message messages.UIMessage) {
 	for i := 0; i < message.Height(); i++ {
 		view.msgBuffer = append(view.msgBuffer, message)
 	}
 	view.prevMsgCount++
 }
 
-func (view *MessageView) replaceMessage(original messages.UIMessage, new messages.UIMessage) {
-	if len(new.ID()) > 0 {
-		view.messageIDs[new.ID()] = new
-	}
-	for index, msg := range view.messages {
-		if msg == original {
-			view.messages[index] = new
-		}
-	}
-}
-
 func (view *MessageView) replaceBuffer(original messages.UIMessage, new messages.UIMessage) {
 	start := -1
 	end := -1
+	view.msgBufferLock.RLock()
 	for index, meta := range view.msgBuffer {
 		if meta == original {
 			if start == -1 {
@@ -195,6 +236,7 @@ func (view *MessageView) replaceBuffer(original messages.UIMessage, new messages
 			break
 		}
 	}
+	view.msgBufferLock.RUnlock()
 
 	if start == -1 {
 		debug.Print("Called replaceBuffer() with message that was not in the buffer:", original)
@@ -208,9 +250,10 @@ func (view *MessageView) replaceBuffer(original messages.UIMessage, new messages
 	}
 
 	if new.Height() == 0 {
-		new.CalculateBuffer(view.prevPrefs, view.prevWidth)
+		new.CalculateBuffer(view.prevPrefs, view.prevWidth())
 	}
 
+	view.msgBufferLock.Lock()
 	if new.Height() != end-start {
 		metaBuffer := view.msgBuffer[0:start]
 		for i := 0; i < new.Height(); i++ {
@@ -222,17 +265,20 @@ func (view *MessageView) replaceBuffer(original messages.UIMessage, new messages
 			view.msgBuffer[i] = new
 		}
 	}
+	view.msgBufferLock.Unlock()
 }
 
 func (view *MessageView) recalculateBuffers() {
 	prefs := view.config.Preferences
-	recalculateMessageBuffers := view.width != view.prevWidth ||
+	recalculateMessageBuffers := view.width() != view.prevWidth() ||
 		view.prevPrefs.BareMessageView != prefs.BareMessageView ||
 		view.prevPrefs.DisableImages != prefs.DisableImages
+	view.messagesLock.RLock()
+	view.msgBufferLock.Lock()
 	if recalculateMessageBuffers || len(view.messages) != view.prevMsgCount {
-		width := view.width
+		width := view.width()
 		if !prefs.BareMessageView {
-			width -= view.TimestampWidth + TimestampSenderGap + view.widestSender + SenderMessageGap
+			width -= view.TimestampWidth + TimestampSenderGap + view.widestSender() + SenderMessageGap
 		}
 		view.msgBuffer = []messages.UIMessage{}
 		view.prevMsgCount = 0
@@ -244,11 +290,12 @@ func (view *MessageView) recalculateBuffers() {
 			if recalculateMessageBuffers {
 				message.CalculateBuffer(prefs, width)
 			}
-			view.appendBuffer(message)
+			view.appendBufferUnlocked(message)
 		}
 	}
-	view.prevHeight = view.height
+	view.msgBufferLock.Unlock()
-	view.prevWidth = view.width
+	view.messagesLock.RUnlock()
+	view.updatePrevSize()
 	view.prevPrefs = prefs
 }
 
@@ -309,19 +356,21 @@ func (view *MessageView) OnMouseEvent(event mauview.MouseEvent) bool {
 		return true
 	case tcell.Button1:
 		x, y := event.Position()
-		line := view.TotalHeight() - view.ScrollOffset - view.height + y
+		line := view.TotalHeight() - view.ScrollOffset - view.Height() + y
 		if line < 0 || line >= view.TotalHeight() {
 			return false
 		}
 
+		view.msgBufferLock.RLock()
 		message := view.msgBuffer[line]
 		var prevMessage messages.UIMessage
 		if y != 0 && line > 0 {
 			prevMessage = view.msgBuffer[line-1]
 		}
+		view.msgBufferLock.RUnlock()
 
 		usernameX := view.TimestampWidth + TimestampSenderGap
-		messageX := usernameX + view.widestSender + SenderMessageGap
+		messageX := usernameX + view.widestSender() + SenderMessageGap
 
 		if x >= messageX {
 			return view.handleMessageClick(message)
@@ -336,30 +385,59 @@ const PaddingAtTop = 5
 
 func (view *MessageView) AddScrollOffset(diff int) {
 	totalHeight := view.TotalHeight()
-	if diff >= 0 && view.ScrollOffset+diff >= totalHeight-view.height+PaddingAtTop {
+	height := view.Height()
-		view.ScrollOffset = totalHeight - view.height + PaddingAtTop
+	if diff >= 0 && view.ScrollOffset+diff >= totalHeight-height+PaddingAtTop {
+		view.ScrollOffset = totalHeight - height + PaddingAtTop
 	} else {
 		view.ScrollOffset += diff
 	}
 
-	if view.ScrollOffset > totalHeight-view.height+PaddingAtTop {
+	if view.ScrollOffset > totalHeight-height+PaddingAtTop {
-		view.ScrollOffset = totalHeight - view.height + PaddingAtTop
+		view.ScrollOffset = totalHeight - height + PaddingAtTop
 	}
 	if view.ScrollOffset < 0 {
 		view.ScrollOffset = 0
 	}
 }
 
+func (view *MessageView) setSize(width, height int) {
+	atomic.StoreUint32(&view._width, uint32(width))
+	atomic.StoreUint32(&view._height, uint32(height))
+}
+
+func (view *MessageView) updatePrevSize() {
+	atomic.StoreUint32(&view._prevWidth, atomic.LoadUint32(&view._width))
+	atomic.StoreUint32(&view._prevHeight, atomic.LoadUint32(&view._height))
+}
+
+func (view *MessageView) prevHeight() int {
+	return int(atomic.LoadUint32(&view._prevHeight))
+}
+
+func (view *MessageView) prevWidth() int {
+	return int(atomic.LoadUint32(&view._prevWidth))
+}
+
+func (view *MessageView) widestSender() int {
+	return int(atomic.LoadUint32(&view._widestSender))
+}
+
 func (view *MessageView) Height() int {
-	return view.height
+	return int(atomic.LoadUint32(&view._height))
+}
+
+func (view *MessageView) width() int {
+	return int(atomic.LoadUint32(&view._width))
 }
 
 func (view *MessageView) TotalHeight() int {
+	view.msgBufferLock.RLock()
+	defer view.msgBufferLock.RUnlock()
 	return len(view.msgBuffer)
 }
 
 func (view *MessageView) IsAtTop() bool {
-	return view.ScrollOffset >= len(view.msgBuffer)-view.height+PaddingAtTop
+	return view.ScrollOffset >= view.TotalHeight()-view.Height()+PaddingAtTop
 }
 
 const (
@@ -407,7 +485,7 @@ func (view *MessageView) getIndexOffset(screen mauview.Screen, height, messageX
 	indexOffset = view.TotalHeight() - view.ScrollOffset - height
 	if indexOffset <= -PaddingAtTop {
 		message := "Scroll up to load more messages."
-		if view.LoadingMessages {
+		if atomic.LoadInt32(&view.loadingMessages) == 1 {
 			message = "Loading more messages..."
 		}
 		widget.WriteLineSimpleColor(screen, message, messageX, 0, tcell.ColorGreen)
@@ -419,6 +497,7 @@ func (view *MessageView) CapturePlaintext(height int) string {
 	var buf strings.Builder
 	indexOffset := view.TotalHeight() - view.ScrollOffset - height
 	var prevMessage messages.UIMessage
+	view.msgBufferLock.RLock()
 	for line := 0; line < height; line++ {
 		index := indexOffset + line
 		if index < 0 {
@@ -438,27 +517,29 @@ func (view *MessageView) CapturePlaintext(height int) string {
 			prevMessage = message
 		}
 	}
+	view.msgBufferLock.RUnlock()
 	return buf.String()
 }
 
 func (view *MessageView) Draw(screen mauview.Screen) {
-	view.width, view.height = screen.Size()
+	view.setSize(screen.Size())
 	view.recalculateBuffers()
 
+	height := view.Height()
 	if view.TotalHeight() == 0 {
-		widget.WriteLineSimple(screen, "It's quite empty in here.", 0, view.height)
+		widget.WriteLineSimple(screen, "It's quite empty in here.", 0, height)
 		return
 	}
 
 	usernameX := view.TimestampWidth + TimestampSenderGap
-	messageX := usernameX + view.widestSender + SenderMessageGap
+	messageX := usernameX + view.widestSender() + SenderMessageGap
 
 	bareMode := view.config.Preferences.BareMessageView
 	if bareMode {
 		messageX = 0
 	}
 
-	indexOffset := view.getIndexOffset(screen, view.height, messageX)
+	indexOffset := view.getIndexOffset(screen, height, messageX)
 
 	viewStart := 0
 	if indexOffset < 0 {
@@ -466,13 +547,13 @@ func (view *MessageView) Draw(screen mauview.Screen) {
 	}
 
 	if !bareMode {
-		separatorX := usernameX + view.widestSender + SenderSeparatorGap
+		separatorX := usernameX + view.widestSender() + SenderSeparatorGap
-		scrollBarHeight, scrollBarPos := view.calculateScrollBar(view.height)
+		scrollBarHeight, scrollBarPos := view.calculateScrollBar(height)
 
-		for line := viewStart; line < view.height; line++ {
+		for line := viewStart; line < height; line++ {
 			showScrollbar := line-viewStart >= scrollBarPos-scrollBarHeight && line-viewStart < scrollBarPos
-			isTop := line == viewStart && view.ScrollOffset+view.height >= view.TotalHeight()
+			isTop := line == viewStart && view.ScrollOffset+height >= view.TotalHeight()
-			isBottom := line == view.height-1 && view.ScrollOffset == 0
+			isBottom := line == height-1 && view.ScrollOffset == 0
 
 			borderChar, borderStyle := getScrollbarStyle(showScrollbar, isTop, isBottom)
 
@@ -481,7 +562,8 @@ func (view *MessageView) Draw(screen mauview.Screen) {
 	}
 
 	var prevMsg messages.UIMessage
-	for line := viewStart; line < view.height && indexOffset+line < view.TotalHeight(); line++ {
+	view.msgBufferLock.RLock()
+	for line := viewStart; line < height && indexOffset+line < len(view.msgBuffer); line++ {
 		index := indexOffset + line
 
 		msg := view.msgBuffer[index]
@@ -493,7 +575,7 @@ func (view *MessageView) Draw(screen mauview.Screen) {
 			//if !bareMode && (prevMsg == nil || meta.Sender() != prevMsg.Sender()) {
 			widget.WriteLineColor(
 				screen, mauview.AlignRight, msg.Sender(),
-				usernameX, line, view.widestSender,
+				usernameX, line, view.widestSender(),
 				msg.SenderColor())
 			//}
 			prevMsg = msg
@@ -502,7 +584,8 @@ func (view *MessageView) Draw(screen mauview.Screen) {
 		for i := index - 1; i >= 0 && view.msgBuffer[i] == msg; i-- {
 			line--
 		}
-		msg.Draw(mauview.NewProxyScreen(screen, messageX, line, view.width-messageX, msg.Height()))
+		msg.Draw(mauview.NewProxyScreen(screen, messageX, line, view.width()-messageX, msg.Height()))
 		line += msg.Height() - 1
 	}
+	view.msgBufferLock.RUnlock()
 }

ui/room-list.go

@@ -20,6 +20,7 @@ import (
 	"math"
 	"regexp"
 	"strings"
+	"sync"
 
 	"maunium.net/go/mauview"
 	"maunium.net/go/tcell"
@@ -29,6 +30,8 @@ import (
 )
 
 type RoomList struct {
+	sync.RWMutex
+
 	parent *MainView
 
 	// The list of tags in display order.
@@ -71,6 +74,8 @@ func NewRoomList(parent *MainView) *RoomList {
 }
 
 func (list *RoomList) Contains(roomID string) bool {
+	list.RLock()
+	defer list.RUnlock()
 	for _, trl := range list.items {
 		for _, room := range trl.All() {
 			if room.ID == roomID {
@@ -88,8 +93,8 @@ func (list *RoomList) Add(room *rooms.Room) {
 	}
 }
 
-func (list *RoomList) CheckTag(tag string) {
+func (list *RoomList) checkTag(tag string) {
-	index := list.IndexTag(tag)
+	index := list.indexTag(tag)
 
 	trl, ok := list.items[tag]
 
@@ -107,6 +112,8 @@ func (list *RoomList) CheckTag(tag string) {
 }
 
 func (list *RoomList) AddToTag(tag rooms.RoomTag, room *rooms.Room) {
+	list.Lock()
+	defer list.Unlock()
 	trl, ok := list.items[tag.Tag]
 	if !ok {
 		list.items[tag.Tag] = NewTagRoomList(list, tag.Tag, NewDefaultOrderedRoom(room))
@@ -114,7 +121,7 @@ func (list *RoomList) AddToTag(tag rooms.RoomTag, room *rooms.Room) {
 	}
 
 	trl.Insert(tag.Order, room)
-	list.CheckTag(tag.Tag)
+	list.checkTag(tag.Tag)
 }
 
 func (list *RoomList) Remove(room *rooms.Room) {
@@ -124,6 +131,8 @@ func (list *RoomList) Remove(room *rooms.Room) {
 }
 
 func (list *RoomList) RemoveFromTag(tag string, room *rooms.Room) {
+	list.Lock()
+	defer list.Unlock()
 	trl, ok := list.items[tag]
 	if !ok {
 		return
@@ -158,10 +167,12 @@ func (list *RoomList) RemoveFromTag(tag string, room *rooms.Room) {
 			list.selectedTag = ""
 		}
 	}
-	list.CheckTag(tag)
+	list.checkTag(tag)
 }
 
 func (list *RoomList) Bump(room *rooms.Room) {
+	list.RLock()
+	defer list.RUnlock()
 	for _, tag := range room.Tags() {
 		trl, ok := list.items[tag.Tag]
 		if !ok {
@@ -172,6 +183,8 @@ func (list *RoomList) Bump(room *rooms.Room) {
 }
 
 func (list *RoomList) Clear() {
+	list.Lock()
+	defer list.Unlock()
 	list.items = make(map[string]*TagRoomList)
 	list.tags = []string{"m.favourite", "net.maunium.gomuks.fake.direct", "", "m.lowpriority"}
 	for _, tag := range list.tags {
@@ -220,6 +233,8 @@ func (list *RoomList) AddScrollOffset(offset int) {
 }
 
 func (list *RoomList) First() (string, *rooms.Room) {
+	list.RLock()
+	defer list.RUnlock()
 	for _, tag := range list.tags {
 		trl := list.items[tag]
 		if trl.HasVisibleRooms() {
@@ -230,6 +245,8 @@ func (list *RoomList) First() (string, *rooms.Room) {
 }
 
 func (list *RoomList) Last() (string, *rooms.Room) {
+	list.RLock()
+	defer list.RUnlock()
 	for tagIndex := len(list.tags) - 1; tagIndex >= 0; tagIndex-- {
 		tag := list.tags[tagIndex]
 		trl := list.items[tag]
@@ -240,7 +257,7 @@ func (list *RoomList) Last() (string, *rooms.Room) {
 	return "", nil
 }
 
-func (list *RoomList) IndexTag(tag string) int {
+func (list *RoomList) indexTag(tag string) int {
 	for index, entry := range list.tags {
 		if tag == entry {
 			return index
@@ -250,6 +267,8 @@ func (list *RoomList) IndexTag(tag string) int {
 }
 
 func (list *RoomList) Previous() (string, *rooms.Room) {
+	list.RLock()
+	defer list.RUnlock()
 	if len(list.items) == 0 {
 		return "", nil
 	} else if list.selected == nil {
@@ -266,7 +285,7 @@ func (list *RoomList) Previous() (string, *rooms.Room) {
 	}
 
 	if index == trl.Length()-1 {
-		tagIndex := list.IndexTag(list.selectedTag)
+		tagIndex := list.indexTag(list.selectedTag)
 		tagIndex--
 		for ; tagIndex >= 0; tagIndex-- {
 			prevTag := list.tags[tagIndex]
@@ -283,6 +302,8 @@ func (list *RoomList) Previous() (string, *rooms.Room) {
 }
 
 func (list *RoomList) Next() (string, *rooms.Room) {
+	list.RLock()
+	defer list.RUnlock()
 	if len(list.items) == 0 {
 		return "", nil
 	} else if list.selected == nil {
@@ -299,7 +320,7 @@ func (list *RoomList) Next() (string, *rooms.Room) {
 	}
 
 	if index == 0 {
-		tagIndex := list.IndexTag(list.selectedTag)
+		tagIndex := list.indexTag(list.selectedTag)
 		tagIndex++
 		for ; tagIndex < len(list.tags); tagIndex++ {
 			nextTag := list.tags[tagIndex]
@@ -325,6 +346,8 @@ func (list *RoomList) Next() (string, *rooms.Room) {
 //
 // TODO: Sorting. Now just finds first room with new messages.
 func (list *RoomList) NextWithActivity() (string, *rooms.Room) {
+	list.RLock()
+	defer list.RUnlock()
 	for tag, trl := range list.items {
 		for _, room := range trl.All() {
 			if room.HasNewMessages() {
@@ -337,7 +360,7 @@ func (list *RoomList) NextWithActivity() (string, *rooms.Room) {
 }
 
 func (list *RoomList) index(tag string, room *rooms.Room) int {
-	tagIndex := list.IndexTag(tag)
+	tagIndex := list.indexTag(tag)
 	if tagIndex == -1 {
 		return -1
 	}
@@ -358,6 +381,7 @@ func (list *RoomList) index(tag string, room *rooms.Room) int {
 	if tagIndex > 0 {
 		for i := 0; i < tagIndex; i++ {
 			prevTag := list.tags[i]
+
 			prevTRL := list.items[prevTag]
 			localIndex += prevTRL.RenderHeight()
 		}
@@ -367,9 +391,11 @@ func (list *RoomList) index(tag string, room *rooms.Room) int {
 }
 
 func (list *RoomList) ContentHeight() (height int) {
+	list.RLock()
 	for _, tag := range list.tags {
 		height += list.items[tag].RenderHeight()
 	}
+	list.RUnlock()
 	return
 }
 
@@ -410,6 +436,8 @@ func (list *RoomList) clickRoom(line, column int, mod bool) bool {
 	if line < 0 {
 		return false
 	}
+	list.RLock()
+	defer list.RUnlock()
 	for _, tag := range list.tags {
 		trl := list.items[tag]
 		if line--; line == -1 {
@@ -484,6 +512,7 @@ func (list *RoomList) Draw(screen mauview.Screen) {
 	y -= list.scrollOffset
 
 	// Draw the list items.
+	list.RLock()
 	for _, tag := range list.tags {
 		trl := list.items[tag]
 		tagDisplayName := list.GetTagDisplayName(tag)
@@ -501,4 +530,5 @@ func (list *RoomList) Draw(screen mauview.Screen) {
 			break
 		}
 	}
+	list.RUnlock()
 }

ui/tag-room-list.go

@@ -277,7 +277,7 @@ func (trl *TagRoomList) Draw(screen mauview.Screen) {
 	screen.SetCell(width-1, 0, tcell.StyleDefault, '▼')
 
 	y := 1
-	for i := trl.Length() - 1; i >= 0; i-- {
+	for i := len(items) - 1; i >= 0; i-- {
 		if y >= height {
 			return
 		}

ui/view-main.go

@@ -20,6 +20,8 @@ import (
 	"bufio"
 	"fmt"
 	"os"
+	"sync"
+	"sync/atomic"
 	"time"
 	"unicode"
 
@@ -42,6 +44,7 @@ type MainView struct {
 	roomView     *mauview.Box
 	currentRoom  *RoomView
 	rooms        map[string]*RoomView
+	roomsLock    sync.RWMutex
 	cmdProcessor *CommandProcessor
 	focused      mauview.Focusable
 
@@ -245,13 +248,17 @@ func (view *MainView) Blur() {
 }
 
 func (view *MainView) SwitchRoom(tag string, room *rooms.Room) {
+	view.switchRoom(tag, room, true)
+}
+
+func (view *MainView) switchRoom(tag string, room *rooms.Room, lock bool) {
 	if room == nil {
 		return
 	}
 
-	roomView := view.rooms[room.ID]
+	roomView, ok := view.getRoomView(room.ID, lock)
-	if roomView == nil {
+	if !ok {
-		debug.Print("Tried to switch to non-nil room with nil roomView!")
+		debug.Print("Tried to switch to room with nonexistent roomView!")
 		debug.Print(tag, room)
 		return
 	}
@@ -265,7 +272,7 @@ func (view *MainView) SwitchRoom(tag string, room *rooms.Room) {
 	}
 }
 
-func (view *MainView) addRoomPage(room *rooms.Room) {
+func (view *MainView) addRoomPage(room *rooms.Room) *RoomView {
 	if _, ok := view.rooms[room.ID]; !ok {
 		roomView := NewRoomView(view, room).
 			SetInputChangedFunc(view.InputChanged)
@@ -276,53 +283,73 @@ func (view *MainView) addRoomPage(room *rooms.Room) {
 		if len(roomView.MessageView().messages) == 0 {
 			go view.LoadHistory(room.ID)
 		}
+		return roomView
 	}
+	return nil
 }
 
 func (view *MainView) GetRoom(roomID string) ifc.RoomView {
-	room, ok := view.rooms[roomID]
+	room, ok := view.getRoomView(roomID, true)
 	if !ok {
-		view.AddRoom(view.matrix.GetRoom(roomID))
+		return view.addRoom(view.matrix.GetRoom(roomID))
-		room, ok := view.rooms[roomID]
-		if !ok {
-			return nil
 	}
 	return room
 }
-	return room
+
+func (view *MainView) getRoomView(roomID string, lock bool) (room *RoomView, ok bool) {
+	if lock {
+		view.roomsLock.RLock()
+		room, ok = view.rooms[roomID]
+		view.roomsLock.RUnlock()
+	} else {
+		room, ok = view.rooms[roomID]
+	}
+	return room, ok
 }
 
 func (view *MainView) AddRoom(room *rooms.Room) {
-	if view.roomList.Contains(room.ID) {
+	view.addRoom(room)
-		debug.Print("Add aborted (room exists)", room.ID, room.GetTitle())
-		return
-	}
-	debug.Print("Adding", room.ID, room.GetTitle())
-	view.roomList.Add(room)
-	view.addRoomPage(room)
-	if !view.roomList.HasSelected() {
-		view.SwitchRoom(view.roomList.First())
-	}
 }
 
 func (view *MainView) RemoveRoom(room *rooms.Room) {
-	roomView := view.GetRoom(room.ID)
+	view.roomsLock.Lock()
-	if roomView == nil {
+	_, ok := view.getRoomView(room.ID, false)
+	if !ok {
+		view.roomsLock.Unlock()
 		debug.Print("Remove aborted (not found)", room.ID, room.GetTitle())
 		return
 	}
 	debug.Print("Removing", room.ID, room.GetTitle())
 
 	view.roomList.Remove(room)
-	view.SwitchRoom(view.roomList.Selected())
+	t, r := view.roomList.Selected()
-
+	view.switchRoom(t, r, false)
 	delete(view.rooms, room.ID)
+	view.roomsLock.Unlock()
 
 	view.parent.Render()
 }
 
+func (view *MainView) addRoom(room *rooms.Room) *RoomView {
+	if view.roomList.Contains(room.ID) {
+		debug.Print("Add aborted (room exists)", room.ID, room.GetTitle())
+		return nil
+	}
+	debug.Print("Adding", room.ID, room.GetTitle())
+	view.roomList.Add(room)
+	view.roomsLock.Lock()
+	roomView := view.addRoomPage(room)
+	if !view.roomList.HasSelected() {
+		t, r := view.roomList.First()
+		view.switchRoom(t, r, false)
+	}
+	view.roomsLock.Unlock()
+	return roomView
+}
+
 func (view *MainView) SetRooms(rooms map[string]*rooms.Room) {
 	view.roomList.Clear()
+	view.roomsLock.Lock()
 	view.rooms = make(map[string]*RoomView)
 	for _, room := range rooms {
 		if room.HasLeft {
@@ -331,7 +358,9 @@ func (view *MainView) SetRooms(rooms map[string]*rooms.Room) {
 		view.roomList.Add(room)
 		view.addRoomPage(room)
 	}
-	view.SwitchRoom(view.roomList.First())
+	t, r := view.roomList.First()
+	view.switchRoom(t, r, false)
+	view.roomsLock.Unlock()
 }
 
 func (view *MainView) UpdateTags(room *rooms.Room) {
@@ -342,8 +371,8 @@ func (view *MainView) UpdateTags(room *rooms.Room) {
 	view.roomList.Add(room)
 }
 
-func (view *MainView) SetTyping(room string, users []string) {
+func (view *MainView) SetTyping(roomID string, users []string) {
-	roomView, ok := view.rooms[room]
+	roomView, ok := view.getRoomView(roomID, true)
 	if ok {
 		roomView.SetTyping(users)
 		view.parent.Render()
@@ -392,33 +421,27 @@ func (view *MainView) NotifyMessage(room *rooms.Room, message ifc.Message, shoul
 
 func (view *MainView) InitialSyncDone() {
 	view.roomList.Clear()
+	view.roomsLock.RLock()
 	for _, room := range view.rooms {
 		view.roomList.Add(room.Room)
 		room.UpdateUserList()
 	}
+	view.roomsLock.RUnlock()
 }
 
-func (view *MainView) LoadHistory(room string) {
+func (view *MainView) LoadHistory(roomID string) {
 	defer debug.Recover()
-	roomView := view.rooms[room]
+	roomView, ok := view.getRoomView(roomID, true)
-	msgView := roomView.MessageView()
+	if !ok {
-
-	batch := roomView.Room.PrevBatch
-	lockTime := time.Now().Unix() + 1
-
-	roomView.Room.LockHistory()
-	msgView.LoadingMessages = true
-	defer func() {
-		roomView.Room.UnlockHistory()
-		msgView.LoadingMessages = false
-	}()
-
-	// There's no clean way to try to lock a mutex, so we just check if we still
-	// want to continue after we get the lock. This function should always be ran
-	// in a goroutine, so the blocking doesn't matter.
-	if time.Now().Unix() >= lockTime || batch != roomView.Room.PrevBatch {
 		return
 	}
+	msgView := roomView.MessageView()
+
+	if !atomic.CompareAndSwapInt32(&msgView.loadingMessages, 0, 1) {
+		// Locked
+		return
+	}
+	defer atomic.StoreInt32(&msgView.loadingMessages, 0)
 
 	history, err := view.matrix.GetHistory(roomView.Room, 50)
 	if err != nil {