fix(communities): ensure archive import is only cancelled if not already marked as such

There were cases where this caused a crash, as handling magnetlinks would try to close
an already closed tasked channel

See https://github.com/status-im/status-desktop/issues/8996 for more information.

This commit extends the task struct such that it can be marked as cancelled and safely
read and written by multiple go routines.

protocol/communities/manager.go

@@ -61,8 +61,23 @@ type Manager struct {
 }
 
 type HistoryArchiveDownloadTask struct {
-	Cancel chan struct{}
-	Waiter sync.WaitGroup
+	CancelChan chan struct{}
+	Waiter     sync.WaitGroup
+	m          sync.RWMutex
+	Cancelled  bool
+}
+
+func (t *HistoryArchiveDownloadTask) IsCancelled() bool {
+	t.m.RLock()
+	defer t.m.RUnlock()
+	return t.Cancelled
+}
+
+func (t *HistoryArchiveDownloadTask) Cancel() {
+	t.m.Lock()
+	defer t.m.Unlock()
+	t.Cancelled = true
+	close(t.CancelChan)
 }
 
 func NewManager(identity *ecdsa.PrivateKey, db *sql.DB, encryptor *encryption.Protocol, logger *zap.Logger, verifier *ens.Verifier, transport *transport.Transport, torrentConfig *params.TorrentConfig) (*Manager, error) {

protocol/messenger_communities.go

@@ -1999,8 +1999,9 @@ func (m *Messenger) resumeHistoryArchivesImport(communityID types.HexBytes) erro
 
 	// Create new task
 	task := &communities.HistoryArchiveDownloadTask{
-		Cancel: make(chan struct{}),
-		Waiter: *new(sync.WaitGroup),
+		CancelChan: make(chan struct{}),
+		Waiter:     *new(sync.WaitGroup),
+		Cancelled:  false,
 	}
 
 	m.communitiesManager.AddHistoryArchiveDownloadTask(communityID.String(), task)
@@ -2009,11 +2010,8 @@ func (m *Messenger) resumeHistoryArchivesImport(communityID types.HexBytes) erro
 	task.Waiter.Add(1)
 
 	go func() {
-		defer func() {
-			task.Waiter.Done()
-			m.communitiesManager.DeleteHistoryArchiveDownloadTask(communityID.String())
-		}()
-		err := m.importHistoryArchives(communityID, task.Cancel)
+		defer task.Waiter.Done()
+		err := m.importHistoryArchives(communityID, task.CancelChan)
 		if err != nil {
 			m.communitiesManager.LogStdout("failed to import history archives", zap.Error(err))
 		}

protocol/messenger_handler.go

@@ -941,30 +941,28 @@ func (m *Messenger) HandleHistoryArchiveMagnetlinkMessage(state *ReceivedMessage
 			go func(currentTask *communities.HistoryArchiveDownloadTask, communityID types.HexBytes) {
 
 				// Cancel ongoing download/import task
-				if currentTask != nil {
-					close(currentTask.Cancel)
+				if currentTask != nil && !currentTask.IsCancelled() {
+					currentTask.Cancel()
 					currentTask.Waiter.Wait()
 				}
 
 				// Create new task
 				task := &communities.HistoryArchiveDownloadTask{
-					Cancel: make(chan struct{}),
-					Waiter: *new(sync.WaitGroup),
+					CancelChan: make(chan struct{}),
+					Waiter:     *new(sync.WaitGroup),
+					Cancelled:  false,
 				}
 
 				m.communitiesManager.AddHistoryArchiveDownloadTask(communityID.String(), task)
 
 				// this wait groups tracks the ongoing task for a particular community
 				task.Waiter.Add(1)
-				defer func() {
-					task.Waiter.Done()
-					m.communitiesManager.DeleteHistoryArchiveDownloadTask(communityID.String())
-				}()
+				defer task.Waiter.Done()
 
 				// this wait groups tracks all ongoing tasks across communities
 				m.downloadHistoryArchiveTasksWaitGroup.Add(1)
 				defer m.downloadHistoryArchiveTasksWaitGroup.Done()
-				m.downloadAndImportHistoryArchives(communityID, magnetlink, task.Cancel)
+				m.downloadAndImportHistoryArchives(communityID, magnetlink, task.CancelChan)
 			}(currentTask, id)
 
 			return m.communitiesManager.UpdateMagnetlinkMessageClock(id, clock)
@@ -1186,14 +1184,15 @@ func (m *Messenger) HandleCommunityRequestToJoinResponse(state *ReceivedMessageS
 				go func(currentTask *communities.HistoryArchiveDownloadTask) {
 
 					// Cancel ongoing download/import task
-					if currentTask != nil {
-						close(currentTask.Cancel)
+					if currentTask != nil && !currentTask.IsCancelled() {
+						currentTask.Cancel()
 						currentTask.Waiter.Wait()
 					}
 
 					task := &communities.HistoryArchiveDownloadTask{
-						Cancel: make(chan struct{}),
-						Waiter: *new(sync.WaitGroup),
+						CancelChan: make(chan struct{}),
+						Waiter:     *new(sync.WaitGroup),
+						Cancelled:  false,
 					}
 					m.communitiesManager.AddHistoryArchiveDownloadTask(community.IDString(), task)
 
@@ -1203,7 +1202,7 @@ func (m *Messenger) HandleCommunityRequestToJoinResponse(state *ReceivedMessageS
 					m.downloadHistoryArchiveTasksWaitGroup.Add(1)
 					defer m.downloadHistoryArchiveTasksWaitGroup.Done()
 
-					m.downloadAndImportHistoryArchives(community.ID(), magnetlink, task.Cancel)
+					m.downloadAndImportHistoryArchives(community.ID(), magnetlink, task.CancelChan)
 				}(currentTask)
 
 				clock := requestToJoinResponseProto.Community.ArchiveMagnetlinkClock