split: refactor to prevent stuck splits

Refactor split logic (again...) to prevent stuck splits. Use callback
from msgstore.Select to tell the split which message to display. This
keeps the account from having to track displayed messages, which
prevents race conditions in certain situations.

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Tested-by: Bence Ferdinandy <bence@ferdinandy.com>

2 files changed, 17 insertions, 3 deletions

diff --git a/lib/messageview.go b/lib/messageview.go
index d7ff1908..d0754cc1 100644
--- a/lib/messageview.go
+++ b/lib/messageview.go
@@ -72,6 +72,12 @@ func NewMessageStoreView(messageInfo *models.MessageInfo, setSeen bool,
 	store *MessageStore, pgp crypto.Provider, decryptKeys openpgp.PromptFunction,
 	cb func(MessageView, error),
 ) {
+	if messageInfo == nil {
+		// Call nils to the callback, the split view will use this to
+		// display an empty view
+		cb(nil, nil)
+		return
+	}
 	msv := &MessageStoreView{
 		messageInfo, store,
 		nil, nil, messageInfo.BodyStructure,
diff --git a/lib/msgstore.go b/lib/msgstore.go
index c02d8f4d..1a56b2c8 100644
--- a/lib/msgstore.go
+++ b/lib/msgstore.go
@@ -69,6 +69,7 @@ type MessageStore struct {
 	threadsMutex sync.Mutex
 
 	iterFactory iterator.Factory
+	onSelect    func(*models.MessageInfo)
 }
 
 const MagicUid = 0xFFFFFFFF
@@ -79,7 +80,7 @@ func NewMessageStore(worker *types.Worker,
 	thread bool, clientThreads bool, clientThreadsDelay time.Duration,
 	reverseOrder bool, reverseThreadOrder bool, sortThreadSiblings bool,
 	triggerNewEmail func(*models.MessageInfo),
-	triggerDirectoryChange func(),
+	triggerDirectoryChange func(), onSelect func(*models.MessageInfo),
 ) *MessageStore {
 	if !dirInfo.Caps.Thread {
 		clientThreads = true
@@ -116,6 +117,7 @@ func NewMessageStore(worker *types.Worker,
 		threadBuilderDelay: clientThreadsDelay,
 
 		iterFactory: iterator.NewFactory(reverseOrder),
+		onSelect:    onSelect,
 	}
 }
 
@@ -257,6 +259,9 @@ func (store *MessageStore) Update(msg types.WorkerMessage) {
 			merge(existing, msg.Info)
 		} else if msg.Info.Envelope != nil {
 			store.Messages[msg.Info.Uid] = msg.Info
+			if store.selectedUid == msg.Info.Uid {
+				store.onSelect(msg.Info)
+			}
 		}
 		if msg.NeedsFlags {
 			store.Lock()
@@ -597,7 +602,7 @@ func (store *MessageStore) Selected() *models.MessageInfo {
 func (store *MessageStore) SelectedUid() uint32 {
 	if store.selectedUid == MagicUid && len(store.Uids()) > 0 {
 		iter := store.UidsIterator()
-		store.selectedUid = store.Uids()[iter.StartIndex()]
+		store.Select(store.Uids()[iter.StartIndex()])
 	}
 	return store.selectedUid
 }
@@ -612,6 +617,9 @@ func (store *MessageStore) Select(uid uint32) {
 	if store.marker != nil {
 		store.marker.UpdateVisualMark()
 	}
+	if store.onSelect != nil {
+		store.onSelect(store.Selected())
+	}
 }
 
 func (store *MessageStore) NextPrev(delta int) {
@@ -639,7 +647,7 @@ func (store *MessageStore) NextPrev(delta int) {
 		store.threadsMutex.Lock()
 		store.threadCallback = func() {
 			if uids := store.Uids(); len(uids) > newIdx {
-				store.selectedUid = uids[newIdx]
+				store.Select(uids[newIdx])
 			}
 		}
 		store.threadsMutex.Unlock()