HomeView caches thread models

// FREEBIE

Signal/src/Models/ThreadModel.swift

@@ -20,67 +20,6 @@ public class ThreadModel: NSObject {
 
     let lastMessageText: String?
 
-//    func attributedSnippet(blockedPhoneNumberSet: Set<String>) {
-//        let isBlocked: Bool = {
-//            guard let contactIdentifier = self.contactIdentifier else {
-//                return false
-//            }
-//            assert(isContactThread)
-//            return blockedPhoneNumberSet.contains(self.contactIdentifier)
-//        }()
-//            
-//        
-//            
-////            BOOL hasUnreadMessages = thread.hasUnreadMessages;
-//        
-////            NSMutableAttributedString *snippetText = [NSMutableAttributedString new];
-//        var snippetText = NSMutableAttributedString()
-//        if isBlocked {
-//            // If thread is blocked, don't show a snippet or mute status.
-//            let append = NSAttributedString(string: NSLocalizedString("HOME_VIEW_BLOCKED_CONTACT_CONVERSATION",
-//                                                                      comment: "A label for conversations with blocked users."),
-//                attributes: <#T##[String : Any]?#>)
-//            
-////            if (isBlocked) {
-////                // If thread is blocked, don't show a snippet or mute status.
-////                [snippetText
-////                    appendAttributedString:[[NSAttributedString alloc]
-////                    initWithString:NSLocalizedString(@"HOME_VIEW_BLOCKED_CONTACT_CONVERSATION",
-////                    @"A label for conversations with blocked users.")
-////                    attributes:@{
-////                    NSFontAttributeName : self.snippetFont.ows_mediumWeight,
-////                    NSForegroundColorAttributeName : [UIColor ows_blackColor],
-////                    }]];
-////            } else {
-////                if ([thread isMuted]) {
-////                    [snippetText appendAttributedString:[[NSAttributedString alloc]
-////                        initWithString:@"\ue067  "
-////                        attributes:@{
-////                        NSFontAttributeName : [UIFont ows_elegantIconsFont:9.f],
-////                        NSForegroundColorAttributeName : (hasUnreadMessages
-////                        ? [UIColor colorWithWhite:0.1f alpha:1.f]
-////                        : [UIColor lightGrayColor]),
-////                        }]];
-////                }
-////                NSString *displayableText = thread.lastMessageText;
-////                if (displayableText) {
-////                    [snippetText appendAttributedString:[[NSAttributedString alloc]
-////                        initWithString:displayableText
-////                        attributes:@{
-////                        NSFontAttributeName :
-////                        (hasUnreadMessages ? self.snippetFont.ows_mediumWeight
-////                        : self.snippetFont),
-////                        NSForegroundColorAttributeName :
-////                        (hasUnreadMessages ? [UIColor ows_blackColor]
-////                        : [UIColor lightGrayColor]),
-////                        }]];
-////                }
-////            }
-////
-////            return snippetText;
-//        }
-//    }
-
     init(thread: TSThread, transaction: YapDatabaseReadTransaction) {
         self.threadRecord = thread
         self.lastMessageDate = thread.lastMessageDate()

Signal/src/ViewControllers/HomeView/HomeViewController.m

@@ -47,7 +47,7 @@ typedef NS_ENUM(NSInteger, CellState) { kArchiveState, kInboxState };
 @property (nonatomic) UISegmentedControl *segmentedControl;
 @property (nonatomic) id previewingContext;
 @property (nonatomic) NSSet<NSString *> *blockedPhoneNumberSet;
-
+@property (nonatomic, readonly) NSCache<NSString *, ThreadModel *> *threadModelCache;
 @property (nonatomic) BOOL isViewVisible;
 @property (nonatomic) BOOL isAppInBackground;
 @property (nonatomic) BOOL shouldObserveDBModifications;
@@ -108,6 +108,7 @@ typedef NS_ENUM(NSInteger, CellState) { kArchiveState, kInboxState };
     _messageSender = [Environment current].messageSender;
     _blockingManager = [OWSBlockingManager sharedManager];
     _blockedPhoneNumberSet = [NSSet setWithArray:[_blockingManager blockedPhoneNumbers]];
+    _threadModelCache = [NSCache new];
 
     // Ensure ExperienceUpgradeFinder has been initialized.
     [ExperienceUpgradeFinder sharedManager];
@@ -595,17 +596,29 @@ typedef NS_ENUM(NSInteger, CellState) { kArchiveState, kInboxState };
     return (NSInteger)[self.threadMappings numberOfItemsInSection:(NSUInteger)section];
 }
 
+- (ThreadModel *)threadModelForIndexPath:(NSIndexPath *)indexPath
+{
+    TSThread *threadRecord = [self threadForIndexPath:indexPath];
+
+    ThreadModel *_Nullable cachedThreadModel = [self.threadModelCache objectForKey:threadRecord.uniqueId];
+    if (cachedThreadModel) {
+        return cachedThreadModel;
+    }
+
+    __block ThreadModel *_Nullable newThreadModel;
+    [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
+        newThreadModel = [[ThreadModel alloc] initWithThread:threadRecord transaction:transaction];
+    }];
+    [self.threadModelCache setObject:newThreadModel forKey:threadRecord.uniqueId];
+    return newThreadModel;
+}
+
 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
 {
     HomeViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:HomeViewCell.cellReuseIdentifier];
     OWSAssert(cell);
 
-    TSThread *threadRecord = [self threadForIndexPath:indexPath];
-    __block ThreadModel *thread;
-    [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
-        thread = [[ThreadModel alloc] initWithThread:threadRecord transaction:transaction];
-    }];
-
+    ThreadModel *thread = [self threadModelForIndexPath:indexPath];
     [cell configureWithThread:thread
               contactsManager:self.contactsManager
         blockedPhoneNumberSet:self.blockedPhoneNumberSet];
@@ -1016,6 +1029,10 @@ typedef NS_ENUM(NSInteger, CellState) { kArchiveState, kInboxState };
     }
 
     for (YapDatabaseViewRowChange *rowChange in rowChanges) {
+        NSString *key = rowChange.collectionKey.key;
+        OWSAssert(key);
+        [self.threadModelCache removeObjectForKey:key];
+
         switch (rowChange.type) {
             case YapDatabaseViewChangeDelete: {
                 [self.tableView deleteRowsAtIndexPaths:@[ rowChange.indexPath ]

SignalServiceKit/src/Messages/Interactions/TSInteraction.m

@@ -127,9 +127,10 @@ NS_ASSUME_NONNULL_BEGIN
     return OWSInteractionType_Unknown;
 }
 
-- (NSString *)description {
-    OWSFail(@"Abstract Method");
-    return @"Interaction description";
+- (NSString *)description
+{
+    return [NSString
+        stringWithFormat:@"%@ in thread: %@ timestamp: %tu", [super description], self.uniqueThreadId, self.timestamp];
 }
 
 - (void)saveWithTransaction:(YapDatabaseReadWriteTransaction *)transaction {

SignalServiceKit/src/Messages/Interactions/TSMessage.m

@@ -265,13 +265,6 @@ static const NSUInteger OWSMessageSchemaVersion = 4;
     }
 }
 
-- (NSString *)description
-{
-    // TODO verify this isn't exposed in the UI
-    OWSFail(@"%@ in %s verify this isn't being used anywhere except logging.", self.logTag, __PRETTY_FUNCTION__);
-    return [super description];
-}
-
 - (void)removeWithTransaction:(YapDatabaseReadWriteTransaction *)transaction
 {
     [super removeWithTransaction:transaction];

SignalServiceKit/src/Storage/TSYapDatabaseObject.m

@@ -109,8 +109,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (YapDatabaseConnection *)dbReadConnection
 {
-    OWSAssert(![NSThread isMainThread]);
-    
+    //    OWSAssert(![NSThread isMainThread]);
+
     // We use TSYapDatabaseObject's dbReadWriteConnection (not OWSPrimaryStorage's
     // dbReadConnection) for consistency, since we tend to [TSYapDatabaseObject
     // save] and want to write to the same connection we read from.  To get true
@@ -121,7 +121,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 + (YapDatabaseConnection *)dbReadWriteConnection
 {
-    OWSAssert(![NSThread isMainThread]);
+    //    OWSAssert(![NSThread isMainThread]);
 
     // Use a dedicated connection for model reads & writes.
     static YapDatabaseConnection *dbReadWriteConnection = nil;