Respond to CR.

// FREEBIE

Signal/src/ViewControllers/ConversationView/MessagesViewController.m

@@ -332,8 +332,6 @@ typedef enum : NSUInteger {
     _composeOnOpen = keyboardOnViewAppearing;
     _callOnOpen = callOnViewAppearing;
 
-    [self.uiDatabaseConnection beginLongLivedReadTransaction];
-
     // We need to create the "unread indicator" before we mark
     // all messages as read.
     [self ensureDynamicInteractions];
@@ -540,6 +538,8 @@ typedef enum : NSUInteger {
 
 - (void)viewWillAppear:(BOOL)animated
 {
+    DDLogDebug(@"%@ viewWillAppear", self.tag);
+
     // We need to update the dynamic interactions before we do any layout.
     [self ensureDynamicInteractions];
 
@@ -990,6 +990,8 @@ typedef enum : NSUInteger {
 
 - (void)viewWillDisappear:(BOOL)animated
 {
+    DDLogDebug(@"%@ viewWillDisappear", self.tag);
+
     [super viewWillDisappear:animated];
     [self toggleObservers:NO];
 
@@ -2221,10 +2223,6 @@ typedef enum : NSUInteger {
     // while updating the range and the dynamic interactions.
     [[NSNotificationCenter defaultCenter] removeObserver:self name:YapDatabaseModifiedNotification object:nil];
 
-    // We need to `beginLongLivedReadTransaction` before we update our
-    // mapping in order to jump to the most recent commit.
-    [self.uiDatabaseConnection beginLongLivedReadTransaction];
-
     // We need to update the dynamic interactions after loading earlier messages,
     // since the unseen indicator may need to move or change.
     [self ensureDynamicInteractions];
@@ -2702,8 +2700,7 @@ typedef enum : NSUInteger {
         [ThreadUtil ensureDynamicInteractionsForThread:self.thread
                                        contactsManager:self.contactsManager
                                        blockingManager:self.blockingManager
-                                      readDBConnection:self.uiDatabaseConnection
+                                          dbConnection:self.editingDatabaseConnection
-                                     writeDBConnection:self.editingDatabaseConnection
                            hideUnreadMessagesIndicator:self.hasClearedUnreadMessagesIndicator
                        firstUnseenInteractionTimestamp:self.dynamicInteractions.firstUnseenInteractionTimestamp
                                           maxRangeSize:maxRangeSize];

Signal/src/util/ThreadUtil.h

@@ -83,8 +83,7 @@ NS_ASSUME_NONNULL_BEGIN
 + (ThreadDynamicInteractions *)ensureDynamicInteractionsForThread:(TSThread *)thread
                                                   contactsManager:(OWSContactsManager *)contactsManager
                                                   blockingManager:(OWSBlockingManager *)blockingManager
-                                                 readDBConnection:(YapDatabaseConnection *)readDBConnection
+                                                     dbConnection:(YapDatabaseConnection *)dbConnection
-                                                writeDBConnection:(YapDatabaseConnection *)writeDBConnection
                                       hideUnreadMessagesIndicator:(BOOL)hideUnreadMessagesIndicator
                                   firstUnseenInteractionTimestamp:(nullable NSNumber *)firstUnseenInteractionTimestamp
                                                      maxRangeSize:(int)maxRangeSize;

Signal/src/util/ThreadUtil.m

@@ -116,16 +116,14 @@ NS_ASSUME_NONNULL_BEGIN
 + (ThreadDynamicInteractions *)ensureDynamicInteractionsForThread:(TSThread *)thread
                                                   contactsManager:(OWSContactsManager *)contactsManager
                                                   blockingManager:(OWSBlockingManager *)blockingManager
-                                                 readDBConnection:(YapDatabaseConnection *)readDBConnection
+                                                     dbConnection:(YapDatabaseConnection *)dbConnection
-                                                writeDBConnection:(YapDatabaseConnection *)writeDBConnection
                                       hideUnreadMessagesIndicator:(BOOL)hideUnreadMessagesIndicator
                                   firstUnseenInteractionTimestamp:
                                       (nullable NSNumber *)firstUnseenInteractionTimestampParameter
                                                      maxRangeSize:(int)maxRangeSize
 {
     OWSAssert(thread);
-    OWSAssert(readDBConnection);
+    OWSAssert(dbConnection);
-    OWSAssert(writeDBConnection);
     OWSAssert(contactsManager);
     OWSAssert(blockingManager);
     OWSAssert(maxRangeSize > 0);
@@ -135,23 +133,15 @@ NS_ASSUME_NONNULL_BEGIN
 
     ThreadDynamicInteractions *result = [ThreadDynamicInteractions new];
 
-    const int kMaxBlockOfferOutgoingMessageCount = 10;
+    [dbConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
-
+        const int kMaxBlockOfferOutgoingMessageCount = 10;
-    __block OWSAddToContactsOfferMessage *existingAddToContactsOffer = nil;
-    __block OWSUnknownContactBlockOfferMessage *existingBlockOffer = nil;
-    __block TSUnreadIndicatorInteraction *existingUnreadIndicator = nil;
-    NSMutableArray<TSInvalidIdentityKeyErrorMessage *> *blockingSafetyNumberChanges = [NSMutableArray new];
-    NSMutableArray<TSInteraction *> *nonBlockingSafetyNumberChanges = [NSMutableArray new];
-    __block TSMessage *firstMessage = nil;
-    __block NSUInteger outgoingMessageCount;
-    __block NSUInteger threadMessageCount;
-    __block long visibleUnseenMessageCount = 0;
-    __block TSInteraction *interactionAfterUnreadIndicator = nil;
-    __block NSUInteger missingUnseenSafetyNumberChangeCount = 0;
-
-    [readDBConnection readWithBlock:^(YapDatabaseReadTransaction *transaction) {
 
         // Find any "dynamic" interactions and safety number changes.
+        __block OWSAddToContactsOfferMessage *existingAddToContactsOffer = nil;
+        __block OWSUnknownContactBlockOfferMessage *existingBlockOffer = nil;
+        __block TSUnreadIndicatorInteraction *existingUnreadIndicator = nil;
+        NSMutableArray<TSInvalidIdentityKeyErrorMessage *> *blockingSafetyNumberChanges = [NSMutableArray new];
+        NSMutableArray<TSInteraction *> *nonBlockingSafetyNumberChanges = [NSMutableArray new];
         // We use different views for performance reasons.
         [[TSDatabaseView threadSpecialMessagesDatabaseView:transaction]
             enumerateRowsInGroup:thread.uniqueId
@@ -196,6 +186,7 @@ NS_ASSUME_NONNULL_BEGIN
             }
         }
 
+        __block TSMessage *firstMessage = nil;
         [[transaction ext:TSMessageDatabaseViewExtensionName]
             enumerateRowsInGroup:thread.uniqueId
                       usingBlock:^(
@@ -210,9 +201,9 @@ NS_ASSUME_NONNULL_BEGIN
                           }
                       }];
 
-        outgoingMessageCount =
+        NSUInteger outgoingMessageCount =
             [[TSDatabaseView threadOutgoingMessageDatabaseView:transaction] numberOfItemsInGroup:thread.uniqueId];
-        threadMessageCount =
+        NSUInteger threadMessageCount =
             [[transaction ext:TSMessageDatabaseViewExtensionName] numberOfItemsInGroup:thread.uniqueId];
 
         // Enumerate in reverse to count the number of messages
@@ -221,6 +212,9 @@ NS_ASSUME_NONNULL_BEGIN
         // the messages view the position of the unread indicator,
         // so that it can widen its "load window" to always show
         // the unread indicator.
+        __block long visibleUnseenMessageCount = 0;
+        __block TSInteraction *interactionAfterUnreadIndicator = nil;
+        NSUInteger missingUnseenSafetyNumberChangeCount = 0;
         if (result.firstUnseenInteractionTimestamp != nil) {
             [[transaction ext:TSMessageDatabaseViewExtensionName]
                 enumerateRowsInGroup:thread.uniqueId
@@ -294,9 +288,7 @@ NS_ASSUME_NONNULL_BEGIN
             result.unreadIndicatorPosition = @(visibleUnseenMessageCount);
         }
         OWSAssert((result.firstUnseenInteractionTimestamp != nil) == (result.unreadIndicatorPosition != nil));
-    }];
 
-    [writeDBConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *transaction) {
         BOOL shouldHaveBlockOffer = YES;
         BOOL shouldHaveAddToContactsOffer = YES;