Perf: Insert outgoing message into conversation before save completes.

This was a huge savings - e.g. 50-70% of the time between tapping send and
rendering the message takes place in the save/postWriteTransaction blocks

Signal/src/ViewControllers/ConversationView/ConversationViewController.m

@@ -3887,13 +3887,14 @@ typedef enum : NSUInteger {
                                                   inThread:self.thread
                                           quotedReplyModel:self.inputToolbar.quotedReply];
     } else {
-        [self.editingDatabaseConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
+        [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
             message = [ThreadUtil enqueueMessageWithText:text
                                                 inThread:self.thread
                                         quotedReplyModel:self.inputToolbar.quotedReply
                                              transaction:transaction];
         }];
     }
+    [self.conversationViewModel appendUnsavedOutgoingMessage:message];
 
     [self messageWasSent:message];
 

Signal/src/ViewControllers/ConversationView/ConversationViewModel.h

@@ -7,6 +7,7 @@ NS_ASSUME_NONNULL_BEGIN
 @class ConversationStyle;
 @class ConversationViewModel;
 @class OWSQuotedReplyModel;
+@class TSOutgoingMessage;
 @class TSThread;
 @class ThreadDynamicInteractions;
 
@@ -101,6 +102,7 @@ typedef NS_ENUM(NSUInteger, ConversationUpdateItemType) {
 - (BOOL)canLoadMoreItems;
 
 - (nullable NSIndexPath *)ensureLoadWindowContainsQuotedReply:(OWSQuotedReplyModel *)quotedReply;
+- (void)appendUnsavedOutgoingMessage:(TSOutgoingMessage *)outgoingMessage;
 
 @end
 

Signal/src/ViewControllers/ConversationView/ConversationViewModel.m

@@ -12,6 +12,7 @@
 #import <SignalMessaging/OWSContactOffersInteraction.h>
 #import <SignalMessaging/OWSContactsManager.h>
 #import <SignalMessaging/OWSUnreadIndicator.h>
+#import <SignalMessaging/SignalMessaging-Swift.h>
 #import <SignalMessaging/ThreadUtil.h>
 #import <SignalServiceKit/OWSBlockingManager.h>
 #import <SignalServiceKit/OWSPrimaryStorage.h>
@@ -1491,6 +1492,33 @@ static const int kYapDatabaseRangeMinLength = 0;
     return !hasError;
 }
 
+- (void)appendUnsavedOutgoingMessage:(TSOutgoingMessage *)outgoingMessage
+{
+//    id<ConversationViewItem> viewItem = [[OutgoingUnsavedConversationViewItem alloc] initWithOutgoingMessage:outgoingMessage];
+
+    __block ConversationInteractionViewItem *viewItem;
+    [self.uiDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction * _Nonnull transaction) {
+        viewItem =
+            [[ConversationInteractionViewItem alloc] initWithInteraction:outgoingMessage
+                                                       isGroupThread:self.thread.isGroupThread
+                                                         transaction:transaction
+                                                   conversationStyle:self.delegate.conversationStyle];
+    }];
+
+    ConversationUpdateItem *updateItem = [[ConversationUpdateItem alloc] initWithUpdateItemType:ConversationUpdateItemType_Insert
+                                                                                       oldIndex:0
+                                                                                       newIndex:self.viewItems.count
+                                                                                       viewItem:viewItem];
+
+    NSMutableArray<id <ConversationViewItem>> *viewItems = [self.viewItems mutableCopy];
+    [viewItems addObject:viewItem];
+    self.viewItems = viewItems;
+    ConversationUpdate *conversationUpdate = [[ConversationUpdate alloc] initWithConversationUpdateType:ConversationUpdateType_Diff
+                                                                                            updateItems:@[updateItem]
+                                                                                   shouldAnimateUpdates:NO];
+    [self.delegate conversationViewModelDidUpdate:conversationUpdate];
+}
+
 // Whenever an interaction is modified, we need to reload it from the DB
 // and update the corresponding view item.
 - (void)reloadInteractionForViewItem:(id<ConversationViewItem>)viewItem

SignalMessaging/utils/ThreadUtil.h

@@ -47,7 +47,7 @@ NS_ASSUME_NONNULL_BEGIN
 + (TSOutgoingMessage *)enqueueMessageWithText:(NSString *)text
                                      inThread:(TSThread *)thread
                              quotedReplyModel:(nullable OWSQuotedReplyModel *)quotedReplyModel
-                                  transaction:(YapDatabaseReadWriteTransaction *)transaction;
+                                  transaction:(YapDatabaseReadTransaction *)transaction;
 
 + (TSOutgoingMessage *)enqueueMessageWithAttachment:(SignalAttachment *)attachment
                                            inThread:(TSThread *)thread

SignalMessaging/utils/ThreadUtil.m

@@ -68,7 +68,7 @@ NS_ASSUME_NONNULL_BEGIN
 + (TSOutgoingMessage *)enqueueMessageWithText:(NSString *)text
                                      inThread:(TSThread *)thread
                              quotedReplyModel:(nullable OWSQuotedReplyModel *)quotedReplyModel
-                                  transaction:(YapDatabaseReadWriteTransaction *)transaction
+                                  transaction:(YapDatabaseReadTransaction *)transaction
 {
     OWSDisappearingMessagesConfiguration *configuration =
         [OWSDisappearingMessagesConfiguration fetchObjectWithUniqueID:thread.uniqueId transaction:transaction];
@@ -82,9 +82,13 @@ NS_ASSUME_NONNULL_BEGIN
                                   expiresInSeconds:expiresInSeconds
                                      quotedMessage:[quotedReplyModel buildQuotedMessageForSending]];
 
-    [message saveWithTransaction:transaction];
-
-    [self.messageSenderJobQueue addMessage:message transaction:transaction];
+    [BenchManager benchWithTitle:@"Saving outgoing message" block:^{
+        // To avoid blocking the send flow, we disapatch an async write from within this read transaction
+        [self.dbConnection asyncReadWriteWithBlock:^(YapDatabaseReadWriteTransaction * _Nonnull writeTransaction) {
+            [message saveWithTransaction:writeTransaction];
+            [self.messageSenderJobQueue addMessage:message transaction:writeTransaction];
+        }];
+    }];
 
     return message;
 }

SignalServiceKit/src/Network/MessageSenderJobQueue.swift

@@ -38,6 +38,7 @@ public class MessageSenderJobQueue: NSObject, JobQueue {
 
     @objc(addMessage:transaction:)
     public func add(message: TSOutgoingMessage, transaction: YapDatabaseReadWriteTransaction) {
+        message.save(with: transaction)
         self.add(message: message, removeMessageAfterSending: false, transaction: transaction)
     }