No write transaction needed for syncing colors

// FREEBIE

SignalMessaging/contacts/OWSContactsSyncing.m

@@ -126,7 +126,7 @@ NSString *const kOWSPrimaryStorageOWSContactsSyncingLastMessageKey
 
         __block NSData *messageData;
         __block NSData *lastMessageData;
-        [self.editingDatabaseConnection readWriteWithBlock:^(YapDatabaseReadWriteTransaction *_Nonnull transaction) {
+        [self.editingDatabaseConnection readWithBlock:^(YapDatabaseReadTransaction *_Nonnull transaction) {
             messageData = [syncContactsMessage buildPlainTextAttachmentDataWithTransaction:transaction];
             lastMessageData = [transaction objectForKey:kOWSPrimaryStorageOWSContactsSyncingLastMessageKey
                                            inCollection:kOWSPrimaryStorageOWSContactsSyncingCollection];

SignalServiceKit/src/Contacts/TSThread.m

@@ -47,7 +47,14 @@ NS_ASSUME_NONNULL_BEGIN
         _lastMessageDate = nil;
         _creationDate    = [NSDate date];
         _messageDraft    = nil;
-        _conversationColorName = [self.class randomConversationColorName];
+
+        NSString *_Nullable contactId = self.contactIdentifier;
+        if (contactId.length > 0) {
+            // To be consistent with colors synced to desktop
+            _conversationColorName = [self.class stableConversationColorNameForString:contactId];
+        } else {
+            _conversationColorName = [self.class stableConversationColorNameForString:self.uniqueId];
+        }
     }
 
     return self;
@@ -61,8 +68,14 @@ NS_ASSUME_NONNULL_BEGIN
     }
     
     if (!_conversationColorName) {
+        NSString *_Nullable contactId = self.contactIdentifier;
+        if (contactId.length > 0) {
+            // To be consistent with colors synced to desktop
+            _conversationColorName = [self.class stableConversationColorNameForString:contactId];
+        } else {
             _conversationColorName = [self.class stableConversationColorNameForString:self.uniqueId];
         }
+    }
     
     return self;
 }

SignalServiceKit/src/Messages/DeviceSyncing/OWSSyncContactsMessage.h

@@ -21,7 +21,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (nullable instancetype)initWithCoder:(NSCoder *)coder NS_DESIGNATED_INITIALIZER;
 
-- (NSData *)buildPlainTextAttachmentDataWithTransaction:(YapDatabaseReadWriteTransaction *)transaction;
+- (NSData *)buildPlainTextAttachmentDataWithTransaction:(YapDatabaseReadTransaction *)transaction;
 
 @end
 

SignalServiceKit/src/Messages/DeviceSyncing/OWSSyncContactsMessage.m

@@ -71,7 +71,7 @@ NS_ASSUME_NONNULL_BEGIN
     return syncMessageBuilder;
 }
 
-- (NSData *)buildPlainTextAttachmentDataWithTransaction:(YapDatabaseReadWriteTransaction *)transaction
+- (NSData *)buildPlainTextAttachmentDataWithTransaction:(YapDatabaseReadTransaction *)transaction
 {
     id<ContactsManagerProtocol> contactsManager = TextSecureKitEnv.sharedEnv.contactsManager;
 
@@ -87,12 +87,22 @@ NS_ASSUME_NONNULL_BEGIN
             [self.identityManager recipientIdentityForRecipientId:signalAccount.recipientId];
         NSData *_Nullable profileKeyData = [self.profileManager profileKeyDataForRecipientId:signalAccount.recipientId];
 
-        TSContactThread *contactThread = [TSContactThread getOrCreateThreadWithContactId:signalAccount.recipientId transaction:transaction];
+
+        NSString *conversationColorName = (NSString *)^() {
+            TSContactThread *_Nullable contactThread =
+                [TSContactThread fetchObjectWithUniqueID:signalAccount.recipientId transaction:transaction];
+            if (contactThread) {
+                return contactThread.conversationColorName;
+            } else {
+                return [TSThread stableConversationColorNameForString:signalAccount.recipientId];
+            }
+        }();
+
         [contactsOutputStream writeSignalAccount:signalAccount
                                recipientIdentity:recipientIdentity
                                   profileKeyData:profileKeyData
                                  contactsManager:contactsManager
-                           conversationColorName:contactThread.conversationColorName];
+                           conversationColorName:conversationColorName];
     }
 
     [contactsOutputStream flush];