Fix 'mutation during enumeration' and 'bad ordering' crashes.

SignalMessaging/environment/migrations/OWS110SortIdMigration.swift

@@ -49,8 +49,13 @@ public class OWS110SortIdMigration: OWSDatabaseMigration {
             let totalCount: UInt = legacySorting.numberOfItemsInAllGroups()
             var completedCount: UInt = 0
 
-            var seenGroups: Set<String> = Set()
+            var allGroups = [String]()
             legacySorting.enumerateGroups { group, _ in
+                allGroups.append(group)
+            }
+
+            var seenGroups: Set<String> = Set()
+            for group in allGroups {
                 autoreleasepool {
                     // Sanity Check #1
                     // Make sure our enumeration is monotonically increasing.
@@ -69,15 +74,20 @@ public class OWS110SortIdMigration: OWSDatabaseMigration {
                     }
                     seenGroups.insert(group)
 
-                    legacySorting.enumerateKeysAndObjects(inGroup: group) { (_, _, object, _, _) in
+                    var groupKeys = [String]()
+                    legacySorting.enumerateKeys(inGroup: group, using: { (_, key, _, _) in
+                        groupKeys.append(key)
+                    })
+                    let groupKeyBatchSize: Int = 1024
+                    for batch in groupKeys.chunked(by: groupKeyBatchSize) {
                         autoreleasepool {
-                            guard let interaction = object as? TSInteraction else {
+                            for uniqueId in batch {
-                                owsFailDebug("unexpected object: \(type(of: object))")
+                                guard let interaction = TSInteraction.fetch(uniqueId: uniqueId, transaction: transaction) else {
+                                    owsFailDebug("Could not load interaction: \(uniqueId)")
                                     return
                                 }
-
+                                if interaction.timestampForLegacySorting() < previousTimestampForLegacySorting {
-                            guard interaction.timestampForLegacySorting() >= previousTimestampForLegacySorting else {
+                                    owsFailDebug("unexpected object ordering previousTimestampForLegacySorting: \(previousTimestampForLegacySorting) interaction.timestampForLegacySorting: \(interaction.timestampForLegacySorting())")
-                                owsFail("unexpected object ordering previousTimestampForLegacySorting: \(previousTimestampForLegacySorting) interaction.timestampForLegacySorting: \(interaction.timestampForLegacySorting)")
                                 }
                                 previousTimestampForLegacySorting = interaction.timestampForLegacySorting()
 
@@ -92,6 +102,7 @@ public class OWS110SortIdMigration: OWSDatabaseMigration {
                         }
                     }
                 }
+            }
 
             Logger.info("re-archiving \(archivedThreads.count) threads which were previously archived")
             for archivedThread in archivedThreads {