benchmark migration

SignalMessaging/environment/migrations/OWS110SortIdMigration.swift

@@ -13,7 +13,15 @@ class OWS110SortIdMigration: OWSDatabaseMigration {
 
     override public func runUp(completion: @escaping OWSDatabaseMigrationCompletion) {
         Logger.debug("")
+        BenchAsync(title: "Sort Migration") { completeBenchmark in
+            self.doMigration {
+                completeBenchmark()
+                completion()
+            }
+        }
+    }
 
+    private func doMigration(completion: @escaping OWSDatabaseMigrationCompletion) {
         // TODO batch this?
         self.dbReadWriteConnection().readWrite { transaction in
 

SignalMessaging/utils/Bench.swift

@@ -4,7 +4,16 @@
 
 import Foundation
 
-public func BenchAsync(title: String, block: (() -> Void) -> Void) {
+/// Benchmark async code by calling the passed in block parameter when the work
+/// is done.
+///
+///     BenchAsync(title: "my benchmark") { completeBenchmark in
+///         foo {
+///             completeBenchmark()
+///             fooCompletion()
+///         }
+///     }
+public func BenchAsync(title: String, block: (@escaping () -> Void) -> Void) {
     let startTime = CFAbsoluteTimeGetCurrent()
 
     block {