From 4c1235ac974a59f6b719335fb875c30ee7f1aa9e Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 1 May 2022 02:37:33 +0100
Subject: [PATCH] Optimise into_unprepared slightly

Prompted by seeing this optimisation at what ought to be a call site
of this method.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---
 src/updates.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/updates.rs b/src/updates.rs
index 216ca07c..68821f5c 100644
--- a/src/updates.rs
+++ b/src/updates.rs
@@ -1013,10 +1013,14 @@ impl PreparedUpdate {
 impl Vec<(PieceId, PieceUpdateOps)> {
   fn into_unprepared(self, by_client: IsResponseToClientOp)
                      -> UnpreparedUpdates {
-    vec![Box::new(
-      move |buf: &mut PrepareUpdatesBuffer| {
-        buf.piece_updates(self, &by_client)
-      })]
+    if self.len() != 0 {
+      vec![Box::new(
+        move |buf: &mut PrepareUpdatesBuffer| {
+          buf.piece_updates(self, &by_client)
+        })]
+    } else {
+      default()
+    }
   }
 }
 
-- 
2.30.2