optimize SvtBroadcaster::Normalize() a bit more (tdf#132454)

A common case is just one unsorted item at the end, in that case
it's even more efficient to simply insert it in the right place.
This further improves the tdf#132454 undo operation 36s->27s.

Change-Id: I29db80fb8292e827b655000cddc462cf87cb485d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/97088
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>
Tested-by: Jenkins

1 files changed, 11 insertions, 4 deletions

diff --git a/svl/source/notify/broadcast.cxx b/svl/source/notify/broadcast.cxx
index cc1ffcb10917..de7ec6b4374e 100644
--- a/svl/source/notify/broadcast.cxx
+++ b/svl/source/notify/broadcast.cxx
@@ -29,13 +29,20 @@ void SvtBroadcaster::Normalize() const
     if (!mbNormalized)
     {
         // Add() only appends new values, so often the container will be sorted expect for one
-        // or few last items. For larger containers it is much more efficient to just sort
-        // the unsorted part and then merge.
+        // or few last items. For larger containers it is much more efficient to just handle
+        // the unsorted part.
         if(maListeners.size() > 100)
         {
             auto sortedEnd = std::is_sorted_until(maListeners.begin(),maListeners.end());
-            if( o3tl::make_unsigned( sortedEnd - maListeners.begin()) > maListeners.size() * 3 / 4 )
-            {
+            if( maListeners.end() - sortedEnd == 1 )
+            {   // Just one item, insert it in the right place.
+                SvtListener* item = maListeners.back();
+                maListeners.pop_back();
+                maListeners.insert( std::upper_bound( maListeners.begin(), maListeners.end(), item ), item );
+                mbNormalized = true;
+            }
+            else if( o3tl::make_unsigned( sortedEnd - maListeners.begin()) > maListeners.size() * 3 / 4 )
+            {   // Sort the unsorted part and then merge.
                 std::sort( sortedEnd, maListeners.end());
                 std::inplace_merge( maListeners.begin(), sortedEnd, maListeners.end());
                 mbNormalized = true;