From f13ca28d5eae95792bb6cdac1e75f05f56d26c2a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bart=C5=82omiej=20Dach?= <dach.bartlomiej@gmail.com>
Date: Tue, 4 Jun 2024 10:25:08 +0200
Subject: [PATCH] Fix performance overhead from ternary state bindable
 callbacks when selection is changing

Closes https://github.com/ppy/osu/issues/28369.

The reporter of the issue was incorrect; it's not the beat snap grid
that is causing the problem, it's something far stupider than that.

When the current selection changes,
`EditorSelectionHandler.UpdateTernaryStates()` is supposed to update the
state of ternary bindables to reflect the reality of the current
selection. This in turn will fire bindable change callbacks for said
ternary toggles, which heavily use `EditorBeatmap.PerformOnSelection()`.

The thing about that method is that it will attempt to check whether any
changes were actually made to avoid producing empty undo states, *but*
to do this, it must *serialise out the entire beatmap to a stream* and
then *binary equality check that* to determine whether any changes were
actually made:

	https://github.com/ppy/osu/blob/7b14c77e43e4ee96775a9fcb6843324170fa70bb/osu.Game/Screens/Edit/EditorChangeHandler.cs#L65-L69

As goes without saying, this is very expensive and unnecessary, which
leads to stuff like keeping a selection box active while a taiko beatmap
is playing under it dog slow. So to attempt to mitigate that, add
precondition checks to every single ternary callback of this sort to
avoid this serialisation overhead.

And yes, those precondition checks use linq, and that is *still* faster
than not having them.
---
 .../Edit/TaikoSelectionHandler.cs                    |  6 ++++++
 .../Compose/Components/EditorSelectionHandler.cs     | 12 ++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/osu.Game.Rulesets.Taiko/Edit/TaikoSelectionHandler.cs b/osu.Game.Rulesets.Taiko/Edit/TaikoSelectionHandler.cs
index 7ab8a54b02..ae6dced9aa 100644
--- a/osu.Game.Rulesets.Taiko/Edit/TaikoSelectionHandler.cs
+++ b/osu.Game.Rulesets.Taiko/Edit/TaikoSelectionHandler.cs
@@ -53,6 +53,9 @@ namespace osu.Game.Rulesets.Taiko.Edit
 
         public void SetStrongState(bool state)
         {
+            if (SelectedItems.OfType<Hit>().All(h => h.IsStrong == state))
+                return;
+
             EditorBeatmap.PerformOnSelection(h =>
             {
                 if (!(h is Hit taikoHit)) return;
@@ -67,6 +70,9 @@ namespace osu.Game.Rulesets.Taiko.Edit
 
         public void SetRimState(bool state)
         {
+            if (SelectedItems.OfType<Hit>().All(h => h.Type == (state ? HitType.Rim : HitType.Centre)))
+                return;
+
             EditorBeatmap.PerformOnSelection(h =>
             {
                 if (h is Hit taikoHit)
diff --git a/osu.Game/Screens/Edit/Compose/Components/EditorSelectionHandler.cs b/osu.Game/Screens/Edit/Compose/Components/EditorSelectionHandler.cs
index a73278a61e..7420362e19 100644
--- a/osu.Game/Screens/Edit/Compose/Components/EditorSelectionHandler.cs
+++ b/osu.Game/Screens/Edit/Compose/Components/EditorSelectionHandler.cs
@@ -198,6 +198,9 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <param name="bankName">The name of the sample bank.</param>
         public void AddSampleBank(string bankName)
         {
+            if (SelectedItems.All(h => h.Samples.All(s => s.Bank == bankName)))
+                return;
+
             EditorBeatmap.PerformOnSelection(h =>
             {
                 if (h.Samples.All(s => s.Bank == bankName))
@@ -214,6 +217,9 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <param name="sampleName">The name of the hit sample.</param>
         public void AddHitSample(string sampleName)
         {
+            if (SelectedItems.All(h => h.Samples.Any(s => s.Name == sampleName)))
+                return;
+
             EditorBeatmap.PerformOnSelection(h =>
             {
                 // Make sure there isn't already an existing sample
@@ -231,6 +237,9 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <param name="sampleName">The name of the hit sample.</param>
         public void RemoveHitSample(string sampleName)
         {
+            if (SelectedItems.All(h => h.Samples.All(s => s.Name != sampleName)))
+                return;
+
             EditorBeatmap.PerformOnSelection(h =>
             {
                 h.SamplesBindable.RemoveAll(s => s.Name == sampleName);
@@ -245,6 +254,9 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <exception cref="InvalidOperationException">Throws if any selected object doesn't implement <see cref="IHasComboInformation"/></exception>
         public void SetNewCombo(bool state)
         {
+            if (SelectedItems.OfType<IHasComboInformation>().All(h => h.NewCombo == state))
+                return;
+
             EditorBeatmap.PerformOnSelection(h =>
             {
                 var comboInfo = h as IHasComboInformation;