Tighten gameplay hot paths by removing redundant hitobject traversal in note-lock and hitsound selection

osu.Game.Rulesets.Osu/UI/StartTimeOrderedHitPolicy.cs

@@ -30,7 +30,7 @@ public ClickAction CheckHittable(DrawableHitObject hitObject, double time, HitRe
 
             DrawableHitObject? blockingObject = null;
 
-            foreach (var obj in enumerateHitObjectsUpTo(hitObject.HitObject.StartTime))
+            foreach (var obj in enumerateTopLevelAliveObjectsUpTo(hitObject.HitObject.StartTime))
             {
                 if (hitObjectCanBlockFutureHits(obj))
                     blockingObject = obj;
@@ -60,7 +60,7 @@ public void HandleHit(DrawableHitObject hitObject)
                 throw new InvalidOperationException($"A {hitObject} was hit before it became hittable!");
 
             // Miss all hitobjects prior to the hit one.
-            foreach (var obj in enumerateHitObjectsUpTo(hitObject.HitObject.StartTime))
+            foreach (var obj in enumerateTopLevelAliveObjectsUpTo(hitObject.HitObject.StartTime))
             {
                 if (obj.Judged)
                     continue;
@@ -77,22 +77,14 @@ public void HandleHit(DrawableHitObject hitObject)
         private static bool hitObjectCanBlockFutureHits(DrawableHitObject hitObject)
             => hitObject is DrawableHitCircle;
 
-        private IEnumerable<DrawableHitObject> enumerateHitObjectsUpTo(double targetTime)
+        private IEnumerable<DrawableHitObject> enumerateTopLevelAliveObjectsUpTo(double targetTime)
         {
             foreach (var obj in HitObjectContainer!.AliveObjects)
             {
                 if (obj.HitObject.StartTime >= targetTime)
                     yield break;
 
                 yield return obj;
-
-                foreach (var nestedObj in obj.NestedHitObjects)
-                {
-                    if (nestedObj.HitObject.StartTime >= targetTime)
-                        break;
-
-                    yield return nestedObj;
-                }
             }
         }
     }

osu.Game/Rulesets/UI/GameplaySampleTriggerSource.cs

@@ -126,7 +126,8 @@ protected override void Update()
                 // In the case there are no non-judged objects, the last hit object should be used instead.
                 if (candidate == null)
                 {
-                    mostValidObject = hitObjectContainer.Entries.LastOrDefault();
+                    var (_, lastEntry) = getEntryBounds();
+                    mostValidObject = lastEntry;
                 }
                 else
                 {
@@ -136,7 +137,8 @@ protected override void Update()
                     }
                     else
                     {
-                        mostValidObject ??= hitObjectContainer.Entries.FirstOrDefault();
+                        var (firstEntry, _) = getEntryBounds();
+                        mostValidObject ??= firstEntry;
                     }
                 }
             }
@@ -177,6 +179,23 @@ protected override void Update()
             return best ?? mostValidObject.HitObject;
         }
 
+        private (HitObjectLifetimeEntry? first, HitObjectLifetimeEntry? last) getEntryBounds()
+        {
+            HitObjectLifetimeEntry? first = null;
+            HitObjectLifetimeEntry? last = null;
+
+            foreach (var entry in hitObjectContainer.Entries)
+            {
+                if (first == null || entry.HitObject.StartTime < first.HitObject.StartTime)
+                    first = entry;
+
+                if (last == null || entry.HitObject.StartTime > last.HitObject.StartTime)
+                    last = entry;
+            }
+
+            return (first, last);
+        }
+
         private bool isAlreadyHit(HitObjectLifetimeEntry h) => h.AllJudged;
         private bool isCloseEnoughToCurrentTime(HitObject h) => getReferenceTime() >= h.StartTime - h.HitWindows.WindowFor(HitResult.Miss) * 2;