From 5cd43b3a7fc2f267628e5b1b979affa52d4f9e2d Mon Sep 17 00:00:00 2001
From: Samuel Cattini-Schultz <syriiins@gmail.com>
Date: Tue, 6 Apr 2021 11:53:31 +1000
Subject: [PATCH] Set default history retention to 0 for Skill and override in
 StrainSkill

Some skills might not even require history retention, so why waste the allocations?
---
 osu.Game/Rulesets/Difficulty/Skills/Skill.cs       | 10 +++++-----
 osu.Game/Rulesets/Difficulty/Skills/StrainSkill.cs | 13 +++++++++++++
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/osu.Game/Rulesets/Difficulty/Skills/Skill.cs b/osu.Game/Rulesets/Difficulty/Skills/Skill.cs
index 94d823f2ad..ebd389d823 100644
--- a/osu.Game/Rulesets/Difficulty/Skills/Skill.cs
+++ b/osu.Game/Rulesets/Difficulty/Skills/Skill.cs
@@ -22,8 +22,9 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// Soft capacity of the <see cref="Previous"/> queue.
         /// <see cref="Previous"/> will automatically resize if it exceeds capacity, but will do so at a very slight performance impact.
         /// The actual capacity will be set to this value + 1 to allow for storage of the current object before the next can be processed.
+        /// Setting to zero (default) will cause <see cref="Previous"/> to be uninstanciated.
         /// </summary>
-        protected virtual int PreviousCollectionSoftCapacity => 1;
+        protected virtual int PreviousCollectionSoftCapacity => 0;
 
         /// <summary>
         /// Mods for use in skill calculations.
@@ -35,7 +36,9 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         protected Skill(Mod[] mods)
         {
             this.mods = mods;
-            Previous = new ReverseQueue<DifficultyHitObject>(PreviousCollectionSoftCapacity + 1);
+
+            if (PreviousCollectionSoftCapacity > 0)
+                Previous = new ReverseQueue<DifficultyHitObject>(PreviousCollectionSoftCapacity + 1);
         }
 
         internal void ProcessInternal(DifficultyHitObject current)
@@ -51,8 +54,6 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// <param name="current">The <see cref="DifficultyHitObject"/> to be processed.</param>
         protected virtual void RemoveExtraneousHistory(DifficultyHitObject current)
         {
-            while (Previous.Count > 1)
-                Previous.Dequeue();
         }
 
         /// <summary>
@@ -61,7 +62,6 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// <param name="current">The <see cref="DifficultyHitObject"/> that was just processed.</param>
         protected virtual void AddToHistory(DifficultyHitObject current)
         {
-            Previous.Enqueue(current);
         }
 
         /// <summary>
diff --git a/osu.Game/Rulesets/Difficulty/Skills/StrainSkill.cs b/osu.Game/Rulesets/Difficulty/Skills/StrainSkill.cs
index 71cee36812..16816be35c 100644
--- a/osu.Game/Rulesets/Difficulty/Skills/StrainSkill.cs
+++ b/osu.Game/Rulesets/Difficulty/Skills/StrainSkill.cs
@@ -20,6 +20,8 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         /// </summary>
         protected abstract double SkillMultiplier { get; }
 
+        protected override int PreviousCollectionSoftCapacity => 1;
+
         /// <summary>
         /// Determines how quickly strain decays for the given skill.
         /// For example a value of 0.15 indicates that strain decays to 15% of its original value in one second.
@@ -52,6 +54,17 @@ namespace osu.Game.Rulesets.Difficulty.Skills
         {
         }
 
+        protected override void RemoveExtraneousHistory(DifficultyHitObject current)
+        {
+            while (Previous.Count > 1)
+                Previous.Dequeue();
+        }
+
+        protected override void AddToHistory(DifficultyHitObject current)
+        {
+            Previous.Enqueue(current);
+        }
+
         /// <summary>
         /// Process a <see cref="DifficultyHitObject"/> and update current strain values accordingly.
         /// </summary>