perf: Optimize RSE.LateUpdate by patching AudioSource ctor (#42)

Every frame, RocketSoundEnhancement makes a FindObjectsOfType call in
order to discover any new AudioSources that have been created in the
last frame. This is slow.

This commit does away with that by:
- Patching AudioSource::.ctor to add the newly created AudioSource
  object to a list (if there is currently an instance of
  RocketSoundEnhancement active).
- Processing the new items in the list in LateUpdate instead of checking
  all available items.

There might be some further simplifications that can be done here now
that we know that we're only processing new AudioSources. None of them
would have an effect on performance though, so I have left them in just
to be safe.

In my testing this change reduces the time spent in RSE.LateUpdate from
4.4s to 90ms over a 253s launch to orbit.

Author: Phantomical

.github/workflows/build.yml

@@ -14,3 +14,5 @@ on:
 jobs:
   build:
     uses: KSPModdingLibs/KSPBuildTools/.github/workflows/[email protected]
+    with:
+      dependency-identifiers: Harmony2

Source/RocketSoundEnhancement/Patches/AudioSource_Patch.cs

@@ -0,0 +1,17 @@
+using HarmonyLib;
+using UnityEngine;
+using System;
+
+namespace RocketSoundEnhancement.Patches
+{
+    [HarmonyPatch(typeof(AudioSource), MethodType.Constructor, argumentTypes: new Type[0])]
+    internal static class AudioSource_Ctor_Patch
+    {
+        static void Postfix(AudioSource __instance)
+        {
+            RocketSoundEnhancement.Instance?.newAudioSources?.Add(__instance);
+        }
+    }
+}
+
+

Source/RocketSoundEnhancement/RocketSoundEnhancement.cs

@@ -58,13 +58,16 @@ public static AudioMixer Mixer
         private float lastInteriorCutoffFreq;
 
         private HashSet<int> managedSources = new HashSet<int>();
+        internal readonly List<AudioSource> newAudioSources = new List<AudioSource>();
 
         private bool gamePaused;
 
         private void Awake()
         {
             if (instance != null) { Destroy(instance); }
 
+            // Get all the currently existing audio sources.
+            newAudioSources.AddRange((AudioSource[])FindObjectsOfType(typeof(AudioSource)));
             instance = this;
         }
 
@@ -162,27 +165,42 @@ public float WindModulation()
             return Mathf.Lerp(1, windModulation, Mathf.Clamp01((float)FlightGlobals.ActiveVessel.atmDensity));
         }
 
+        bool GetNextAudioSource(out AudioSource source)
+        {
+            if (newAudioSources.Count == 0)
+            {
+                source = null;
+                return false;
+            }
+
+            // This makes sure things still work even if a new audio source ends
+            // up being created while we are running.
+            source = newAudioSources[newAudioSources.Count - 1];
+            newAudioSources.RemoveAt(newAudioSources.Count - 1);
+            return true;
+        }
+
         public void LateUpdate()
         {
             if (gamePaused || !HighLogic.LoadedSceneIsFlight) return;
 
             if (!Settings.EnableAudioEffects || Mixer == null)
             {
-                // TODO: some kind of latch so this only runs once
-                foreach (var sourceObj in FindObjectsOfType(typeof(AudioSource)))
+                while (GetNextAudioSource(out var source))
                 {
-                    AudioSource source = (AudioSource)sourceObj;
-                    if (source != null) source.outputAudioMixerGroup = null;
+                    if (source != null)
+                        source.outputAudioMixerGroup = null;
                 }
+
                 managedSources.Clear();
-                
                 return;
             }
 
             // NOTE: the generic (strongly typed) version of FindObjectsOfType is slower!
-            foreach (var sourceObj in FindObjectsOfType(typeof(AudioSource)))
+            while (GetNextAudioSource(out var source))
             {
-                AudioSource source = (AudioSource)sourceObj;
+                if (source == null)
+                    continue;
 
                 int instanceID = source.GetInstanceID();
 

Source/RocketSoundEnhancement/RocketSoundEnhancement.csproj

@@ -7,26 +7,34 @@
 		<Publicize Include="Assembly-CSharp" IncludeCompilerGeneratedMembers="false" />
 	</ItemGroup>
 
-  <PropertyGroup>
-    <BinariesOutputRelativePath>GameData\RocketSoundEnhancement\Plugins</BinariesOutputRelativePath>
-    <GenerateKSPAssemblyAttribute>true</GenerateKSPAssemblyAttribute>
-    <GenerateKSPAssemblyDependencyAttributes>true</GenerateKSPAssemblyDependencyAttributes>
-  </PropertyGroup>
+	<PropertyGroup>
+		<BinariesOutputRelativePath>GameData\RocketSoundEnhancement\Plugins</BinariesOutputRelativePath>
+		<GenerateKSPAssemblyAttribute>true</GenerateKSPAssemblyAttribute>
+		<GenerateKSPAssemblyDependencyAttributes>true</GenerateKSPAssemblyDependencyAttributes>
+	</PropertyGroup>
 
-  <ItemGroup>
-    <ProjectReference Include="..\RocketSoundEnhancement.Unity\RocketSoundEnhancement.Unity.csproj">
-      <Project>{5dff0176-7ba8-49f4-8155-f5d9b37d7d3d}</Project>
-      <Name>RocketSoundEnhancement.Unity</Name>
-      <Private>False</Private>
-    </ProjectReference>
-  </ItemGroup>
+	<ItemGroup>
+		<ProjectReference
+			Include="..\RocketSoundEnhancement.Unity\RocketSoundEnhancement.Unity.csproj">
+			<Project>{5dff0176-7ba8-49f4-8155-f5d9b37d7d3d}</Project>
+			<Name>RocketSoundEnhancement.Unity</Name>
+			<Private>False</Private>
+		</ProjectReference>
+	</ItemGroup>
 
 	<ItemGroup>
 		<PackageReference Include="Krafs.Publicizer" Version="2.3.0">
-		  <PrivateAssets>all</PrivateAssets>
-		  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+			<PrivateAssets>all</PrivateAssets>
+			<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
 		</PackageReference>
 		<PackageReference Include="KSPBuildTools" Version="0.0.4" />
+
+		<Reference Include="HarmonyKSP">
+			<HintPath>$(KSPRoot)/GameData/000_Harmony/0Harmony.dll</HintPath>
+			<Private>false</Private>
+			<KSPAssembly>HarmonyKSP</KSPAssembly>
+			<KSPAssemblyVersion>2.2.1</KSPAssemblyVersion>
+		</Reference>
 	</ItemGroup>
 
-</Project>
+</Project>

Source/RocketSoundEnhancement/Startup.cs

@@ -1,8 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using HarmonyLib;
 using UnityEngine;
 
 namespace RocketSoundEnhancement
@@ -15,14 +11,17 @@ void Awake()
             AudioConfiguration audioConfig = AudioSettings.GetConfiguration();
             audioConfig.numRealVoices = Settings.VoiceCount;
 
-            if(AudioSettings.Reset(audioConfig)) {
+            if (AudioSettings.Reset(audioConfig)) {
                 Debug.Log("[RSE]: Audio Settings Applied");
                 Debug.Log("[RSE]: DSP Buffer Size : " + AudioSettings.GetConfiguration().dspBufferSize);
                 Debug.Log("[RSE]: Real Voices : " +     AudioSettings.GetConfiguration().numRealVoices);
                 Debug.Log("[RSE]: Virtual Voices : " +  AudioSettings.GetConfiguration().numVirtualVoices);
                 Debug.Log("[RSE]: Samplerate : " +      AudioSettings.GetConfiguration().sampleRate);
                 Debug.Log("[RSE]: Spearker Mode : " +   AudioSettings.GetConfiguration().speakerMode);
             }
+
+            Harmony harmony = new Harmony("RocketSoundEnhancement");
+            harmony.PatchAll(typeof(Startup).Assembly);
         }
     }
 }