Use pooled memory and avoid memory copies (#6691)

* perf: use ByteMemoryPool

* feat: KPageTableBase/KPageTable new methods to read and write `ReadOnlySequence<byte>`

* new: add IWritableBlock.Write(ulong, ReadOnlySequence<byte>) with default impl

* perf: use GetReadOnlySequence() instead of GetSpan()

* perf: make `Parcel` IDisposable, use `ByteMemoryPool` for internal allocation, and make Parcel consumers dispose of it

* remove comment about copySize

* remove unnecessary Clear()

2 files changed, 26 insertions, 10 deletions

diff --git a/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/IBinder.cs b/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/IBinder.cs
index 0fb2dfd2..54aac48a 100644
--- a/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/IBinder.cs
+++ b/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/IBinder.cs
@@ -13,10 +13,10 @@ namespace Ryujinx.HLE.HOS.Services.SurfaceFlinger
 
         ResultCode OnTransact(uint code, uint flags, ReadOnlySpan<byte> inputParcel, Span<byte> outputParcel)
         {
-            Parcel inputParcelReader = new(inputParcel.ToArray());
+            using Parcel inputParcelReader = new(inputParcel);
 
             // TODO: support objects?
-            Parcel outputParcelWriter = new((uint)(outputParcel.Length - Unsafe.SizeOf<ParcelHeader>()), 0);
+            using Parcel outputParcelWriter = new((uint)(outputParcel.Length - Unsafe.SizeOf<ParcelHeader>()), 0);
 
             string inputInterfaceToken = inputParcelReader.ReadInterfaceToken();
 
diff --git a/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/Parcel.cs b/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/Parcel.cs
index 4ac0525b..c6cd60d0 100644
--- a/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/Parcel.cs
+++ b/src/Ryujinx.HLE/HOS/Services/SurfaceFlinger/Parcel.cs
@@ -1,7 +1,9 @@
 using Ryujinx.Common;
+using Ryujinx.Common.Memory;
 using Ryujinx.Common.Utilities;
 using Ryujinx.HLE.HOS.Services.SurfaceFlinger.Types;
 using System;
+using System.Buffers;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
@@ -9,13 +11,13 @@ using System.Text;
 
 namespace Ryujinx.HLE.HOS.Services.SurfaceFlinger
 {
-    class Parcel
+    sealed class Parcel : IDisposable
     {
-        private readonly byte[] _rawData;
+        private readonly IMemoryOwner<byte> _rawDataOwner;
 
-        private Span<byte> Raw => new(_rawData);
+        private Span<byte> Raw => _rawDataOwner.Memory.Span;
 
-        private ref ParcelHeader Header => ref MemoryMarshal.Cast<byte, ParcelHeader>(_rawData)[0];
+        private ref ParcelHeader Header => ref MemoryMarshal.Cast<byte, ParcelHeader>(Raw)[0];
 
         private Span<byte> Payload => Raw.Slice((int)Header.PayloadOffset, (int)Header.PayloadSize);
 
@@ -24,9 +26,11 @@ namespace Ryujinx.HLE.HOS.Services.SurfaceFlinger
         private int _payloadPosition;
         private int _objectPosition;
 
-        public Parcel(byte[] rawData)
+        private bool _isDisposed;
+
+        public Parcel(ReadOnlySpan<byte> data)
         {
-            _rawData = rawData;
+            _rawDataOwner = ByteMemoryPool.RentCopy(data);
 
             _payloadPosition = 0;
             _objectPosition = 0;
@@ -36,7 +40,7 @@ namespace Ryujinx.HLE.HOS.Services.SurfaceFlinger
         {
             uint headerSize = (uint)Unsafe.SizeOf<ParcelHeader>();
 
-            _rawData = new byte[BitUtils.AlignUp<uint>(headerSize + payloadSize + objectsSize, 4)];
+            _rawDataOwner = ByteMemoryPool.RentCleared(BitUtils.AlignUp<uint>(headerSize + payloadSize + objectsSize, 4));
 
             Header.PayloadSize = payloadSize;
             Header.ObjectsSize = objectsSize;
@@ -132,7 +136,9 @@ namespace Ryujinx.HLE.HOS.Services.SurfaceFlinger
 
             // TODO: figure out what this value is
 
-            WriteInplaceObject(new byte[4] { 0, 0, 0, 0 });
+            Span<byte> fourBytes = stackalloc byte[4];
+
+            WriteInplaceObject(fourBytes);
         }
 
         public AndroidStrongPointer<T> ReadStrongPointer<T>() where T : unmanaged, IFlattenable
@@ -219,5 +225,15 @@ namespace Ryujinx.HLE.HOS.Services.SurfaceFlinger
 
             return Raw[..(int)(Header.PayloadSize + Header.ObjectsSize + Unsafe.SizeOf<ParcelHeader>())];
         }
+
+        public void Dispose()
+        {
+            if (!_isDisposed)
+            {
+                _isDisposed = true;
+
+                _rawDataOwner.Dispose();
+            }
+        }
     }
 }