From 666e05f5cb9aa9dc86874823c108586e7a5b38bd Mon Sep 17 00:00:00 2001
From: jhorv <38920027+jhorv@users.noreply.github.com>
Date: Sun, 23 Apr 2023 22:06:23 -0400
Subject: Reducing Memory Allocations 202303 (#4624)

* use ArrayPool, avoid 6000-7000 allocs/sec of runtime

* use ArrayPool, avoid ~7k allocs/second during game execution

* use ArrayPool, avoid ~3000 allocs/sec during game execution

* use MemoryPool, reduce 0.5 MB/sec of new allocations during game execution

* avoid over-allocation by setting List<> Capacity when known

* remove LINQ in KTimeManager.UnscheduleFutureInvocation

* KTimeManager - avoid spinning one more time when the time has arrived

* KTimeManager - let SpinWait decide when to Thread.Yield(), and don't SpinOnce() immediately after Thread.Yield()

* use MemoryPool, reduce ~175k bytes/sec allocation during game execution

* IpcService - call commands via dynamic methods instead of reflection .Invoke(). Faster to call and with fewer allocations because parameters can be passed directly instead of as an array

* Make ButtonMappingEntry a record struct to avoid allocations. Set the List<ButtonMappingEntry> capacity according to use.

* add MemoryBuffer type for working with MemoryPool<byte>

* update changes to use MemoryBuffer

* make parameter ReadOnlySpan instead of Span

* whitespace fix

* Revert "IpcService - call commands via dynamic methods instead of reflection .Invoke(). Faster to call and with fewer allocations because parameters can be passed directly instead of as an array"

This reverts commit f2c698bdf65f049e8481c9f2ec7138d9b9a8261d.

* tweak KTimeManager spin behavior

* replace MemoryBuffer with ByteMemoryPool modeled after System.Buffers.ArrayMemoryPool<T>

* make ByteMemoryPoolBuffer responsible for renting memory
---
 .../Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs  | 51 ++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs

(limited to 'Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs')

diff --git a/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs b/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs
new file mode 100644
index 00000000..eda350bd
--- /dev/null
+++ b/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs
@@ -0,0 +1,51 @@
+using System;
+using System.Buffers;
+using System.Threading;
+
+namespace Ryujinx.Common.Memory
+{
+    public sealed partial class ByteMemoryPool
+    {
+        /// <summary>
+        /// Represents a <see cref="IMemoryOwner{Byte}"/> that wraps an array rented from
+        /// <see cref="ArrayPool{Byte}.Shared"/> and exposes it as <see cref="Memory{Byte}"/>
+        /// with a length of the requested size.
+        /// </summary>
+        private sealed class ByteMemoryPoolBuffer : IMemoryOwner<byte>
+        {
+            private byte[] _array;
+            private readonly int _length;
+
+            public ByteMemoryPoolBuffer(int length)
+            {
+                _array = ArrayPool<byte>.Shared.Rent(length);
+                _length = length;
+            }
+
+            /// <summary>
+            /// Returns a <see cref="Memory{Byte}"/> belonging to this owner.
+            /// </summary>
+            public Memory<byte> Memory
+            {
+                get
+                {
+                    byte[] array = _array;
+                    
+                    ObjectDisposedException.ThrowIf(array is null, this);
+
+                    return new Memory<byte>(array, 0, _length);
+                }
+            }
+
+            public void Dispose()
+            {
+                var array = Interlocked.Exchange(ref _array, null);
+                
+                if (array != null)
+                {
+                    ArrayPool<byte>.Shared.Return(array);
+                }
+            }
+        }
+    }
+}
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