From 5def0429f82c795d820b2307a0301b78dfb1e6b7 Mon Sep 17 00:00:00 2001
From: jhorv <38920027+jhorv@users.noreply.github.com>
Date: Thu, 4 Apr 2024 21:23:03 -0400
Subject: Add support to IVirtualMemoryManager for zero-copy reads (#6251)

* - WritableRegion: enable wrapping IMemoryOwner<byte>
- IVirtualMemoryManager impls of GetWritableRegion() use pooled memory when region is non-contiguous.
- IVirtualMemoryManager: add GetReadOnlySequence() and impls
- ByteMemoryPool: add new method RentCopy()
- ByteMemoryPool: make class static, remove ctor and singleton field from earlier impl

* - BytesReadOnlySequenceSegment: move from Ryujinx.Common.Memory to Ryujinx.Memory
- BytesReadOnlySequenceSegment: add IsContiguousWith() and Replace() methods
- VirtualMemoryManagerBase:
  - remove generic type parameters, instead use ulong for virtual addresses and nuint for host/physical addresses
  - implement IWritableBlock
  - add virtual GetReadOnlySequence() with coalescing of contiguous segments
  - add virtual GetSpan()
  - add virtual GetWritableRegion()
  - add abstract IsMapped()
  - add virtual MapForeign(ulong, nuint, ulong)
  - add virtual Read<T>()
  - add virtual Read(ulong, Span<byte>)
  - add virtual ReadTracked<T>()
  - add virtual SignalMemoryTracking()
  - add virtual Write()
  - add virtual Write<T>()
  - add virtual WriteUntracked()
  - add virtual WriteWithRedundancyCheck()
- VirtualMemoryManagerRefCountedBase: remove generic type parameters
- AddressSpaceManager: remove redundant methods, add required overrides
- HvMemoryManager: remove redundant methods, add required overrides, add overrides for _invalidAccessHandler handling
- MemoryManager: remove redundant methods, add required overrides, add overrides for _invalidAccessHandler handling
- MemoryManagerHostMapped: remove redundant methods, add required overrides, add overrides for _invalidAccessHandler handling
- NativeMemoryManager: add get properties for Pointer and Length
- throughout: removed invalid <inheritdoc/> comments

* make HvMemoryManager class sealed

* remove unused method

* adjust MemoryManagerHostTracked

* let MemoryManagerHostTracked override WriteImpl()
---
 .../Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs  |  2 +-
 src/Ryujinx.Common/Memory/ByteMemoryPool.cs        | 32 ++++++++++------------
 2 files changed, 16 insertions(+), 18 deletions(-)

(limited to 'src/Ryujinx.Common')

diff --git a/src/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs b/src/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs
index df3f8dc9..05fb29ac 100644
--- a/src/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs
+++ b/src/Ryujinx.Common/Memory/ByteMemoryPool.ByteMemoryPoolBuffer.cs
@@ -4,7 +4,7 @@ using System.Threading;
 
 namespace Ryujinx.Common.Memory
 {
-    public sealed partial class ByteMemoryPool
+    public partial class ByteMemoryPool
     {
         /// <summary>
         /// Represents a <see cref="IMemoryOwner{Byte}"/> that wraps an array rented from
diff --git a/src/Ryujinx.Common/Memory/ByteMemoryPool.cs b/src/Ryujinx.Common/Memory/ByteMemoryPool.cs
index 071f56b1..6fd6a98a 100644
--- a/src/Ryujinx.Common/Memory/ByteMemoryPool.cs
+++ b/src/Ryujinx.Common/Memory/ByteMemoryPool.cs
@@ -6,24 +6,8 @@ namespace Ryujinx.Common.Memory
     /// <summary>
     /// Provides a pool of re-usable byte array instances.
     /// </summary>
-    public sealed partial class ByteMemoryPool
+    public static partial class ByteMemoryPool
     {
-        private static readonly ByteMemoryPool _shared = new();
-
-        /// <summary>
-        /// Constructs a <see cref="ByteMemoryPool"/> instance. Private to force access through
-        /// the <see cref="ByteMemoryPool.Shared"/> instance.
-        /// </summary>
-        private ByteMemoryPool()
-        {
-            // No implementation
-        }
-
-        /// <summary>
-        /// Retrieves a shared <see cref="ByteMemoryPool"/> instance.
-        /// </summary>
-        public static ByteMemoryPool Shared => _shared;
-
         /// <summary>
         /// Returns the maximum buffer size supported by this pool.
         /// </summary>
@@ -95,6 +79,20 @@ namespace Ryujinx.Common.Memory
             return buffer;
         }
 
+        /// <summary>
+        /// Copies <paramref name="buffer"/> into a newly rented byte memory buffer.
+        /// </summary>
+        /// <param name="buffer">The byte buffer to copy</param>
+        /// <returns>A <see cref="IMemoryOwner{Byte}"/> wrapping the rented memory with <paramref name="buffer"/> copied to it</returns>
+        public static IMemoryOwner<byte> RentCopy(ReadOnlySpan<byte> buffer)
+        {
+            var copy = RentImpl(buffer.Length);
+
+            buffer.CopyTo(copy.Memory.Span);
+
+            return copy;
+        }
+
         private static ByteMemoryPoolBuffer RentImpl(int length)
         {
             if ((uint)length > Array.MaxLength)
-- 
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