Initial support for GPU channels (#2372)

* Ground work for separate GPU channels

* Rename TextureManager to TextureCache

* Decouple texture bindings management from the texture cache

* Rename BufferManager to BufferCache

* Decouple buffer bindings management from the buffer cache

* More comments and proper disposal

* PR feedback

* Force host state update on channel switch

* Typo

* PR feedback

* Missing using

Ryujinx.Graphics.Gpu/GpuChannel.cs

@@ -0,0 +1,78 @@
+using Ryujinx.Graphics.Gpu.Engine.GPFifo;
+using Ryujinx.Graphics.Gpu.Image;
+using Ryujinx.Graphics.Gpu.Memory;
+using System;
+
+namespace Ryujinx.Graphics.Gpu
+{
+    /// <summary>
+    /// Represents a GPU channel.
+    /// </summary>
+    public class GpuChannel : IDisposable
+    {
+        private readonly GpuContext _context;
+        private readonly GPFifoDevice _device;
+        private readonly GPFifoProcessor _processor;
+
+        /// <summary>
+        /// Channel buffer bindings manager.
+        /// </summary>
+        internal BufferManager BufferManager { get; }
+
+        /// <summary>
+        /// Channel texture bindings manager.
+        /// </summary>
+        internal TextureManager TextureManager { get; }
+
+        /// <summary>
+        /// Creates a new instance of a GPU channel.
+        /// </summary>
+        /// <param name="context">GPU context that the channel belongs to</param>
+        internal GpuChannel(GpuContext context)
+        {
+            _context = context;
+            _device = context.GPFifo;
+            _processor = new GPFifoProcessor(context, this);
+            BufferManager = new BufferManager(context);
+            TextureManager = new TextureManager(context, this);
+        }
+
+        /// <summary>
+        /// Push a GPFIFO entry in the form of a prefetched command buffer.
+        /// It is intended to be used by nvservices to handle special cases.
+        /// </summary>
+        /// <param name="commandBuffer">The command buffer containing the prefetched commands</param>
+        public void PushHostCommandBuffer(int[] commandBuffer)
+        {
+            _device.PushHostCommandBuffer(_processor, commandBuffer);
+        }
+
+        /// <summary>
+        /// Pushes GPFIFO entries.
+        /// </summary>
+        /// <param name="entries">GPFIFO entries</param>
+        public void PushEntries(ReadOnlySpan<ulong> entries)
+        {
+            _device.PushEntries(_processor, entries);
+        }
+
+        /// <summary>
+        /// Disposes the GPU channel.
+        /// It's an error to use the GPU channel after disposal.
+        /// </summary>
+        public void Dispose()
+        {
+            _context.DisposedChannels.Enqueue(this);
+        }
+
+        /// <summary>
+        /// Performs disposal of the host GPU resources used by this channel, that are not shared.
+        /// This must only be called from the render thread.
+        /// </summary>
+        internal void Destroy()
+        {
+            BufferManager.Dispose();
+            TextureManager.Dispose();
+        }
+    }
+}