1 files changed, 120 insertions, 0 deletions
diff --git a/src/Ryujinx.Graphics.OpenGL/Queries/BufferedQuery.cs b/src/Ryujinx.Graphics.OpenGL/Queries/BufferedQuery.cs
new file mode 100644
index 00000000..9d43f6c3
--- /dev/null
+++ b/src/Ryujinx.Graphics.OpenGL/Queries/BufferedQuery.cs
@@ -0,0 +1,120 @@
+using OpenTK.Graphics.OpenGL;
+using Ryujinx.Common.Logging;
+using System;
+using System.Runtime.InteropServices;
+using System.Threading;
+
+namespace Ryujinx.Graphics.OpenGL.Queries
+{
+    class BufferedQuery : IDisposable
+    {
+        private const int MaxQueryRetries = 5000;
+        private const long DefaultValue = -1;
+        private const ulong HighMask = 0xFFFFFFFF00000000;
+
+        public int Query { get; }
+
+        private int _buffer;
+        private IntPtr _bufferMap;
+        private QueryTarget _type;
+
+        public BufferedQuery(QueryTarget type)
+        {
+            _buffer = GL.GenBuffer();
+            Query = GL.GenQuery();
+            _type = type;
+
+            GL.BindBuffer(BufferTarget.QueryBuffer, _buffer);
+
+            unsafe
+            {
+                long defaultValue = DefaultValue;
+                GL.BufferStorage(BufferTarget.QueryBuffer, sizeof(long), (IntPtr)(&defaultValue), BufferStorageFlags.MapReadBit | BufferStorageFlags.MapWriteBit | BufferStorageFlags.MapPersistentBit);
+            }
+            _bufferMap = GL.MapBufferRange(BufferTarget.QueryBuffer, IntPtr.Zero, sizeof(long), BufferAccessMask.MapReadBit | BufferAccessMask.MapWriteBit | BufferAccessMask.MapPersistentBit);
+        }
+
+        public void Reset()
+        {
+            GL.EndQuery(_type);
+            GL.BeginQuery(_type, Query);
+        }
+
+        public void Begin()
+        {
+            GL.BeginQuery(_type, Query);
+        }
+
+        public unsafe void End(bool withResult)
+        {
+            GL.EndQuery(_type);
+
+            if (withResult)
+            {
+                GL.BindBuffer(BufferTarget.QueryBuffer, _buffer);
+
+                Marshal.WriteInt64(_bufferMap, -1L);
+                GL.GetQueryObject(Query, GetQueryObjectParam.QueryResult, (long*)0);
+                GL.MemoryBarrier(MemoryBarrierFlags.QueryBufferBarrierBit | MemoryBarrierFlags.ClientMappedBufferBarrierBit);
+            }
+            else
+            {
+                // Dummy result, just return 0.
+                Marshal.WriteInt64(_bufferMap, 0L);
+            }
+        }
+
+        private bool WaitingForValue(long data)
+        {
+            return data == DefaultValue ||
+                ((ulong)data & HighMask) == (unchecked((ulong)DefaultValue) & HighMask);
+        }
+
+        public bool TryGetResult(out long result)
+        {
+            result = Marshal.ReadInt64(_bufferMap);
+
+            return !WaitingForValue(result);
+        }
+
+        public long AwaitResult(AutoResetEvent wakeSignal = null)
+        {
+            long data = DefaultValue;
+
+            if (wakeSignal == null)
+            {
+                while (WaitingForValue(data))
+                {
+                    data = Marshal.ReadInt64(_bufferMap);
+                }
+            }
+            else
+            {
+                int iterations = 0;
+                while (WaitingForValue(data) && iterations++ < MaxQueryRetries)
+                {
+                    data = Marshal.ReadInt64(_bufferMap);
+                    if (WaitingForValue(data))
+                    {
+                        wakeSignal.WaitOne(1);
+                    }
+                }
+
+                if (iterations >= MaxQueryRetries)
+                {
+                    Logger.Error?.Print(LogClass.Gpu, $"Error: Query result timed out. Took more than {MaxQueryRetries} tries.");
+                }
+            }
+
+            return data;
+        }
+
+        public void Dispose()
+        {
+            GL.BindBuffer(BufferTarget.QueryBuffer, _buffer);
+            GL.UnmapBuffer(BufferTarget.QueryBuffer);
+            GL.DeleteBuffer(_buffer);
+            GL.DeleteQuery(Query);
+        }
+    }
+}