From 3dd36f5f074c4613318ab2ac3b3ed10d4a2fb615 Mon Sep 17 00:00:00 2001
From: CasualPokePlayer <50538166+CasualPokePlayer@users.noreply.github.com>
Date: Sat, 3 Dec 2022 18:30:09 -0800
Subject: [PATCH] revert the explicit try/finally use for PeekByte/PokeByte
 monitor domain methods, testing seems to show the ref struct use makes
 EnterExit allocation (now forced to the stack) a non-issue performance wise

---
 src/BizHawk.Common/IMonitor.cs                | 11 ++++----
 .../Base Implementations/MemoryDomainImpls.cs | 28 +++----------------
 .../Arcades/MAME/MAME.MemoryDomains.cs        | 28 +++----------------
 .../Waterbox/WaterboxMemoryDomain.cs          | 23 +++------------
 4 files changed, 18 insertions(+), 72 deletions(-)

diff --git a/src/BizHawk.Common/IMonitor.cs b/src/BizHawk.Common/IMonitor.cs
index 76301ec555..172f6ba50c 100644
--- a/src/BizHawk.Common/IMonitor.cs
+++ b/src/BizHawk.Common/IMonitor.cs
@@ -15,11 +15,12 @@ namespace BizHawk.Common
 			=> new(m);
 
 		public readonly ref struct EnterExitWrapper
-		{
-			// yes, this can be null
-			private readonly IMonitor? _m;
-
-			public EnterExitWrapper(IMonitor? m)
+		{
+			// yes, this can be null
+			private readonly IMonitor? _m;
+
+			// disallow public construction outside of EnterExit extension
+			internal EnterExitWrapper(IMonitor? m)
 			{
 				_m = m;
 				_m?.Enter();
diff --git a/src/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs b/src/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs
index b484206604..060a3fa506 100644
--- a/src/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs	
+++ b/src/BizHawk.Emulation.Common/Base Implementations/MemoryDomainImpls.cs	
@@ -251,15 +251,10 @@ namespace BizHawk.Emulation.Common
 		{
 			if ((ulong)addr < (ulong)Size)
 			{
-				try
+				using (_monitor.EnterExit())
 				{
-					_monitor.Enter();
 					return ((byte*)Data)[addr];
 				}
-				finally
-				{
-					_monitor.Exit();
-				}
 			}
 
 			throw new ArgumentOutOfRangeException(nameof(addr));
@@ -271,15 +266,10 @@ namespace BizHawk.Emulation.Common
 			{
 				if ((ulong)addr < (ulong)Size)
 				{
-					try
+					using (_monitor.EnterExit())
 					{
-						_monitor.Enter();
 						((byte*)Data)[addr] = val;
 					}
-					finally
-					{
-						_monitor.Exit();
-					}
 				}
 				else
 				{
@@ -361,15 +351,10 @@ namespace BizHawk.Emulation.Common
 		{
 			if ((ulong)addr < (ulong)Size)
 			{
-				try
+				using (_monitor.EnterExit())
 				{
-					_monitor.Enter();
 					return ((byte*)Data)[addr ^ 1];
 				}
-				finally
-				{
-					_monitor.Exit();
-				}
 			}
 
 			throw new ArgumentOutOfRangeException(nameof(addr));
@@ -381,15 +366,10 @@ namespace BizHawk.Emulation.Common
 			{
 				if ((ulong)addr < (ulong)Size)
 				{
-					try
+					using (_monitor.EnterExit())
 					{
-						_monitor.Enter();
 						((byte*)Data)[addr ^ 1] = val;
 					}
-					finally
-					{
-						_monitor.Exit();
-					}
 				}
 				else
 				{
diff --git a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.MemoryDomains.cs b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.MemoryDomains.cs
index 71ecc2da3e..2e91f881b8 100644
--- a/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.MemoryDomains.cs
+++ b/src/BizHawk.Emulation.Cores/Arcades/MAME/MAME.MemoryDomains.cs
@@ -35,38 +35,18 @@ namespace BizHawk.Emulation.Cores.Arcades.MAME
 
 			public override byte PeekByte(long addr)
 			{
-				if (addr < 0 || addr >= _systemBusSize) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
-
+				if ((ulong)addr < (ulong)_systemBusSize) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
 				addr += _firstOffset;
-
-				try
-				{
-					_monitor.Enter();
-					return _core.mame_read_byte((uint)addr << _systemBusAddressShift);
-				}
-				finally
-				{
-					_monitor.Exit();	
-				}
+				return _core.mame_read_byte((uint)addr << _systemBusAddressShift);
 			}
 
 			public override void PokeByte(long addr, byte val)
 			{
 				if (Writable)
 				{
-					if (addr < 0 || addr >= _systemBusSize) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
-
+					if ((ulong)addr < (ulong)_systemBusSize) throw new ArgumentOutOfRangeException(paramName: nameof(addr), addr, message: "address out of range");
 					addr += _firstOffset;
-
-					try
-					{
-						_monitor.Enter();
-						_core.mame_lua_execute($"{MAMELuaCommand.GetSpace}:write_u8({addr << _systemBusAddressShift}, {val})");
-					}
-					finally
-					{
-						_monitor.Exit();
-					}
+					_core.mame_lua_execute($"{MAMELuaCommand.GetSpace}:write_u8({addr << _systemBusAddressShift}, {val})");
 				}
 			}
 
diff --git a/src/BizHawk.Emulation.Cores/Waterbox/WaterboxMemoryDomain.cs b/src/BizHawk.Emulation.Cores/Waterbox/WaterboxMemoryDomain.cs
index d1f501e51e..7d0dcb1848 100644
--- a/src/BizHawk.Emulation.Cores/Waterbox/WaterboxMemoryDomain.cs
+++ b/src/BizHawk.Emulation.Cores/Waterbox/WaterboxMemoryDomain.cs
@@ -20,7 +20,7 @@ namespace BizHawk.Emulation.Cores.Waterbox
 		public static WaterboxMemoryDomain Create(MemoryArea m, WaterboxHost monitor)
 		{
 			return m.Flags.HasFlag(MemoryDomainFlags.FunctionHook)
-				? (WaterboxMemoryDomain)new WaterboxMemoryDomainFunc(m, monitor)
+				? new WaterboxMemoryDomainFunc(m, monitor)
 				: new WaterboxMemoryDomainPointer(m, monitor);
 		}
 
@@ -73,15 +73,10 @@ namespace BizHawk.Emulation.Cores.Waterbox
 		{
 			if ((ulong)addr < (ulong)Size)
 			{
-				try
+				using (_monitor.EnterExit())
 				{
-					_monitor.Enter();
 					return ((byte*)_data)[addr ^ _addressMangler];
 				}
-				finally
-				{
-					_monitor.Exit();
-				}
 			}
 
 			throw new ArgumentOutOfRangeException(nameof(addr));
@@ -93,15 +88,10 @@ namespace BizHawk.Emulation.Cores.Waterbox
 			{
 				if ((ulong)addr < (ulong)Size)
 				{
-					try
+					using (_monitor.EnterExit())
 					{
-						_monitor.Enter();
 						((byte*)_data)[addr ^ _addressMangler] = val;
 					}
-					finally
-					{
-						_monitor.Exit();
-					}
 				}
 				else
 				{
@@ -123,15 +113,10 @@ namespace BizHawk.Emulation.Cores.Waterbox
 
 			if (start < (ulong)Size && (start + count) <= (ulong)Size)
 			{
-				try
+				using (_monitor.EnterExit())
 				{
-					_monitor.Enter();
 					Marshal.Copy(Z.US((ulong)_data + start), values, 0, (int)count);
 				}
-				finally
-				{
-					_monitor.Exit();
-				}
 			}
 			else
 			{