Faster locking on .NET 9.0+ using System.Threading.Lock (#12)

* Faster locking on .NET 9.0+ using System.Threading.Lock

* whitespaces

* proper comment

---------

Co-authored-by: Alex Yumashev <jitbit+github@gmail.com>

Author: MarkCiliaVincenti

FastCache/FastCache.cs

@@ -19,6 +19,7 @@ public class FastCache<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>,
 	{
 		private readonly ConcurrentDictionary<TKey, TtlValue> _dict = new ConcurrentDictionary<TKey, TtlValue>();
 
+		private readonly Lock _lock = new();
 		private readonly Timer _cleanUpTimer;
 		private readonly EvictionCallback _itemEvicted;
 
@@ -65,7 +66,7 @@ await FastCacheStatics.GlobalStaticLock.WaitAsync()
 		public void EvictExpired()
 		{
 			//Eviction already started by another thread? forget it, lets move on
-			if (Monitor.TryEnter(_cleanUpTimer)) //use the timer-object for our lock, it's local, private and instance-type, so its ok
+			if (_lock.TryEnter()) //use the new System.Threading.Lock class for faster locking in .NET9+
 			{
 				List<TKey> evictedKeys = null; // Batch eviction callbacks
 				try
@@ -90,7 +91,7 @@ public void EvictExpired()
 				}
 				finally
 				{
-					Monitor.Exit(_cleanUpTimer);
+                    _lock.Exit();
 				}
 
 				// Trigger batched eviction callbacks outside the loop to prevent flooding the thread pool

FastCache/FastCache.csproj

@@ -1,7 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net6.0;net8.0;net10.0</TargetFrameworks>
+    <TargetFrameworks>net6.0;net8.0;net9.0;net10.0</TargetFrameworks>
+    <LangVersion>latest</LangVersion>
     <PackageId>Jitbit.FastCache</PackageId>
     <Title>FastCache</Title>
     <Authors>Alex from Jitbit</Authors>
@@ -27,4 +28,11 @@
     </None>
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Condition="!$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net9.0'))" Include="Backport.System.Threading.Lock" Version="3.1.5">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>analyzers</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
 </Project>