Switch to using ThreadStatic instead of ArrayPool

Author: arontsang

src/Peachpie.CodeAnalysis/Peachpie.CodeAnalysis.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <TargetFrameworks>net6.0</TargetFrameworks>
     <OutputType>exe</OutputType>
-    <NoWarn>$(NoWarn);1591</NoWarn>
+    <NoWarn>$(NoWarn);1591;RS1009</NoWarn>
     <AssemblyName>Peachpie.CodeAnalysis</AssemblyName>
     <PackageId>Peachpie.CodeAnalysis</PackageId>
     <PackageTags>php;peachpie;dotnet;compiler</PackageTags>

src/Peachpie.Runtime/PhpCallable.ArrayPool.tt

@@ -1,9 +1,23 @@
 <#@ output extension=".tt.cs" #>
 using System;
-using System.Buffers;
-namespace Pchp.Core;
-using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
+namespace Pchp.Core;
+
+file static class PhpCallableArrayCache
+{
+    // Since dotnet 8
+    // ThreadStatic performance is much faster
+    // than ArrayPool
+    // https://devblogs.microsoft.com/dotnet/performance-improvements-in-net-8/#threadstatic
+
+    [ThreadStatic]
+    private static PhpValue[] _cache;
+
+    public static PhpValue[] GetArray()
+    {
+        return _cache ??= new PhpValue[16];
+    }
+}
 
 partial interface IPhpCallable
 {
@@ -33,17 +47,19 @@ partial interface IPhpCallable
 <# } #>
         PhpValue p<#= arity - 1 #>)
     {
-        var phpArgs = ArrayPool<PhpValue>.Shared.Rent(<#= arity #>);
+        var array = PhpCallableArrayCache.GetArray();
+        var memory = new Memory<PhpValue>(array);
+        var phpArgs = memory.Span[..<#= arity #>];
         try
         {
 <# for(int p = 0; p < arity; p++) { #>
             phpArgs[<#= p #>] = p<#= p #>;
 <# } #>
-            return Invoke(ctx, new ReadOnlySpan<PhpValue>(phpArgs, 0, <#= arity #>));
+            return Invoke(ctx, phpArgs);
         }
         finally
         {
-            ArrayPool<PhpValue>.Shared.Return(phpArgs, true);
+            Array.Clear(array, 0, <#= arity #>);
         }
     }