HTTP2: Fix HttpRequestHeaders no longer being pooled (#19329)

src/Servers/Kestrel/Core/src/Internal/Http/HttpHeaders.Generated.cs

@@ -6105,7 +6105,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 }
 
                 // We didn't have a previous matching header value, or have already added a header, so get the string for this value.
-                var valueStr = value.GetRequestHeaderStringNonNullCharacters(_useLatin1);
+                var valueStr = value.GetRequestHeaderStringNonNullCharacters(UseLatin1);
                 if ((_bits & flag) == 0)
                 {
                     // We didn't already have a header set, so add a new one.
@@ -6123,7 +6123,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 // The header was not one of the "known" headers.
                 // Convert value to string first, because passing two spans causes 8 bytes stack zeroing in 
                 // this method with rep stosd, which is slower than necessary.
-                var valueStr = value.GetRequestHeaderStringNonNullCharacters(_useLatin1);
+                var valueStr = value.GetRequestHeaderStringNonNullCharacters(UseLatin1);
                 AppendUnknownHeaders(name, valueStr);
             }
         }

src/Servers/Kestrel/Core/src/Internal/Http/HttpProtocol.cs

@@ -8,6 +8,7 @@ using System.IO;
 using System.IO.Pipelines;
 using System.Linq;
 using System.Net;
+using System.Net.Http.Headers;
 using System.Runtime.CompilerServices;
 using System.Text;
 using System.Threading;
@@ -81,14 +82,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 
             ServerOptions = ServiceContext.ServerOptions;
 
-            HttpRequestHeaders = new HttpRequestHeaders(
-                reuseHeaderValues: !ServerOptions.DisableStringReuse,
-                useLatin1: ServerOptions.Latin1RequestHeaders);
-
             Reset();
 
-            HttpRequestHeaders.ReuseHeaderValues = !ServerOptions.DisableStringReuse;
-
             HttpResponseControl = this;
         }
 
@@ -371,6 +366,8 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
             ConnectionIdFeature = ConnectionId;
 
             HttpRequestHeaders.Reset();
+            HttpRequestHeaders.UseLatin1 = ServerOptions.Latin1RequestHeaders;
+            HttpRequestHeaders.ReuseHeaderValues = !ServerOptions.DisableStringReuse;
             HttpResponseHeaders.Reset();
             RequestHeaders = HttpRequestHeaders;
             ResponseHeaders = HttpResponseHeaders;

src/Servers/Kestrel/Core/src/Internal/Http/HttpRequestHeaders.cs

@@ -14,17 +14,17 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
 {
     internal sealed partial class HttpRequestHeaders : HttpHeaders
     {
-        private readonly bool _useLatin1;
         private long _previousBits = 0;
 
+        public bool ReuseHeaderValues { get; set; }
+        public bool UseLatin1 { get; set; }
+
         public HttpRequestHeaders(bool reuseHeaderValues = true, bool useLatin1 = false)
         {
             ReuseHeaderValues = reuseHeaderValues;
-            _useLatin1 = useLatin1;
+            UseLatin1 = useLatin1;
         }
 
-        public bool ReuseHeaderValues { get; set; }
-
         public void OnHeadersComplete()
         {
             var bitsToClear = _previousBits & ~_bits;
@@ -83,7 +83,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http
                 parsed < 0 ||
                 consumed != value.Length)
             {
-                BadHttpRequestException.Throw(RequestRejectionReason.InvalidContentLength, value.GetRequestHeaderStringNonNullCharacters(_useLatin1));
+                BadHttpRequestException.Throw(RequestRejectionReason.InvalidContentLength, value.GetRequestHeaderStringNonNullCharacters(UseLatin1));
             }
 
             _contentLength = parsed;

src/Servers/Kestrel/shared/KnownHeaders.cs

@@ -986,7 +986,7 @@ $@"        private void Clear(long bitsToClear)
                 }}
 
                 // We didn't have a previous matching header value, or have already added a header, so get the string for this value.
-                var valueStr = value.GetRequestHeaderStringNonNullCharacters(_useLatin1);
+                var valueStr = value.GetRequestHeaderStringNonNullCharacters(UseLatin1);
                 if ((_bits & flag) == 0)
                 {{
                     // We didn't already have a header set, so add a new one.
@@ -1004,7 +1004,7 @@ $@"        private void Clear(long bitsToClear)
                 // The header was not one of the ""known"" headers.
                 // Convert value to string first, because passing two spans causes 8 bytes stack zeroing in 
                 // this method with rep stosd, which is slower than necessary.
-                var valueStr = value.GetRequestHeaderStringNonNullCharacters(_useLatin1);
+                var valueStr = value.GetRequestHeaderStringNonNullCharacters(UseLatin1);
                 AppendUnknownHeaders(name, valueStr);
             }}
         }}" : "")}