Added NoGCRegion feature

Author: Alex

Libraries/SPTarkov.Server.Assets/SPT_Data/configs/core.json

@@ -5,6 +5,9 @@
   "profileSaveIntervalSeconds": 15,
   "sptFriendNickname": "SPT",
   "allowProfileWipe": true,
+  "enableNoGCRegions": true,
+  "noGCRegionMaxMemoryGB": 4,
+  "noGCRegionMaxLOHMemoryGB": 3,
   "bsgLogging": {
     "verbosity": 6,
     "sendToServer": false

Libraries/SPTarkov.Server.Core/Models/Spt/Config/CoreConfig.cs

@@ -42,6 +42,44 @@ public record CoreConfig : BaseConfig
     [JsonPropertyName("features")]
     public required ServerFeatures Features { get; set; }
 
+    [JsonPropertyName("enableNoGCRegions")]
+    // ReSharper disable once InconsistentNaming
+    public required bool EnableNoGCRegions { get; set; }
+
+    // ReSharper disable once InconsistentNaming
+    private int _noGCRegionMaxMemoryGB = 4;
+    [JsonPropertyName("noGCRegionMaxMemoryGB")]
+    // ReSharper disable once InconsistentNaming
+    public required int NoGCRegionMaxMemoryGB
+    {
+        get => _noGCRegionMaxMemoryGB;
+        set
+        {
+            if (value <= 0)
+            {
+                throw new Exception($"Invalid value {nameof(NoGCRegionMaxMemoryGB)}: {value}. Must be greater than zero.");
+            }
+            _noGCRegionMaxMemoryGB = value;
+        }
+    }
+
+    // ReSharper disable once InconsistentNaming
+    private int _noGCRegionMaxLOHMemoryGB = 3;
+    [JsonPropertyName("noGCRegionMaxLOHMemoryGB")]
+    // ReSharper disable once InconsistentNaming
+    public required int NoGCRegionMaxLOHMemoryGB
+    {
+        get => _noGCRegionMaxLOHMemoryGB;
+        set
+        {
+            if (value <= 0)
+            {
+                throw new Exception($"Invalid value {nameof(NoGCRegionMaxLOHMemoryGB)}: {value}. Must be greater than zero.");
+            }
+            _noGCRegionMaxLOHMemoryGB = value;
+        }
+    }
+
     /// <summary>
     ///     Commit hash build server was created from
     /// </summary>

SPTarkov.Server/Program.cs

@@ -1,5 +1,6 @@
 using System.Net;
 using System.Net.Sockets;
+using System.Runtime;
 using System.Runtime.InteropServices;
 using System.Security.Authentication;
 using System.Text;
@@ -118,6 +119,8 @@ public static async Task StartServer(string[] args)
             forwardedHeadersOptions.KnownProxies.Clear();
             app.UseForwardedHeaders(forwardedHeadersOptions);
 
+            app.UseRequestTracking();
+
             SetConsoleOutputMode();
 
             await app.Services.GetRequiredService<SptServerStartupService>().Startup();
@@ -147,14 +150,52 @@ private static void ConfigureWebApp(WebApplication app)
 
         app.UseMiddleware<SptLoggerMiddleware>();
 
-        app.Use(
-            async (HttpContext context, RequestDelegate next) =>
+        app.Use(async (context, next) => await HandleRequest(context, next));
+
+        app.UseSptBlazor();
+    }
+
+    private static async Task HandleRequest(HttpContext context, RequestDelegate next)
+    {
+        var config = context.RequestServices.GetRequiredService<ConfigServer>().GetConfig<CoreConfig>();
+
+        // if no other requests are running, start the no GC region, otherwise dont start it
+        if (!RequestTrackingMiddleware.OtherRequestsActive)
+        {
+            if (config.EnableNoGCRegions && GCSettings.LatencyMode != GCLatencyMode.NoGCRegion)
             {
-                await context.RequestServices.GetRequiredService<HttpServer>().HandleRequest(context, next);
+                try
+                {
+                    GC.TryStartNoGCRegion(
+                        1024L * 1024L * 1024L * config.NoGCRegionMaxMemoryGB,
+                        1024L * 1024L * 1024L * config.NoGCRegionMaxLOHMemoryGB,
+                        true
+                    );
+                }
+                catch (Exception)
+                {
+                    // ignored, we keep going
+                }
             }
-        );
+        }
 
-        app.UseSptBlazor();
+        await context.RequestServices.GetRequiredService<HttpServer>().HandleRequest(context, next);
+
+        // if no other requests are running, end the no GC region, otherwise dont stop it as other requests need it still
+        if (!RequestTrackingMiddleware.OtherRequestsActive)
+        {
+            if (config.EnableNoGCRegions && GCSettings.LatencyMode == GCLatencyMode.NoGCRegion)
+            {
+                try
+                {
+                    GC.EndNoGCRegion();
+                }
+                catch (Exception)
+                {
+                    // ignored, we dont care about handling this
+                }
+            }
+        }
     }
 
     private static void ConfigureKestrel(WebApplicationBuilder builder)

SPTarkov.Server/Services/RequestTrackingMiddleware.cs

@@ -0,0 +1,41 @@
+namespace SPTarkov.Server.Services;
+
+public class RequestTrackingMiddleware
+{
+    private static int _activeRequests;
+    private readonly RequestDelegate _next;
+
+    public static bool OtherRequestsActive
+    {
+        get
+        {
+            return _activeRequests > 1;
+        }
+    }
+
+    public RequestTrackingMiddleware(RequestDelegate next)
+    {
+        _next = next;
+    }
+
+    public async Task InvokeAsync(HttpContext context)
+    {
+        Interlocked.Increment(ref _activeRequests);
+        try
+        {
+            await _next(context);
+        }
+        finally
+        {
+            Interlocked.Decrement(ref _activeRequests);
+        }
+    }
+}
+
+public static class RequestTrackingMiddlewareExtensions
+{
+    public static IApplicationBuilder UseRequestTracking(this IApplicationBuilder builder)
+    {
+        return builder.UseMiddleware<RequestTrackingMiddleware>();
+    }
+}