Introduce header to customize surrogate key and reduce default size.

backend/src/Squidex.Web/Pipeline/CachingFilter.cs

@@ -33,42 +33,60 @@ namespace Squidex.Web.Pipeline
 
         public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
         {
-            var httpContext = context.HttpContext;
+            cachingManager.Start(context.HttpContext);
 
-            cachingManager.Start(httpContext);
-
-            cachingManager.AddHeader("Auth-State");
-
-            if (!string.IsNullOrWhiteSpace(httpContext.User.OpenIdSubject()))
-            {
-                cachingManager.AddHeader(HeaderNames.Authorization);
-            }
-            else if (!string.IsNullOrWhiteSpace(httpContext.User.OpenIdClientId()))
-            {
-                cachingManager.AddHeader("Auth-ClientId");
-            }
+            AppendAuthHeaders(context.HttpContext);
 
             var resultContext = await next();
 
-            if (httpContext.Response.Headers.TryGetString(HeaderNames.ETag, out var etag))
+            if (resultContext.HttpContext.Response.Headers.TryGetString(HeaderNames.ETag, out var etag))
             {
-                if (!cachingOptions.StrongETag && !etag.StartsWith("W/", StringComparison.OrdinalIgnoreCase))
+                if (!cachingOptions.StrongETag && IsWeakEtag(etag))
                 {
-                    etag = $"W/{etag}";
+                    etag = ToWeakEtag(etag);
 
-                    httpContext.Response.Headers[HeaderNames.ETag] = etag;
+                    resultContext.HttpContext.Response.Headers[HeaderNames.ETag] = etag;
                 }
 
-                if (HttpMethods.IsGet(httpContext.Request.Method) &&
-                    httpContext.Response.StatusCode == 200 &&
-                    httpContext.Request.Headers.TryGetString(HeaderNames.IfNoneMatch, out var noneMatch) &&
-                    string.Equals(etag, noneMatch, StringComparison.Ordinal))
+                if (IsCacheable(resultContext.HttpContext, etag))
                 {
                     resultContext.Result = new StatusCodeResult(304);
                 }
             }
 
-            cachingManager.Finish(httpContext);
+            cachingManager.Finish(resultContext.HttpContext);
+        }
+
+        private static bool IsCacheable(HttpContext httpContext, string etag)
+        {
+            return HttpMethods.IsGet(httpContext.Request.Method) &&
+                httpContext.Response.StatusCode == 200 &&
+                httpContext.Request.Headers.TryGetString(HeaderNames.IfNoneMatch, out var noneMatch) &&
+                string.Equals(etag, noneMatch, StringComparison.Ordinal);
+        }
+
+        private void AppendAuthHeaders(HttpContext httpContext)
+        {
+            cachingManager.AddHeader("Auth-State");
+
+            if (!string.IsNullOrWhiteSpace(httpContext.User.OpenIdSubject()))
+            {
+                cachingManager.AddHeader(HeaderNames.Authorization);
+            }
+            else if (!string.IsNullOrWhiteSpace(httpContext.User.OpenIdClientId()))
+            {
+                cachingManager.AddHeader("Auth-ClientId");
+            }
+        }
+
+        private static string ToWeakEtag(string? etag)
+        {
+            return $"W/{etag}";
+        }
+
+        private static bool IsWeakEtag(string etag)
+        {
+            return !etag.StartsWith("W/", StringComparison.OrdinalIgnoreCase);
         }
     }
 }

backend/src/Squidex.Web/Pipeline/CachingManager.cs

@@ -24,6 +24,8 @@ namespace Squidex.Web.Pipeline
 {
     public sealed class CachingManager : IRequestCache
     {
+        public const string SurrogateKeySizeHeader = "X-SurrogateKeys";
+        private const int MaxAllowedKeysSize = 20000;
         private readonly ObjectPool<StringBuilder> stringBuilderPool;
         private readonly CachingOptions cachingOptions;
         private readonly IHttpContextAccessor httpContextAccessor;
@@ -34,8 +36,14 @@ namespace Squidex.Web.Pipeline
             private readonly HashSet<string> keys = new HashSet<string>();
             private readonly HashSet<string> headers = new HashSet<string>();
             private readonly ReaderWriterLockSlim slimLock = new ReaderWriterLockSlim();
+            private readonly int maxKeysSize;
             private bool hasDependency;
 
+            public CacheContext(int maxKeysSize)
+            {
+                this.maxKeysSize = maxKeysSize;
+            }
+
             public void Dispose()
             {
                 hasher.Dispose();
@@ -87,7 +95,7 @@ namespace Squidex.Web.Pipeline
                 }
             }
 
-            public void Finish(HttpResponse response, int maxSurrogateKeySize, ObjectPool<StringBuilder> stringBuilderPool)
+            public void Finish(HttpResponse response, ObjectPool<StringBuilder> stringBuilderPool)
             {
                 if (hasDependency && !response.Headers.ContainsKey(HeaderNames.ETag))
                 {
@@ -100,10 +108,8 @@ namespace Squidex.Web.Pipeline
                     }
                 }
 
-                if (keys.Count > 0 && maxSurrogateKeySize > 0)
+                if (keys.Count > 0 && maxKeysSize > 0)
                 {
-                    const int GuidLength = 36;
-
                     var stringBuilder = stringBuilderPool.Get();
                     try
                     {
@@ -111,14 +117,14 @@ namespace Squidex.Web.Pipeline
                         {
                             if (stringBuilder.Length == 0)
                             {
-                                if (stringBuilder.Length + GuidLength > maxSurrogateKeySize)
+                                if (stringBuilder.Length + key.Length > maxKeysSize)
                                 {
                                     break;
                                 }
                             }
                             else
                             {
-                                if (stringBuilder.Length + GuidLength + 1 > maxSurrogateKeySize)
+                                if (stringBuilder.Length + key.Length + 1 > maxKeysSize)
                                 {
                                     break;
                                 }
@@ -183,7 +189,21 @@ namespace Squidex.Web.Pipeline
         {
             Guard.NotNull(httpContext);
 
-            httpContext.Features.Set(new CacheContext());
+            int maxKeysSize = GetKeysSize(httpContext);
+
+            httpContext.Features.Set(new CacheContext(maxKeysSize));
+        }
+
+        private int GetKeysSize(HttpContext httpContext)
+        {
+            var headers = httpContext.Request.Headers;
+
+            if (!headers.TryGetValue(SurrogateKeySizeHeader, out var header) || !int.TryParse(header, out int size))
+            {
+                size = cachingOptions.MaxSurrogateKeysSize;
+            }
+
+            return Math.Min(MaxAllowedKeysSize, size);
         }
 
         public void AddDependency(Guid key, long version)
@@ -233,7 +253,7 @@ namespace Squidex.Web.Pipeline
 
             if (cacheContext != null)
             {
-                cacheContext.Finish(httpContext.Response, cachingOptions.MaxSurrogateKeysSize, stringBuilderPool);
+                cacheContext.Finish(httpContext.Response, stringBuilderPool);
             }
         }
     }

backend/src/Squidex.Web/Pipeline/CachingOptions.cs

@@ -11,6 +11,6 @@ namespace Squidex.Web.Pipeline
     {
         public bool StrongETag { get; set; }
 
-        public int MaxSurrogateKeysSize { get; set; } = 17000;
+        public int MaxSurrogateKeysSize { get; set; } = 8000;
     }
 }

backend/src/Squidex/appsettings.json

@@ -39,7 +39,7 @@
     /*
      * Restrict the surrogate keys to 17KB.
      */
-    "maxSurrogateKeysSize": 17000
+    "maxSurrogateKeysSize": 8000
   },
 
   "languages": {

backend/tests/Squidex.Web.Tests/Pipeline/CachingFilterTests.cs

@@ -266,6 +266,25 @@ namespace Squidex.Web.Pipeline
             Assert.Equal(StringValues.Empty, httpContext.Response.Headers["Surrogate-Key"]);
         }
 
+        [Fact]
+        public async Task Should_not_append_surrogate_keys_if_maximum_is_overriden()
+        {
+            var id1 = Guid.NewGuid();
+            var id2 = Guid.NewGuid();
+
+            httpContext.Request.Headers[CachingManager.SurrogateKeySizeHeader] = "20";
+
+            await sut.OnActionExecutionAsync(executingContext, () =>
+            {
+                cachingManager.AddDependency(id1, 12);
+                cachingManager.AddDependency(id2, 12);
+
+                return Task.FromResult(executedContext);
+            });
+
+            Assert.Equal(StringValues.Empty, httpContext.Response.Headers["Surrogate-Key"]);
+        }
+
         [Fact]
         public async Task Should_generate_etag_from_ids_and_versions()
         {