Reduce per-request allocations in middleware hot path (#345)

Author: SimonCropp

readme.md

@@ -136,7 +136,7 @@ internal static string BuildEtag(string timeStamp, string? suffix)
     return $"\"{AssemblyWriteTime}-{timeStamp}-{suffix}\"";
 }
 ```
-<sup><a href='/src/Delta/DeltaExtensions_Shared.cs#L183-L195' title='Snippet source file'>snippet source</a> | <a href='#snippet-BuildEtag' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Delta/DeltaExtensions_Shared.cs#L182-L194' title='Snippet source file'>snippet source</a> | <a href='#snippet-BuildEtag' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 

src/Delta.EF/DeltaExtensions_EFMiddleware.cs

@@ -6,10 +6,14 @@ public static IApplicationBuilder UseDelta<TDbContext>(this IApplicationBuilder
         where TDbContext : DbContext
     {
         var logger = builder.ApplicationServices.GetLogger();
+
+        static Task<string> GetTimeStamp(HttpContext context) =>
+            context.RequestServices.GetRequiredService<TDbContext>().GetLastTimeStamp();
+
         return builder.Use(
             async (context, next) =>
             {
-                if (await HandleRequest<TDbContext>(context, logger, suffix, shouldExecute, logLevel, allowAnonymous))
+                if (await HandleRequest(context, logger, suffix, GetTimeStamp, shouldExecute, logLevel, allowAnonymous))
                 {
                     return;
                 }
@@ -24,9 +28,13 @@ static TBuilder UseDelta<TBuilder, TDbContext>(this TBuilder builder, Func<HttpC
         builder.AddEndpointFilterFactory((filterContext, next) =>
         {
             var logger = filterContext.ApplicationServices.GetLogger();
+
+            static Task<string> GetTimeStamp(HttpContext context) =>
+                context.RequestServices.GetRequiredService<TDbContext>().GetLastTimeStamp();
+
             return async invocationContext =>
             {
-                if (await HandleRequest<TDbContext>(invocationContext.HttpContext, logger, suffix, shouldExecute, logLevel, allowAnonymous))
+                if (await HandleRequest(invocationContext.HttpContext, logger, suffix, GetTimeStamp, shouldExecute, logLevel, allowAnonymous))
                 {
                     return Results.Empty;
                 }
@@ -35,19 +43,6 @@ static TBuilder UseDelta<TBuilder, TDbContext>(this TBuilder builder, Func<HttpC
             };
         });
 
-    static Task<bool> HandleRequest<T>(HttpContext context, ILogger logger, Func<HttpContext, string?>? suffix, Func<HttpContext, bool>? shouldExecute, LogLevel logLevel, bool allowAnonymous = false)
-        where T : DbContext =>
-        HandleRequest(
-            context,
-            logger,
-            suffix,
-            _ => _.RequestServices
-                .GetRequiredService<T>()
-                .GetLastTimeStamp(),
-            shouldExecute,
-            logLevel,
-            allowAnonymous);
-
     public static Task<string> GetLastTimeStamp(this DbContext context, Cancel cancel = default)
     {
         var database = context.Database;

src/Delta/DeltaExtensions_Middleware.cs

@@ -6,10 +6,17 @@ public static IApplicationBuilder UseDelta(this IApplicationBuilder builder, Get
     {
         getConnection ??= DiscoverConnection;
         var logger = builder.ApplicationServices.GetLogger();
+
+        Task<string> GetTimeStamp(HttpContext context)
+        {
+            var (connection, transaction) = getConnection(context);
+            return connection.GetLastTimeStamp(transaction);
+        }
+
         return builder.Use(
             async (context, next) =>
             {
-                if (await HandleRequest(context, getConnection, logger, suffix, shouldExecute, logLevel, allowAnonymous))
+                if (await HandleRequest(context, logger, suffix, GetTimeStamp, shouldExecute, logLevel, allowAnonymous))
                 {
                     return;
                 }
@@ -26,9 +33,16 @@ static TBuilder UseDelta<TBuilder>(this TBuilder builder, GetConnection? getConn
         return builder.AddEndpointFilterFactory((filterContext, next) =>
         {
             var logger = filterContext.ApplicationServices.GetLogger();
+
+            Task<string> GetTimeStamp(HttpContext context)
+            {
+                var (connection, transaction) = getConnection(context);
+                return connection.GetLastTimeStamp(transaction);
+            }
+
             return async invocationContext =>
             {
-                if (await HandleRequest(invocationContext.HttpContext, getConnection, logger, suffix, shouldExecute, logLevel, allowAnonymous))
+                if (await HandleRequest(invocationContext.HttpContext, logger, suffix, GetTimeStamp, shouldExecute, logLevel, allowAnonymous))
                 {
                     return Results.Empty;
                 }
@@ -38,27 +52,6 @@ static TBuilder UseDelta<TBuilder>(this TBuilder builder, GetConnection? getConn
         });
     }
 
-    static Task<bool> HandleRequest(
-        HttpContext context,
-        GetConnection getConnection,
-        ILogger logger,
-        Func<HttpContext, string?>? suffix,
-        Func<HttpContext, bool>? shouldExecute,
-        LogLevel logLevel,
-        bool allowAnonymous = false) =>
-        HandleRequest(
-            context,
-            logger,
-            suffix,
-            _ =>
-            {
-                var (connection, transaction) = getConnection(_);
-                return connection.GetLastTimeStamp(transaction);
-            },
-            shouldExecute,
-            logLevel,
-            allowAnonymous);
-
     public static ComponentEndpointConventionBuilder UseDelta(
         this ComponentEndpointConventionBuilder builder,
         GetConnection? getConnection = null,

src/Delta/DeltaExtensions_Shared.cs

@@ -60,10 +60,9 @@ internal static async Task<bool> HandleRequest(HttpContext context, ILogger logg
         var path = request.Path;
 
         var logEnabled = logger.IsEnabled(level);
-        var method = request.Method;
-        if (method != "GET")
+        if (!HttpMethods.IsGet(request.Method))
         {
-            WriteNo304Header(response, $"Request Method={method}", level, logger, path, logEnabled);
+            WriteNo304Header(response, "Request method is not GET", level, logger, path, logEnabled);
             return false;
         }
 
@@ -123,7 +122,7 @@ Ensure authentication middleware runs before UseDelta so that User claims are av
             }
             else
             {
-                reason = $"Request has no If-None-Match. Request also has Cache-Control header ({cacheControl}) which can interfere with caching";
+                reason = "Request has no If-None-Match. Request Cache-Control header may interfere with caching";
             }
 
             WriteNo304Header(response, reason, level, logger, path, logEnabled);

src/DeltaTests/MiddlewareTests.Combinations_suffixFunc=False_nullSuffixFunc=False_get=False_ifNoneMatch=False_sameIfNoneMatch=False_etag=False_executeFunc=False_trueExecuteFunc=False_immutable=False_requestCacheControl=False.verified.txt

@@ -1,24 +1,24 @@
-{
+{
   target: {
     notModified: false,
     context: {
       Request: {},
       Response: {
         StatusCode: OK,
         Headers: {
-          Delta-No304: Request Method=POST
+          Delta-No304: Request method is not GET
         }
       }
     }
   },
   log: {
-    Information: Delta /path: No 304. Request Method=POST,
+    Information: Delta /path: No 304. Request method is not GET,
     State: [
       {
         path: /path
       },
       {
-        reason: Request Method=POST
+        reason: Request method is not GET
       },
       {
         {OriginalFormat}: Delta {path}: No 304. {reason}

src/DeltaTests/MiddlewareTests.Combinations_suffixFunc=False_nullSuffixFunc=False_get=False_ifNoneMatch=False_sameIfNoneMatch=False_etag=False_executeFunc=False_trueExecuteFunc=False_immutable=False_requestCacheControl=True.verified.txt

@@ -1,4 +1,4 @@
-{
+{
   target: {
     notModified: false,
     context: {
@@ -10,19 +10,19 @@
       Response: {
         StatusCode: OK,
         Headers: {
-          Delta-No304: Request Method=POST
+          Delta-No304: Request method is not GET
         }
       }
     }
   },
   log: {
-    Information: Delta /path: No 304. Request Method=POST,
+    Information: Delta /path: No 304. Request method is not GET,
     State: [
       {
         path: /path
       },
       {
-        reason: Request Method=POST
+        reason: Request method is not GET
       },
       {
         {OriginalFormat}: Delta {path}: No 304. {reason}

src/DeltaTests/MiddlewareTests.Combinations_suffixFunc=False_nullSuffixFunc=False_get=False_ifNoneMatch=False_sameIfNoneMatch=False_etag=False_executeFunc=False_trueExecuteFunc=False_immutable=True_requestCacheControl=False.verified.txt

@@ -1,4 +1,4 @@
-{
+{
   target: {
     notModified: false,
     context: {
@@ -7,19 +7,19 @@
         StatusCode: OK,
         Headers: {
           Cache-Control: public, max-age=31536000, immutable,
-          Delta-No304: Request Method=POST
+          Delta-No304: Request method is not GET
         }
       }
     }
   },
   log: {
-    Information: Delta /path: No 304. Request Method=POST,
+    Information: Delta /path: No 304. Request method is not GET,
     State: [
       {
         path: /path
       },
       {
-        reason: Request Method=POST
+        reason: Request method is not GET
       },
       {
         {OriginalFormat}: Delta {path}: No 304. {reason}

src/DeltaTests/MiddlewareTests.Combinations_suffixFunc=False_nullSuffixFunc=False_get=False_ifNoneMatch=False_sameIfNoneMatch=False_etag=False_executeFunc=False_trueExecuteFunc=False_immutable=True_requestCacheControl=True.verified.txt

@@ -1,4 +1,4 @@
-{
+{
   target: {
     notModified: false,
     context: {
@@ -11,19 +11,19 @@
         StatusCode: OK,
         Headers: {
           Cache-Control: public, max-age=31536000, immutable,
-          Delta-No304: Request Method=POST
+          Delta-No304: Request method is not GET
         }
       }
     }
   },
   log: {
-    Information: Delta /path: No 304. Request Method=POST,
+    Information: Delta /path: No 304. Request method is not GET,
     State: [
       {
         path: /path
       },
       {
-        reason: Request Method=POST
+        reason: Request method is not GET
       },
       {
         {OriginalFormat}: Delta {path}: No 304. {reason}

src/DeltaTests/MiddlewareTests.Combinations_suffixFunc=False_nullSuffixFunc=False_get=False_ifNoneMatch=False_sameIfNoneMatch=False_etag=False_executeFunc=False_trueExecuteFunc=True_immutable=False_requestCacheControl=False.verified.txt

@@ -1,24 +1,24 @@
-{
+{
   target: {
     notModified: false,
     context: {
       Request: {},
       Response: {
         StatusCode: OK,
         Headers: {
-          Delta-No304: Request Method=POST
+          Delta-No304: Request method is not GET
         }
       }
     }
   },
   log: {
-    Information: Delta /path: No 304. Request Method=POST,
+    Information: Delta /path: No 304. Request method is not GET,
     State: [
       {
         path: /path
       },
       {
-        reason: Request Method=POST
+        reason: Request method is not GET
       },
       {
         {OriginalFormat}: Delta {path}: No 304. {reason}

src/DeltaTests/MiddlewareTests.Combinations_suffixFunc=False_nullSuffixFunc=False_get=False_ifNoneMatch=False_sameIfNoneMatch=False_etag=False_executeFunc=False_trueExecuteFunc=True_immutable=False_requestCacheControl=True.verified.txt

@@ -1,4 +1,4 @@
-{
+{
   target: {
     notModified: false,
     context: {
@@ -10,19 +10,19 @@
       Response: {
         StatusCode: OK,
         Headers: {
-          Delta-No304: Request Method=POST
+          Delta-No304: Request method is not GET
         }
       }
     }
   },
   log: {
-    Information: Delta /path: No 304. Request Method=POST,
+    Information: Delta /path: No 304. Request method is not GET,
     State: [
       {
         path: /path
       },
       {
-        reason: Request Method=POST
+        reason: Request method is not GET
       },
       {
         {OriginalFormat}: Delta {path}: No 304. {reason}