From 1ed22e59390505f9e145371cdd0ac31e5692ac3e Mon Sep 17 00:00:00 2001
From: Ryan Nowak <nowakra@gmail.com>
Date: Sat, 3 Oct 2015 23:48:14 -0700
Subject: [PATCH] Avoid state machine and allocation for 0-parameters

---
 .../DefaultControllerActionArgumentBinder.cs  | 25 ++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.AspNet.Mvc.Core/Controllers/DefaultControllerActionArgumentBinder.cs b/src/Microsoft.AspNet.Mvc.Core/Controllers/DefaultControllerActionArgumentBinder.cs
index 7b7072c72d..5e3ed7a8ee 100644
--- a/src/Microsoft.AspNet.Mvc.Core/Controllers/DefaultControllerActionArgumentBinder.cs
+++ b/src/Microsoft.AspNet.Mvc.Core/Controllers/DefaultControllerActionArgumentBinder.cs
@@ -35,7 +35,7 @@ namespace Microsoft.AspNet.Mvc.Controllers
             _validator = validator;
         }
 
-        public async Task<IDictionary<string, object>> BindActionArgumentsAsync(
+        public Task<IDictionary<string, object>> BindActionArgumentsAsync(
             ActionContext actionContext,
             ActionBindingContext actionBindingContext,
             object controller)
@@ -64,6 +64,29 @@ namespace Microsoft.AspNet.Mvc.Controllers
                         nameof(actionContext));
             }
 
+            // Perf: Avoid allocating async state machines when we know there's nothing to bind.
+            if (actionDescriptor.BoundProperties.Count == 0 &&
+                actionDescriptor.Parameters.Count == 0)
+            {
+                return Task.FromResult<IDictionary<string, object>>(
+                    new Dictionary<string, object>(StringComparer.Ordinal));
+            }
+            else
+            {
+                return BindActionArgumentsCoreAsync(
+                    actionContext,
+                    actionBindingContext,
+                    controller,
+                    actionDescriptor);
+            }
+        }
+
+        private async Task<IDictionary<string, object>> BindActionArgumentsCoreAsync(
+            ActionContext actionContext,
+            ActionBindingContext actionBindingContext,
+            object controller,
+            ControllerActionDescriptor actionDescriptor)
+        {
             var operationBindingContext = GetOperationBindingContext(actionContext, actionBindingContext);
             var controllerProperties = new Dictionary<string, object>(StringComparer.Ordinal);
             await PopulateArgumentsAsync(