Munch on less memory when handling property metadata

- #5499
- switch `foreach` to `for` and use less Linq when accessing `modelMetadata.Properties`
- change backing field for `ModelExplorer.Properties` from a list to an array

src/Microsoft.AspNetCore.Mvc.ApiExplorer/DefaultApiDescriptionProvider.cs

@@ -623,7 +623,7 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
                 //
                 if (modelMetadata.IsEnumerableType ||
                     !modelMetadata.IsComplexType ||
-                    !modelMetadata.Properties.Any())
+                    modelMetadata.Properties.Count == 0)
                 {
                     Context.Results.Add(CreateResult(bindingContext, source ?? ambientSource, containerName));
                     return;
@@ -656,10 +656,10 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
                     newContainerName = GetName(containerName, bindingContext);
                 }
 
-                foreach (var propertyMetadata in modelMetadata.Properties)
+                for (var i = 0; i < modelMetadata.Properties.Count; i++)
                 {
+                    var propertyMetadata = modelMetadata.Properties[i];
                     var key = new PropertyKey(propertyMetadata, source);
-
                     var propertyContext = ApiParameterDescriptionContext.GetContext(
                         propertyMetadata,
                         bindingInfo: null,

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/Binders/ComplexTypeModelBinder.cs

@@ -60,8 +60,9 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
                 bindingContext.Model = CreateModel(bindingContext);
             }
 
-            foreach (var property in bindingContext.ModelMetadata.Properties)
+            for (var i = 0; i < bindingContext.ModelMetadata.Properties.Count; i++)
             {
+                var property = bindingContext.ModelMetadata.Properties[i];
                 if (!CanBindProperty(bindingContext, property))
                 {
                     continue;
@@ -228,8 +229,9 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
             //
             var hasBindableProperty = false;
             var isAnyPropertyEnabledForValueProviderBasedBinding = false;
-            foreach (var propertyMetadata in bindingContext.ModelMetadata.Properties)
+            for (var i = 0; i < bindingContext.ModelMetadata.Properties.Count; i++)
             {
+                var propertyMetadata = bindingContext.ModelMetadata.Properties[i];
                 if (!CanBindProperty(bindingContext, propertyMetadata))
                 {
                     continue;

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/Binders/ComplexTypeModelBinderProvider.cs

@@ -2,8 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Reflection;
 using System.Collections.Generic;
+using System.Reflection;
 
 namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
 {
@@ -25,8 +25,9 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Binders
                 HasDefaultConstructor(context.Metadata.ModelType.GetTypeInfo()))
             {
                 var propertyBinders = new Dictionary<ModelMetadata, IModelBinder>();
-                foreach (var property in context.Metadata.Properties)
+                for (var i = 0; i < context.Metadata.Properties.Count; i++)
                 {
+                    var property = context.Metadata.Properties[i];
                     propertyBinders.Add(property, context.CreateBinder(property));
                 }
 

src/Microsoft.AspNetCore.Mvc.Core/ModelBinding/Internal/ModelBindingHelper.cs

@@ -463,8 +463,9 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding.Internal
                 }
                 else if (modelMetadata.IsComplexType)
                 {
-                    foreach (var property in modelMetadata.Properties)
+                    for (var i = 0; i < modelMetadata.Properties.Count; i++)
                     {
+                        var property = modelMetadata.Properties[i];
                         modelState.ClearValidationState(property.BinderModelName ?? property.PropertyName);
                     }
                 }

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ModelStateDictionaryExtensions.cs

@@ -129,9 +129,9 @@ namespace Microsoft.AspNetCore.Mvc.ModelBinding
             if (string.IsNullOrEmpty(modelKey))
             {
                 var modelMetadata = new EmptyModelMetadataProvider().GetMetadataForType(typeof(TModel));
-
-                foreach (var property in modelMetadata.Properties)
+                for (var i = 0; i < modelMetadata.Properties.Count; i++)
                 {
+                    var property = modelMetadata.Properties[i];
                     var childKey = property.BinderModelName ?? property.PropertyName;
                     var entries = modelState.FindKeysWithPrefix(childKey).ToArray();
                     foreach (var entry in entries)

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/ModelExplorer.cs

@@ -4,7 +4,6 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Linq;
 using Microsoft.AspNetCore.Mvc.ModelBinding;
 using Microsoft.Extensions.Internal;
 
@@ -20,7 +19,7 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
 
         private object _model;
         private Func<object, object> _modelAccessor;
-        private List<ModelExplorer> _properties;
+        private ModelExplorer[] _properties;
 
         /// <summary>
         /// Creates a new <see cref="ModelExplorer"/>.
@@ -198,24 +197,38 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
         /// Includes a <see cref="ModelExplorer"/> for each property of the <see cref="ModelMetadata"/>
         /// for <see cref="ModelType"/>.
         /// </remarks>
-        public IEnumerable<ModelExplorer> Properties
+        public IEnumerable<ModelExplorer> Properties => PropertiesInternal;
+
+        private ModelExplorer[] PropertiesInternal
         {
             get
             {
                 if (_properties == null)
                 {
-                    _properties = new List<ModelExplorer>();
-
                     var metadata = GetMetadataForRuntimeType();
+                    var properties = metadata.Properties;
+                    var propertyHelpers = PropertyHelper.GetProperties(ModelType);
 
-                    var properties = Enumerable.Join(
-                        metadata.Properties,
-                        PropertyHelper.GetProperties(ModelType),
-                        m => m.PropertyName,
-                        ph => ph.Property.Name,
-                        (m, ph) => CreateExplorerForProperty(m, ph));
+                    _properties = new ModelExplorer[properties.Count];
+                    for (var i = 0; i < properties.Count; i++)
+                    {
+                        var propertyMetadata = properties[i];
+                        PropertyHelper propertyHelper = null;
+                        for (var j = 0; j < propertyHelpers.Length; j++)
+                        {
+                            if (string.Equals(
+                                propertyMetadata.PropertyName,
+                                propertyHelpers[j].Property.Name,
+                                StringComparison.Ordinal))
+                            {
+                                propertyHelper = propertyHelpers[j];
+                                break;
+                            }
+                        }
 
-                    _properties.AddRange(properties);
+                        Debug.Assert(propertyHelper != null);
+                        _properties[i] = CreateExplorerForProperty(propertyMetadata, propertyHelper);
+                    }
                 }
 
                 return _properties;
@@ -252,10 +265,16 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures
                 throw new ArgumentNullException(nameof(name));
             }
 
-            return Properties.FirstOrDefault(p => string.Equals(
-                p.Metadata.PropertyName,
-                name,
-                StringComparison.Ordinal));
+            for (var i = 0; i < PropertiesInternal.Length; i++)
+            {
+                var property = PropertiesInternal[i];
+                if (string.Equals(name, property.Metadata.PropertyName, StringComparison.Ordinal))
+                {
+                    return property;
+                }
+            }
+
+            return null;
         }
 
         /// <summary>

src/Microsoft.AspNetCore.Mvc.ViewFeatures/ViewFeatures/ModelExplorerExtensions.cs

@@ -2,9 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
-using System.Linq;
 using System.Globalization;
-using Microsoft.AspNetCore.Mvc.ModelBinding;
+using System.Linq;
 
 namespace Microsoft.AspNetCore.Mvc.ViewFeatures
 {