More read interface IList.Count once rather than per iteration + miscellany (#11253)

* Read interface IList.Count once rather than per iteration

Inspired by #9962, read .Count once rather than once per loop iteration.

* Use nameof() instead of ToString()

Use constant nameof() on enum value, rather than runtime ToString().

* Right-size dictionary

Initialize dictionary with a fixed number of elements to the number of elements it contains.

* Use DisposeAsync()

Use DisposeAsync() on FileBufferingReadStream in input formatters.

* Override DisposeAsync()

Override DisposeAsync() to call DisposeAsync() on the inner stream.

* Use GetValueOrDefault() for content-length

Use GetValueOrDefault() to read the content length once instead of checking HasValue once and Value up to three times.

* Update Microsoft.AspNetCore.WebUtilities.netcoreapp3.0.cs

Add DisposeAsync().

* Use DisposeAsync()

Use DisposeAsync() on transcoding streams as other formatters do.

src/Http/WebUtilities/ref/Microsoft.AspNetCore.WebUtilities.netcoreapp3.0.cs

@@ -54,6 +54,8 @@ namespace Microsoft.AspNetCore.WebUtilities
         public override long Position { get { throw null; } set { } }
         public string TempFileName { get { throw null; } }
         protected override void Dispose(bool disposing) { }
+        [System.Diagnostics.DebuggerStepThroughAttribute]
+        public override System.Threading.Tasks.ValueTask DisposeAsync() { throw null; }
         public override void Flush() { }
         public override int Read(byte[] buffer, int offset, int count) { throw null; }
         [System.Diagnostics.DebuggerStepThroughAttribute]

src/Http/WebUtilities/src/FileBufferingReadStream.cs

@@ -366,6 +366,20 @@ namespace Microsoft.AspNetCore.WebUtilities
             }
         }
 
+        public async override ValueTask DisposeAsync()
+        {
+            if (!_disposed)
+            {
+                _disposed = true;
+                if (_rentedBuffer != null)
+                {
+                    _bytePool.Return(_rentedBuffer);
+                }
+
+                await _buffer.DisposeAsync();
+            }
+        }
+
         private void ThrowIfDisposed()
         {
             if (_disposed)

src/Mvc/Mvc.ApiExplorer/src/DefaultApiDescriptionProvider.cs

@@ -569,9 +569,11 @@ namespace Microsoft.AspNetCore.Mvc.ApiExplorer
                     newContainerName = GetName(containerName, bindingContext);
                 }
 
-                for (var i = 0; i < modelMetadata.Properties.Count; i++)
+                var metadataProperties = modelMetadata.Properties;
+                var metadataPropertiesCount = metadataProperties.Count;
+                for (var i = 0; i < metadataPropertiesCount; i++)
                 {
-                    var propertyMetadata = modelMetadata.Properties[i];
+                    var propertyMetadata = metadataProperties[i];
                     var key = new PropertyKey(propertyMetadata, source);
                     var bindingInfo = BindingInfo.GetBindingInfo(Enumerable.Empty<object>(), propertyMetadata);
 

src/Mvc/Mvc.Core/src/Formatters/SystemTextJsonInputFormatter.cs

@@ -71,7 +71,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             {
                 if (inputStream is TranscodingReadStream transcoding)
                 {
-                    transcoding.Dispose();
+                    await transcoding.DisposeAsync();
                 }
             }
 

src/Mvc/Mvc.Core/src/Formatters/SystemTextJsonOutputFormatter.cs

@@ -66,7 +66,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             {
                 if (writeStream is TranscodingWriteStream transcoding)
                 {
-                    transcoding.Dispose();
+                    await transcoding.DisposeAsync();
                 }
             }
         }

src/Mvc/Mvc.Cors/src/CorsApplicationModelProvider.cs

@@ -97,15 +97,22 @@ namespace Microsoft.AspNetCore.Mvc.Cors
 
         private static void ConfigureCorsActionConstraint(ActionModel actionModel)
         {
-            for (var i = 0; i < actionModel.Selectors.Count; i++)
-            {
-                var selectorModel = actionModel.Selectors[i];
+            var selectors = actionModel.Selectors;
+            // Read interface .Count once rather than per iteration
+            var selectorsCount = selectors.Count;
 
-                for (var j = 0; j < selectorModel.ActionConstraints.Count; j++)
+            for (var i = 0; i < selectorsCount; i++)
+            {
+                var selectorModel = selectors[i];
+
+                var actionConstraints = selectorModel.ActionConstraints;
+                // Read interface .Count once rather than per iteration
+                var actionConstraintsCount = actionConstraints.Count;
+                for (var j = 0; j < actionConstraintsCount; j++)
                 {
-                    if (selectorModel.ActionConstraints[j] is HttpMethodActionConstraint httpConstraint)
+                    if (actionConstraints[j] is HttpMethodActionConstraint httpConstraint)
                     {
-                        selectorModel.ActionConstraints[j] = new CorsHttpMethodActionConstraint(httpConstraint);
+                        actionConstraints[j] = new CorsHttpMethodActionConstraint(httpConstraint);
                     }
                 }
             }
@@ -131,11 +138,14 @@ namespace Microsoft.AspNetCore.Mvc.Cors
 
                     foreach (var selector in action.Selectors)
                     {
-                        for (var i = 0; i < selector.EndpointMetadata.Count; i++)
+                        var metadata = selector.EndpointMetadata;
+                        // Read interface .Count once rather than per iteration
+                        var metadataCount = metadata.Count;
+                        for (var i = 0; i < metadataCount; i++)
                         {
-                            if (selector.EndpointMetadata[i] is HttpMethodMetadata httpMethodMetadata)
+                            if (metadata[i] is HttpMethodMetadata httpMethodMetadata)
                             {
-                                selector.EndpointMetadata[i] = new HttpMethodMetadata(httpMethodMetadata.HttpMethods, acceptCorsPreflight: true);
+                                metadata[i] = new HttpMethodMetadata(httpMethodMetadata.HttpMethods, acceptCorsPreflight: true);
                             }
                         }
                     }

src/Mvc/Mvc.Cors/src/CorsHttpMethodActionConstraint.cs

@@ -39,7 +39,9 @@ namespace Microsoft.AspNetCore.Mvc.Cors
                 request.Headers.TryGetValue(AccessControlRequestMethod, out var accessControlRequestMethod) &&
                 !StringValues.IsNullOrEmpty(accessControlRequestMethod))
             {
-                for (var i = 0; i < methods.Count; i++)
+                // Read interface .Count once rather than per iteration
+                var methodsCount = methods.Count;
+                for (var i = 0; i < methodsCount; i++)
                 {
                     var supportedMethod = methods[i];
                     if (string.Equals(supportedMethod, accessControlRequestMethod, StringComparison.OrdinalIgnoreCase))

src/Mvc/Mvc.DataAnnotations/src/DataAnnotationsClientModelValidatorProvider.cs

@@ -67,9 +67,12 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
 
             var hasRequiredAttribute = false;
 
-            for (var i = 0; i < context.Results.Count; i++)
+            var results = context.Results;
+            // Read interface .Count once rather than per iteration
+            var resultsCount = results.Count;
+            for (var i = 0; i < resultsCount; i++)
             {
-                var validatorItem = context.Results[i];
+                var validatorItem = results[i];
                 if (validatorItem.Validator != null)
                 {
                     // Check if a required attribute is already cached.

src/Mvc/Mvc.DataAnnotations/src/DataAnnotationsMetadataProvider.cs

@@ -109,7 +109,7 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
             }
             else if (displayFormatAttribute != null && !displayFormatAttribute.HtmlEncode)
             {
-                displayMetadata.DataTypeName = DataType.Html.ToString();
+                displayMetadata.DataTypeName = nameof(DataType.Html);
             }
 
             var containerType = context.Key.ContainerType ?? context.Key.ModelType;
@@ -322,11 +322,14 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
                 throw new ArgumentNullException(nameof(context));
             }
 
-            var attributes = new List<object>(context.Attributes.Count);
-
-            for (var i = 0; i < context.Attributes.Count; i++)
+            // Read interface .Count once rather than per iteration
+            var contextAttributes = context.Attributes;
+            var contextAttributesCount = contextAttributes.Count;
+            var attributes = new List<object>(contextAttributesCount);
+            
+            for (var i = 0; i < contextAttributesCount; i++)
             {
-                var attribute = context.Attributes[i];
+                var attribute = contextAttributes[i];
                 if (attribute is ValidationProviderAttribute validationProviderAttribute)
                 {
                     attributes.AddRange(validationProviderAttribute.GetValidationAttributes());

src/Mvc/Mvc.DataAnnotations/src/DataAnnotationsModelValidatorProvider.cs

@@ -59,9 +59,12 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
                     _stringLocalizerFactory);
             }
 
-            for (var i = 0; i < context.Results.Count; i++)
+            var results = context.Results;
+            // Read interface .Count once rather than per iteration
+            var resultsCount = results.Count;
+            for (var i = 0; i < resultsCount; i++)
             {
-                var validatorItem = context.Results[i];
+                var validatorItem = results[i];
                 if (validatorItem.Validator != null)
                 {
                     continue;
@@ -106,7 +109,9 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
                 return true;
             }
 
-            for (var i = 0; i < validatorMetadata.Count; i++)
+            // Read interface .Count once rather than per iteration
+            var validatorMetadataCount = validatorMetadata.Count;
+            for (var i = 0; i < validatorMetadataCount; i++)
             {
                 if (validatorMetadata[i] is ValidationAttribute)
                 {

src/Mvc/Mvc.DataAnnotations/src/DefaultClientModelValidatorProvider.cs

@@ -24,9 +24,11 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
             }
 
             // Perf: Avoid allocations
-            for (var i = 0; i < context.Results.Count; i++)
+            var results = context.Results;
+            var resultsCount = results.Count;
+            for (var i = 0; i < resultsCount; i++)
             {
-                var validatorItem = context.Results[i];
+                var validatorItem = results[i];
                 // Don't overwrite anything that was done by a previous provider.
                 if (validatorItem.Validator != null)
                 {

src/Mvc/Mvc.DataAnnotations/src/NumericClientModelValidatorProvider.cs

@@ -27,9 +27,12 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
                 typeToValidate == typeof(double) ||
                 typeToValidate == typeof(decimal))
             {
-                for (var i = 0; i < context.Results.Count; i++)
+                var results = context.Results;
+                // Read interface .Count once rather than per iteration
+                var resultsCount = results.Count;
+                for (var i = 0; i < resultsCount; i++)
                 {
-                    var validator = context.Results[i].Validator;
+                    var validator = results[i].Validator;
                     if (validator != null && validator is NumericClientModelValidator)
                     {
                         // A validator is already present. No need to add one.
@@ -37,7 +40,7 @@ namespace Microsoft.AspNetCore.Mvc.DataAnnotations
                     }
                 }
 
-                context.Results.Add(new ClientValidatorItem
+                results.Add(new ClientValidatorItem
                 {
                     Validator = new NumericClientModelValidator(),
                     IsReusable = true

src/Mvc/Mvc.Formatters.Xml/src/XmlDataContractSerializerInputFormatter.cs

@@ -124,10 +124,11 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
                 // XmlDataContractSerializer does synchronous reads. In order to avoid blocking on the stream, we asynchronously
                 // read everything into a buffer, and then seek back to the beginning.
                 var memoryThreshold = DefaultMemoryThreshold;
-                if (request.ContentLength.HasValue && request.ContentLength.Value > 0 && request.ContentLength.Value < memoryThreshold)
+                var contentLength = request.ContentLength.GetValueOrDefault();
+                if (contentLength > 0 && contentLength < memoryThreshold)
                 {
                     // If the Content-Length is known and is smaller than the default buffer size, use it.
-                    memoryThreshold = (int)request.ContentLength.Value;
+                    memoryThreshold = (int)contentLength;
                 }
 
                 readStream = new FileBufferingReadStream(request.Body, memoryThreshold);
@@ -163,7 +164,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             {
                 if (readStream is FileBufferingReadStream fileBufferingReadStream)
                 {
-                    fileBufferingReadStream.Dispose();
+                    await fileBufferingReadStream.DisposeAsync();
                 }
             }
         }

src/Mvc/Mvc.Formatters.Xml/src/XmlSerializerInputFormatter.cs

@@ -104,10 +104,11 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
                 // XmlSerializer does synchronous reads. In order to avoid blocking on the stream, we asynchronously
                 // read everything into a buffer, and then seek back to the beginning.
                 var memoryThreshold = DefaultMemoryThreshold;
-                if (request.ContentLength.HasValue && request.ContentLength.Value > 0 && request.ContentLength.Value < memoryThreshold)
+                var contentLength = request.ContentLength.GetValueOrDefault();
+                if (contentLength > 0 && contentLength < memoryThreshold)
                 {
                     // If the Content-Length is known and is smaller than the default buffer size, use it.
-                    memoryThreshold = (int)request.ContentLength.Value;
+                    memoryThreshold = (int)contentLength;
                 }
 
                 readStream = new FileBufferingReadStream(request.Body, memoryThreshold);
@@ -156,7 +157,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             {
                 if (readStream is FileBufferingReadStream fileBufferingReadStream)
                 {
-                    fileBufferingReadStream.Dispose();
+                    await fileBufferingReadStream.DisposeAsync();
                 }
             }
         }

src/Mvc/Mvc.NewtonsoftJson/src/BsonTempDataSerializer.cs

@@ -31,7 +31,7 @@ namespace Microsoft.AspNetCore.Mvc.NewtonsoftJson
         private static readonly ConcurrentDictionary<Type, Func<JObject, object>> _dictionaryConverters =
             new ConcurrentDictionary<Type, Func<JObject, object>>();
 
-        private static readonly Dictionary<JTokenType, Type> _tokenTypeLookup = new Dictionary<JTokenType, Type>
+        private static readonly Dictionary<JTokenType, Type> _tokenTypeLookup = new Dictionary<JTokenType, Type>(8)
         {
             { JTokenType.String, typeof(string) },
             { JTokenType.Integer, typeof(int) },

src/Mvc/Mvc.NewtonsoftJson/src/NewtonsoftJsonInputFormatter.cs

@@ -134,10 +134,11 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
                 // JSON.Net does synchronous reads. In order to avoid blocking on the stream, we asynchronously
                 // read everything into a buffer, and then seek back to the beginning.
                 var memoryThreshold = DefaultMemoryThreshold;
-                if (request.ContentLength.HasValue && request.ContentLength.Value > 0 && request.ContentLength.Value < memoryThreshold)
+                var contentLength = request.ContentLength.GetValueOrDefault();
+                if (contentLength > 0 && contentLength < memoryThreshold)
                 {
                     // If the Content-Length is known and is smaller than the default buffer size, use it.
-                    memoryThreshold = (int)request.ContentLength.Value;
+                    memoryThreshold = (int)contentLength;
                 }
 
                 readStream = new FileBufferingReadStream(request.Body, memoryThreshold);
@@ -171,7 +172,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
                     if (readStream is FileBufferingReadStream fileBufferingReadStream)
                     {
-                        fileBufferingReadStream.Dispose();
+                        await fileBufferingReadStream.DisposeAsync();
                     }
                 }
             }