Avoid some LINQ allocations (#2819)

Author: SimonCropp

src/Swashbuckle.AspNetCore.SwaggerGen/SchemaGenerator/MemberInfoExtensions.cs

@@ -85,9 +85,9 @@ public static bool IsDictionaryValueNonNullable(this MemberInfo memberInfo)
 
         private static object GetNullableAttribute(this MemberInfo memberInfo)
         {
-            var nullableAttribute = memberInfo.GetCustomAttributes()
-                .Where(attr => string.Equals(attr.GetType().FullName, NullableAttributeFullTypeName))
-                .FirstOrDefault();
+            var nullableAttribute = memberInfo
+                .GetCustomAttributes()
+                .FirstOrDefault(attr => string.Equals(attr.GetType().FullName, NullableAttributeFullTypeName));
 
             return nullableAttribute;
         }
@@ -103,8 +103,7 @@ private static bool GetNullableFallbackValue(this MemberInfo memberInfo)
                 var attributes = (IEnumerable<object>)declaringType.GetCustomAttributes(false);
 
                 var nullableContext = attributes
-                .Where(attr => string.Equals(attr.GetType().FullName, NullableContextAttributeFullTypeName))
-                .FirstOrDefault();
+                    .FirstOrDefault(attr => string.Equals(attr.GetType().FullName, NullableContextAttributeFullTypeName));
 
                 if (nullableContext != null)
                 {

src/Swashbuckle.AspNetCore.SwaggerGen/SwaggerGenerator/SwaggerGenerator.cs

@@ -86,9 +86,13 @@ public OpenApiDocument GetSwagger(string documentName, string host = null, strin
 
             var applicableApiDescriptions = _apiDescriptionsProvider.ApiDescriptionGroups.Items
                 .SelectMany(group => group.Items)
-                .Where(apiDesc => !(_options.IgnoreObsoleteActions && apiDesc.CustomAttributes().OfType<ObsoleteAttribute>().Any()))
-                .Where(apiDesc => !apiDesc.CustomAttributes().OfType<SwaggerIgnoreAttribute>().Any())
-                .Where(apiDesc => _options.DocInclusionPredicate(documentName, apiDesc));
+                .Where(apiDesc =>
+                {
+                    var attributes = apiDesc.CustomAttributes().ToList();
+                    return !(_options.IgnoreObsoleteActions && attributes.OfType<ObsoleteAttribute>().Any()) &&
+                           !attributes.OfType<SwaggerIgnoreAttribute>().Any() &&
+                           _options.DocInclusionPredicate(documentName, apiDesc);
+                });
 
             var schemaRepository = new SchemaRepository(documentName);
 

test/Swashbuckle.AspNetCore.TestSupport/ApiExplorer/ApiDescriptionFactory.cs

@@ -36,8 +36,7 @@ public static ApiDescription Create(
                     // If the provided action has a matching parameter - use it to assign ParameterDescriptor & ModelMetadata
                     parameter.ParameterDescriptor = actionDescriptor.Parameters
                         .OfType<ParameterDescriptor>()
-                        .Where(parameterDescriptor => parameterDescriptor.Name == parameter.Name)
-                        .FirstOrDefault();
+                        .FirstOrDefault(parameterDescriptor => parameterDescriptor.Name == parameter.Name);
 
                     var parameterDescriptorWithParameterInfo = parameter.ParameterDescriptor as
 #if NETCOREAPP2_2_OR_GREATER