From 67c8e9bc0e9528d0a38ba837ff7cddeb265ba5d2 Mon Sep 17 00:00:00 2001
From: Neil Bostrom <github@silvergames.net>
Date: Tue, 14 May 2019 22:44:35 +0100
Subject: [PATCH] Refactored GetConstraints to use IEnumerable to reduce
 allocations

Also made configurationSource a private field
---
 .../RelationalEntityTypeExtensions.cs         |  2 +-
 .../Metadata/Internal/CheckConstraint.cs      | 22 +++++++------------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/src/EFCore.Relational/Extensions/RelationalEntityTypeExtensions.cs b/src/EFCore.Relational/Extensions/RelationalEntityTypeExtensions.cs
index bf06d89607b..313b98e7318 100644
--- a/src/EFCore.Relational/Extensions/RelationalEntityTypeExtensions.cs
+++ b/src/EFCore.Relational/Extensions/RelationalEntityTypeExtensions.cs
@@ -411,7 +411,7 @@ public static bool RemoveCheckConstraint(
         ///     Returns all <see cref="ICheckConstraint" /> contained in the entity type.
         /// </summary>
         /// <param name="entityType"> The entity type to get the check constraints for. </param>
-        public static IReadOnlyList<ICheckConstraint> GetCheckConstraints([NotNull] this IEntityType entityType)
+        public static IEnumerable<ICheckConstraint> GetCheckConstraints([NotNull] this IEntityType entityType)
             => CheckConstraint.GetCheckConstraints(entityType);
     }
 }
diff --git a/src/EFCore.Relational/Metadata/Internal/CheckConstraint.cs b/src/EFCore.Relational/Metadata/Internal/CheckConstraint.cs
index face3b93b7a..63d2fce7615 100644
--- a/src/EFCore.Relational/Metadata/Internal/CheckConstraint.cs
+++ b/src/EFCore.Relational/Metadata/Internal/CheckConstraint.cs
@@ -19,6 +19,8 @@ namespace Microsoft.EntityFrameworkCore.Metadata.Internal
     /// </summary>
     public class CheckConstraint : IConventionCheckConstraint
     {
+        private ConfigurationSource _configurationSource;
+
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
         ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
@@ -38,7 +40,7 @@ public CheckConstraint(
             EntityType = entityType;
             Name = name;
             Sql = sql;
-            ConfigurationSource = configurationSource;
+            _configurationSource = configurationSource;
 
             var dataDictionary = GetAnnotationsDictionary(EntityType);
             if (dataDictionary == null)
@@ -63,11 +65,11 @@ public CheckConstraint(
         ///     any release. You should only use it directly in your code with extreme caution and knowing that
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
-        public static IReadOnlyList<CheckConstraint> GetCheckConstraints([NotNull] IEntityType entityType)
+        public static IEnumerable<CheckConstraint> GetCheckConstraints([NotNull] IEntityType entityType)
         {
             Check.NotNull(entityType, nameof(entityType));
 
-            return GetAnnotationsDictionary(entityType)?.Values.ToList() ?? new List<CheckConstraint>();
+            return GetAnnotationsDictionary(entityType)?.Values ?? Enumerable.Empty<CheckConstraint>();
         }
 
         /// <summary>
@@ -133,15 +135,7 @@ public static bool RemoveCheckConstraint(
         ///     any release. You should only use it directly in your code with extreme caution and knowing that
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
-        public virtual ConfigurationSource ConfigurationSource { get; private set; }
-
-        /// <summary>
-        ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
-        ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
-        ///     any release. You should only use it directly in your code with extreme caution and knowing that
-        ///     doing so can result in application failures when updating to a new Entity Framework Core release.
-        /// </summary>
-        public virtual ConfigurationSource GetConfigurationSource() => ConfigurationSource;
+        public virtual ConfigurationSource GetConfigurationSource() => _configurationSource;
 
         /// <summary>
         ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
@@ -150,8 +144,8 @@ public static bool RemoveCheckConstraint(
         ///     doing so can result in application failures when updating to a new Entity Framework Core release.
         /// </summary>
         public virtual void UpdateConfigurationSource(ConfigurationSource configurationSource)
-        { 
-            ConfigurationSource = configurationSource.Max(ConfigurationSource);
+        {
+            _configurationSource = configurationSource.Max(_configurationSource);
         }
 
         private static Dictionary<string, CheckConstraint> GetAnnotationsDictionary(IEntityType entityType)