Merge branch 'merge/release/2.2-to-master'

src/Microsoft.AspNetCore.Routing.Abstractions/LinkGenerator.cs

@@ -2,18 +2,21 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using Microsoft.AspNetCore.Http;
 
 namespace Microsoft.AspNetCore.Routing
 {
-    public interface ILinkGenerator
+    public abstract class LinkGenerator
     {
-        bool TryGetLink(
+        public abstract bool TryGetLink(
+            HttpContext httpContext,
             IEnumerable<Endpoint> endpoints,
             RouteValueDictionary explicitValues,
             RouteValueDictionary ambientValues,
             out string link);
 
-        string GetLink(
+        public abstract string GetLink(
+            HttpContext httpContext,
             IEnumerable<Endpoint> endpoints,
             RouteValueDictionary explicitValues,
             RouteValueDictionary ambientValues);

src/Microsoft.AspNetCore.Routing/CompositeEndpointDataSource.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.Routing
@@ -12,9 +13,9 @@ namespace Microsoft.AspNetCore.Routing
     {
         private readonly EndpointDataSource[] _dataSources;
         private readonly object _lock;
-
-        private IChangeToken _changeToken;
         private IReadOnlyList<Endpoint> _endpoints;
+        private IChangeToken _consumerChangeToken;
+        private CancellationTokenSource _cts;
 
         internal CompositeEndpointDataSource(IEnumerable<EndpointDataSource> dataSources)
         {
@@ -23,6 +24,7 @@ namespace Microsoft.AspNetCore.Routing
                 throw new ArgumentNullException(nameof(dataSources));
             }
 
+            CreateChangeToken();
             _dataSources = dataSources.ToArray();
             _lock = new object();
         }
@@ -32,7 +34,7 @@ namespace Microsoft.AspNetCore.Routing
             get
             {
                 EnsureInitialized();
-                return _changeToken;
+                return _consumerChangeToken;
             }
         }
 
@@ -48,7 +50,7 @@ namespace Microsoft.AspNetCore.Routing
         // Defer initialization to avoid doing lots of reflection on startup.
         private void EnsureInitialized()
         {
-            if (_changeToken == null)
+            if (_endpoints == null)
             {
                 Initialize();
             }
@@ -60,11 +62,49 @@ namespace Microsoft.AspNetCore.Routing
         {
             lock (_lock)
             {
-                _changeToken = new CompositeChangeToken(_dataSources.Select(d => d.ChangeToken).ToArray());
+                if (_endpoints == null)
+                {
+                    _endpoints = _dataSources.SelectMany(d => d.Endpoints).ToArray();
+
+                    foreach (var dataSource in _dataSources)
+                    {
+                        Extensions.Primitives.ChangeToken.OnChange(
+                            () => dataSource.ChangeToken,
+                            () => HandleChange());
+                    }
+                }
+            }
+        }
+
+        private void HandleChange()
+        {
+            lock (_lock)
+            {
+                // Refresh the endpoints from datasource so that callbacks can get the latest endpoints
                 _endpoints = _dataSources.SelectMany(d => d.Endpoints).ToArray();
 
-                _changeToken.RegisterChangeCallback((state) => Initialize(), null);
+                // Prevent consumers from re-registering callback to inflight events as that can 
+                // cause a stackoverflow
+                // Example:
+                // 1. B registers A
+                // 2. A fires event causing B's callback to get called
+                // 3. B executes some code in its callback, but needs to re-register callback 
+                //    in the same callback
+                var oldTokenSource = _cts;
+                var oldToken = _consumerChangeToken;
+
+                CreateChangeToken();
+
+                // Raise consumer callbacks. Any new callback registration would happen on the new token
+                // created in earlier step.
+                oldTokenSource.Cancel();
             }
         }
+
+        private void CreateChangeToken()
+        {
+            _cts = new CancellationTokenSource();
+            _consumerChangeToken = new CancellationChangeToken(_cts.Token);
+        }
     }
 }

src/Microsoft.AspNetCore.Routing/DefaultLinkGenerator.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text.Encodings.Web;
+using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Routing.Internal;
 using Microsoft.AspNetCore.Routing.Matchers;
 using Microsoft.AspNetCore.Routing.Template;
@@ -13,7 +14,7 @@ using Microsoft.Extensions.ObjectPool;
 
 namespace Microsoft.AspNetCore.Routing
 {
-    internal class DefaultLinkGenerator : ILinkGenerator
+    internal class DefaultLinkGenerator : LinkGenerator
     {
         private readonly MatchProcessorFactory _matchProcessorFactory;
         private readonly ObjectPool<UriBuildingContext> _uriBuildingContextPool;
@@ -29,12 +30,13 @@ namespace Microsoft.AspNetCore.Routing
             _logger = logger;
         }
 
-        public string GetLink(
+        public override string GetLink(
+            HttpContext httpContext,
             IEnumerable<Endpoint> endpoints,
             RouteValueDictionary explicitValues,
             RouteValueDictionary ambientValues)
         {
-            if (TryGetLink(endpoints, explicitValues, ambientValues, out var link))
+            if (TryGetLink(httpContext, endpoints, explicitValues, ambientValues, out var link))
             {
                 return link;
             }
@@ -42,7 +44,8 @@ namespace Microsoft.AspNetCore.Routing
             throw new InvalidOperationException("Could not find a matching endpoint to generate a link.");
         }
 
-        public bool TryGetLink(
+        public override bool TryGetLink(
+            HttpContext httpContext,
             IEnumerable<Endpoint> endpoints,
             RouteValueDictionary explicitValues,
             RouteValueDictionary ambientValues,
@@ -64,7 +67,7 @@ namespace Microsoft.AspNetCore.Routing
 
             foreach (var endpoint in matcherEndpoints)
             {
-                link = GetLink(endpoint, explicitValues, ambientValues);
+                link = GetLink(httpContext, endpoint, explicitValues, ambientValues);
                 if (link != null)
                 {
                     return true;
@@ -75,6 +78,7 @@ namespace Microsoft.AspNetCore.Routing
         }
 
         private string GetLink(
+            HttpContext httpContext,
             MatcherEndpoint endpoint,
             RouteValueDictionary explicitValues,
             RouteValueDictionary ambientValues)
@@ -92,7 +96,7 @@ namespace Microsoft.AspNetCore.Routing
                 return null;
             }
 
-            if (!Match(endpoint, templateValuesResult.CombinedValues))
+            if (!Match(httpContext, endpoint, templateValuesResult.CombinedValues))
             {
                 return null;
             }
@@ -100,7 +104,7 @@ namespace Microsoft.AspNetCore.Routing
             return templateBinder.BindValues(templateValuesResult.AcceptedValues);
         }
 
-        private bool Match(MatcherEndpoint endpoint, RouteValueDictionary routeValues)
+        private bool Match(HttpContext httpContext, MatcherEndpoint endpoint, RouteValueDictionary routeValues)
         {
             if (routeValues == null)
             {
@@ -117,7 +121,7 @@ namespace Microsoft.AspNetCore.Routing
                 }
 
                 var matchProcessor = _matchProcessorFactory.Create(matchProcessorReference);
-                if (!matchProcessor.ProcessOutbound(httpContext: null, routeValues))
+                if (!matchProcessor.ProcessOutbound(httpContext, routeValues))
                 {
                     return false;
                 }

src/Microsoft.AspNetCore.Routing/DependencyInjection/DispatcherServiceCollectionExtensions.cs

@@ -41,7 +41,7 @@ namespace Microsoft.Extensions.DependencyInjection
             // Link generation related services
             services.TryAddSingleton<IEndpointFinder<string>, NameBasedEndpointFinder>();
             services.TryAddSingleton<IEndpointFinder<RouteValuesBasedEndpointFinderContext>, RouteValuesBasedEndpointFinder>();
-            services.TryAddSingleton<ILinkGenerator, DefaultLinkGenerator>();
+            services.TryAddSingleton<LinkGenerator, DefaultLinkGenerator>();
             //
             // Endpoint Selection
             //

src/Microsoft.AspNetCore.Routing/RouteValuesBasedEndpointFinder.cs

@@ -27,7 +27,13 @@ namespace Microsoft.AspNetCore.Routing
             _endpointDataSource = endpointDataSource;
             _objectPool = objectPool;
 
+            // Build initial matches
             BuildOutboundMatches();
+
+            // Register for changes in endpoints
+            Extensions.Primitives.ChangeToken.OnChange(
+                () => _endpointDataSource.ChangeToken,
+                () => HandleChange());
         }
 
         public IEnumerable<Endpoint> FindEndpoints(RouteValuesBasedEndpointFinderContext context)
@@ -56,14 +62,28 @@ namespace Microsoft.AspNetCore.Routing
                 .Select(match => (MatcherEndpoint)match.Entry.Data);
         }
 
-        private void BuildOutboundMatches()
+        private void HandleChange()
         {
-            var (allOutboundMatches, namedOutboundMatches) = GetOutboundMatches();
+            // rebuild the matches
-            _namedMatches = GetNamedMatches(namedOutboundMatches);
+            BuildOutboundMatches();
-            _allMatchesLinkGenerationTree = new LinkGenerationDecisionTree(allOutboundMatches.ToArray());
+
+            // re-register the callback as the change token is one time use only and a new change token
+            // is produced every time
+            Extensions.Primitives.ChangeToken.OnChange(
+                () => _endpointDataSource.ChangeToken,
+                () => HandleChange());
         }
 
-        private (IEnumerable<OutboundMatch>, IDictionary<string, List<OutboundMatch>>) GetOutboundMatches()
+        private void BuildOutboundMatches()
+        {
+            // Refresh the matches in the case where a datasource's endpoints changes. The following is OK to do
+            // as refresh of new endpoints happens within a lock and also these fields are not publicly accessible.
+            var (allMatches, namedMatches) = GetOutboundMatches();
+            _namedMatches = GetNamedMatches(namedMatches);
+            _allMatchesLinkGenerationTree = new LinkGenerationDecisionTree(allMatches.ToArray());
+        }
+
+        protected virtual (IEnumerable<OutboundMatch>, IDictionary<string, List<OutboundMatch>>) GetOutboundMatches()
         {
             var allOutboundMatches = new List<OutboundMatch>();
             var namedOutboundMatches = new Dictionary<string, List<OutboundMatch>>(StringComparer.OrdinalIgnoreCase);

test/Microsoft.AspNetCore.Routing.Tests/CompositeEndpointDataSourceTest.cs

@@ -0,0 +1,183 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Routing.Matchers;
+using Microsoft.AspNetCore.Routing.TestObjects;
+using Microsoft.Extensions.Primitives;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Routing
+{
+    public class CompositeEndpointDataSourceTest
+    {
+        [Fact]
+        public void CreatesShallowCopyOf_ListOfEndpoints()
+        {
+            // Arrange
+            var endpoint1 = CreateEndpoint("/a");
+            var endpoint2 = CreateEndpoint("/b");
+            var dataSource = new DefaultEndpointDataSource(new Endpoint[] { endpoint1, endpoint2 });
+            var compositeDataSource = new CompositeEndpointDataSource(new[] { dataSource });
+
+            // Act
+            var endpoints = compositeDataSource.Endpoints;
+
+            // Assert
+            Assert.NotSame(endpoints, dataSource.Endpoints);
+            Assert.Equal(endpoints, dataSource.Endpoints);
+        }
+
+        [Fact]
+        public void Endpoints_ReturnsAllEndpoints_FromMultipleDataSources()
+        {
+            // Arrange
+            var endpoint1 = CreateEndpoint("/a");
+            var endpoint2 = CreateEndpoint("/b");
+            var endpoint3 = CreateEndpoint("/c");
+            var endpoint4 = CreateEndpoint("/d");
+            var endpoint5 = CreateEndpoint("/e");
+            var compositeDataSource = new CompositeEndpointDataSource(new[]
+            {
+                new DefaultEndpointDataSource(new Endpoint[] { endpoint1, endpoint2 }),
+                new DefaultEndpointDataSource(new Endpoint[] { endpoint3, endpoint4 }),
+                new DefaultEndpointDataSource(new Endpoint[] { endpoint5 }),
+            });
+
+            // Act
+            var endpoints = compositeDataSource.Endpoints;
+
+            // Assert
+            Assert.Collection(
+                endpoints,
+                (ep) => Assert.Same(endpoint1, ep),
+                (ep) => Assert.Same(endpoint2, ep),
+                (ep) => Assert.Same(endpoint3, ep),
+                (ep) => Assert.Same(endpoint4, ep),
+                (ep) => Assert.Same(endpoint5, ep));
+        }
+
+        [Fact]
+        public void DataSourceChanges_AreReflected_InEndpoints()
+        {
+            // Arrange1
+            var endpoint1 = CreateEndpoint("/a");
+            var dataSource1 = new DynamicEndpointDataSource(endpoint1);
+            var compositeDataSource = new CompositeEndpointDataSource(new[] { dataSource1 });
+
+            // Act1
+            var endpoints = compositeDataSource.Endpoints;
+
+            // Assert1
+            var endpoint = Assert.Single(endpoints);
+            Assert.Same(endpoint1, endpoint);
+
+            // Arrange2
+            var endpoint2 = CreateEndpoint("/b");
+
+            // Act2
+            dataSource1.AddEndpoint(endpoint2);
+
+            // Assert2
+            Assert.Collection(
+                compositeDataSource.Endpoints,
+                (ep) => Assert.Same(endpoint1, ep),
+                (ep) => Assert.Same(endpoint2, ep));
+
+            // Arrange3
+            var endpoint3 = CreateEndpoint("/c");
+
+            // Act2
+            dataSource1.AddEndpoint(endpoint3);
+
+            // Assert2
+            Assert.Collection(
+                compositeDataSource.Endpoints,
+                (ep) => Assert.Same(endpoint1, ep),
+                (ep) => Assert.Same(endpoint2, ep),
+                (ep) => Assert.Same(endpoint3, ep));
+        }
+
+        [Fact]
+        public void ConsumerChangeToken_IsRefreshed_WhenDataSourceCallbackFires()
+        {
+            // Arrange1
+            var endpoint1 = CreateEndpoint("/a");
+            var dataSource1 = new DynamicEndpointDataSource(endpoint1);
+            var compositeDataSource = new CompositeEndpointDataSource(new[] { dataSource1 });
+
+            // Act1
+            var endpoints = compositeDataSource.Endpoints;
+
+            // Assert1
+            var changeToken1 = compositeDataSource.ChangeToken;
+            var token = Assert.IsType<CancellationChangeToken>(changeToken1);
+            Assert.False(token.HasChanged); // initial state
+
+            // Arrange2
+            var endpoint2 = CreateEndpoint("/b");
+
+            // Act2
+            dataSource1.AddEndpoint(endpoint2);
+
+            // Assert2
+            Assert.True(changeToken1.HasChanged); // old token is expected to be changed
+            var changeToken2 = compositeDataSource.ChangeToken; // new token is in a unchanged state
+            Assert.NotSame(changeToken2, changeToken1);
+            token = Assert.IsType<CancellationChangeToken>(changeToken2);
+            Assert.False(token.HasChanged);
+
+            // Arrange3
+            var endpoint3 = CreateEndpoint("/c");
+
+            // Act2
+            dataSource1.AddEndpoint(endpoint3);
+
+            // Assert2
+            Assert.True(changeToken2.HasChanged); // old token is expected to be changed
+            var changeToken3 = compositeDataSource.ChangeToken; // new token is in a unchanged state
+            Assert.NotSame(changeToken3, changeToken2);
+            Assert.NotSame(changeToken3, changeToken1);
+            token = Assert.IsType<CancellationChangeToken>(changeToken3);
+            Assert.False(token.HasChanged);
+        }
+
+        private MatcherEndpoint CreateEndpoint(
+            string template,
+            object defaultValues = null,
+            object requiredValues = null,
+            int order = 0,
+            string routeName = null)
+        {
+            var defaults = defaultValues == null ? new RouteValueDictionary() : new RouteValueDictionary(defaultValues);
+            var required = requiredValues == null ? new RouteValueDictionary() : new RouteValueDictionary(requiredValues);
+
+            return new MatcherEndpoint(
+                next => (httpContext) => Task.CompletedTask,
+                template,
+                defaults,
+                required,
+                order,
+                EndpointMetadataCollection.Empty,
+                null);
+        }
+
+        private class CustomEndpointDataSource : EndpointDataSource
+        {
+            private readonly CancellationTokenSource _cts;
+            private readonly CancellationChangeToken _token;
+
+            public CustomEndpointDataSource()
+            {
+                _cts = new CancellationTokenSource();
+                _token = new CancellationChangeToken(_cts.Token);
+            }
+
+            public override IChangeToken ChangeToken => _token;
+            public override IReadOnlyList<Endpoint> Endpoints => Array.Empty<Endpoint>();
+        }
+    }
+}

test/Microsoft.AspNetCore.Routing.Tests/DefaultLinkGeneratorTest.cs

@@ -7,7 +7,6 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Routing.EndpointFinders;
 using Microsoft.AspNetCore.Routing.Internal;
 using Microsoft.AspNetCore.Routing.Matchers;
-using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.ObjectPool;
 using Microsoft.Extensions.Options;
@@ -27,7 +26,11 @@ namespace Microsoft.AspNetCore.Routing
             var context = CreateRouteValuesContext(new { controller = "Home" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home", link);
@@ -44,7 +47,11 @@ namespace Microsoft.AspNetCore.Routing
 
             // Act & Assert
             var exception = Assert.Throws<InvalidOperationException>(
-                () => linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues));
+                () => linkGenerator.GetLink(
+                    httpContext: null,
+                    new[] { endpoint },
+                    context.ExplicitValues,
+                    context.AmbientValues));
             Assert.Equal(expectedMessage, exception.Message);
         }
 
@@ -58,6 +65,7 @@ namespace Microsoft.AspNetCore.Routing
 
             // Act
             var canGenerateLink = linkGenerator.TryGetLink(
+                httpContext: null,
                 new[] { endpoint },
                 context.ExplicitValues,
                 context.AmbientValues,
@@ -80,6 +88,7 @@ namespace Microsoft.AspNetCore.Routing
 
             // Act
             var link = linkGenerator.GetLink(
+                httpContext: null,
                 new[] { endpoint1, endpoint2, endpoint3 },
                 context.ExplicitValues,
                 context.AmbientValues);
@@ -100,6 +109,7 @@ namespace Microsoft.AspNetCore.Routing
 
             // Act
             var link = linkGenerator.GetLink(
+                httpContext: null,
                 new[] { endpoint1, endpoint2, endpoint3 },
                 context.ExplicitValues,
                 context.AmbientValues);
@@ -119,7 +129,11 @@ namespace Microsoft.AspNetCore.Routing
                 ambientValues: new { controller = "Home", action = "Index" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index?name=name%20with%20%25special%20%23characters", link);
@@ -136,7 +150,11 @@ namespace Microsoft.AspNetCore.Routing
                 new { controller = "Home", action = "Index" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index?color=red&color=green&color=blue", link);
@@ -153,7 +171,11 @@ namespace Microsoft.AspNetCore.Routing
                 new { controller = "Home", action = "Index" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index?items=10&items=20&items=30", link);
@@ -170,7 +192,11 @@ namespace Microsoft.AspNetCore.Routing
                 new { controller = "Home", action = "Index" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index", link);
@@ -187,7 +213,11 @@ namespace Microsoft.AspNetCore.Routing
                 new { controller = "Home", action = "Index" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index?page=1&color=red&color=green&color=blue&message=textfortest", link);
@@ -204,7 +234,11 @@ namespace Microsoft.AspNetCore.Routing
                 ambientValues: new { controller = "Home" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index", link);
@@ -582,7 +616,11 @@ namespace Microsoft.AspNetCore.Routing
                 suppliedValues: new { action = "Index", controller = "Home", name = "products" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index/products", link);
@@ -598,7 +636,11 @@ namespace Microsoft.AspNetCore.Routing
                 suppliedValues: new { action = "Index", controller = "Home" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index", link);
@@ -616,7 +658,11 @@ namespace Microsoft.AspNetCore.Routing
                 suppliedValues: new { action = "Index", controller = "Home", name = "products" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index/products", link);
@@ -634,7 +680,11 @@ namespace Microsoft.AspNetCore.Routing
                 suppliedValues: new { action = "Index", controller = "Home" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index", link);
@@ -650,7 +700,11 @@ namespace Microsoft.AspNetCore.Routing
                 suppliedValues: new { action = "Index", controller = "Home", name = "products", format = "json" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index/products?format=json", link);
@@ -710,7 +764,11 @@ namespace Microsoft.AspNetCore.Routing
                 suppliedValues: new { action = "Index", controller = "Home" });
 
             // Act
-            var link = linkGenerator.GetLink(new[] { endpoint }, context.ExplicitValues, context.AmbientValues);
+            var link = linkGenerator.GetLink(
+                httpContext: null,
+                new[] { endpoint },
+                context.ExplicitValues,
+                context.AmbientValues);
 
             // Assert
             Assert.Equal("/Home/Index", link);
@@ -796,7 +854,7 @@ namespace Microsoft.AspNetCore.Routing
                 null);
         }
 
-        private ILinkGenerator CreateLinkGenerator()
+        private LinkGenerator CreateLinkGenerator()
         {
             return new DefaultLinkGenerator(
                 new DefaultMatchProcessorFactory(

test/Microsoft.AspNetCore.Routing.Tests/RouteValueBasedEndpointFinderTest.cs

@@ -0,0 +1,256 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Routing.Internal;
+using Microsoft.AspNetCore.Routing.Matchers;
+using Microsoft.AspNetCore.Routing.TestObjects;
+using Microsoft.AspNetCore.Routing.Tree;
+using Microsoft.Extensions.ObjectPool;
+using Microsoft.Extensions.Options;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Routing
+{
+    public class RouteValueBasedEndpointFinderTest
+    {
+        [Fact]
+        public void GetOutboundMatches_GetsNamedMatchesFor_EndpointsHaving_IRouteNameMetadata()
+        {
+            // Arrange
+            var endpoint1 = CreateEndpoint("/a");
+            var endpoint2 = CreateEndpoint("/a", routeName: "named");
+
+            // Act
+            var finder = CreateEndpointFinder(endpoint1, endpoint2);
+
+            // Assert
+            Assert.NotNull(finder.AllMatches);
+            Assert.Equal(2, finder.AllMatches.Count());
+            Assert.NotNull(finder.NamedMatches);
+            Assert.True(finder.NamedMatches.TryGetValue("named", out var namedMatches));
+            var namedMatch = Assert.Single(namedMatches);
+            var actual = Assert.IsType<MatcherEndpoint>(namedMatch.Entry.Data);
+            Assert.Same(endpoint2, actual);
+        }
+
+        [Fact]
+        public void GetOutboundMatches_GroupsMultipleEndpoints_WithSameName()
+        {
+            // Arrange
+            var endpoint1 = CreateEndpoint("/a");
+            var endpoint2 = CreateEndpoint("/a", routeName: "named");
+            var endpoint3 = CreateEndpoint("/b", routeName: "named");
+
+            // Act
+            var finder = CreateEndpointFinder(endpoint1, endpoint2, endpoint3);
+
+            // Assert
+            Assert.NotNull(finder.AllMatches);
+            Assert.Equal(3, finder.AllMatches.Count());
+            Assert.NotNull(finder.NamedMatches);
+            Assert.True(finder.NamedMatches.TryGetValue("named", out var namedMatches));
+            Assert.Equal(2, namedMatches.Count);
+            Assert.Same(endpoint2, Assert.IsType<MatcherEndpoint>(namedMatches[0].Entry.Data));
+            Assert.Same(endpoint3, Assert.IsType<MatcherEndpoint>(namedMatches[1].Entry.Data));
+        }
+
+        [Fact]
+        public void GetOutboundMatches_GroupsMultipleEndpoints_WithSameName_IgnoringCase()
+        {
+            // Arrange
+            var endpoint1 = CreateEndpoint("/a");
+            var endpoint2 = CreateEndpoint("/a", routeName: "named");
+            var endpoint3 = CreateEndpoint("/b", routeName: "NaMed");
+
+            // Act
+            var finder = CreateEndpointFinder(endpoint1, endpoint2, endpoint3);
+
+            // Assert
+            Assert.NotNull(finder.AllMatches);
+            Assert.Equal(3, finder.AllMatches.Count());
+            Assert.NotNull(finder.NamedMatches);
+            Assert.True(finder.NamedMatches.TryGetValue("named", out var namedMatches));
+            Assert.Equal(2, namedMatches.Count);
+            Assert.Same(endpoint2, Assert.IsType<MatcherEndpoint>(namedMatches[0].Entry.Data));
+            Assert.Same(endpoint3, Assert.IsType<MatcherEndpoint>(namedMatches[1].Entry.Data));
+        }
+
+        [Fact]
+        public void GetOutboundMatches_DoesNotGetNamedMatchesFor_EndpointsHaving_INameMetadata()
+        {
+            // Arrange
+            var endpoint1 = CreateEndpoint("/a");
+            var endpoint2 = CreateEndpoint("/a", routeName: "named");
+            var endpoint3 = CreateEndpoint(
+                "/b",
+                metadataCollection: new EndpointMetadataCollection(new[] { new NameMetadata("named") }));
+
+            // Act
+            var finder = CreateEndpointFinder(endpoint1, endpoint2);
+
+            // Assert
+            Assert.NotNull(finder.AllMatches);
+            Assert.Equal(2, finder.AllMatches.Count());
+            Assert.NotNull(finder.NamedMatches);
+            Assert.True(finder.NamedMatches.TryGetValue("named", out var namedMatches));
+            var namedMatch = Assert.Single(namedMatches);
+            var actual = Assert.IsType<MatcherEndpoint>(namedMatch.Entry.Data);
+            Assert.Same(endpoint2, actual);
+        }
+
+        [Fact]
+        public void EndpointDataSource_ChangeCallback_Refreshes_OutboundMatches()
+        {
+            // Arrange 1
+            var endpoint1 = CreateEndpoint("/a");
+            var dynamicDataSource = new DynamicEndpointDataSource(new[] { endpoint1 });
+            var objectPoolProvider = new DefaultObjectPoolProvider();
+            var objectPool = objectPoolProvider.Create(new UriBuilderContextPooledObjectPolicy());
+
+            // Act 1
+            var finder = new CustomRouteValuesBasedEndpointFinder(
+                new CompositeEndpointDataSource(new[] { dynamicDataSource }),
+                objectPool);
+
+            // Assert 1
+            Assert.NotNull(finder.AllMatches);
+            var match = Assert.Single(finder.AllMatches);
+            var actual = Assert.IsType<MatcherEndpoint>(match.Entry.Data);
+            Assert.Same(endpoint1, actual);
+
+            // Arrange 2
+            var endpoint2 = CreateEndpoint("/b");
+
+            // Act 2
+            // Trigger change
+            dynamicDataSource.AddEndpoint(endpoint2);
+
+            // Arrange 2
+            var endpoint3 = CreateEndpoint("/c");
+
+            // Act 2
+            // Trigger change
+            dynamicDataSource.AddEndpoint(endpoint3);
+
+            // Arrange 3
+            var endpoint4 = CreateEndpoint("/d");
+
+            // Act 3
+            // Trigger change
+            dynamicDataSource.AddEndpoint(endpoint4);
+
+            // Assert 3
+            Assert.NotNull(finder.AllMatches);
+            Assert.Collection(
+                finder.AllMatches,
+                (m) =>
+                {
+                    actual = Assert.IsType<MatcherEndpoint>(m.Entry.Data);
+                    Assert.Same(endpoint1, actual);
+                },
+                (m) =>
+                {
+                    actual = Assert.IsType<MatcherEndpoint>(m.Entry.Data);
+                    Assert.Same(endpoint2, actual);
+                },
+                (m) =>
+                {
+                    actual = Assert.IsType<MatcherEndpoint>(m.Entry.Data);
+                    Assert.Same(endpoint3, actual);
+                },
+                (m) =>
+                {
+                    actual = Assert.IsType<MatcherEndpoint>(m.Entry.Data);
+                    Assert.Same(endpoint4, actual);
+                });
+        }
+
+        private CustomRouteValuesBasedEndpointFinder CreateEndpointFinder(params Endpoint[] endpoints)
+        {
+            return CreateEndpointFinder(new DefaultEndpointDataSource(endpoints));
+        }
+
+        private CustomRouteValuesBasedEndpointFinder CreateEndpointFinder(params EndpointDataSource[] endpointDataSources)
+        {
+            var objectPoolProvider = new DefaultObjectPoolProvider();
+            var objectPool = objectPoolProvider.Create(new UriBuilderContextPooledObjectPolicy());
+
+            return new CustomRouteValuesBasedEndpointFinder(
+                new CompositeEndpointDataSource(endpointDataSources),
+                objectPool);
+        }
+
+        private MatcherEndpoint CreateEndpoint(
+            string template,
+            object defaultValues = null,
+            object requiredValues = null,
+            int order = 0,
+            string routeName = null,
+            EndpointMetadataCollection metadataCollection = null)
+        {
+            var defaults = defaultValues == null ? new RouteValueDictionary() : new RouteValueDictionary(defaultValues);
+            var required = requiredValues == null ? new RouteValueDictionary() : new RouteValueDictionary(requiredValues);
+
+            if (metadataCollection == null)
+            {
+                metadataCollection = EndpointMetadataCollection.Empty;
+                if (!string.IsNullOrEmpty(routeName))
+                {
+                    metadataCollection = new EndpointMetadataCollection(new[] { new RouteNameMetadata(routeName) });
+                }
+            }
+
+            return new MatcherEndpoint(
+                next => (httpContext) => Task.CompletedTask,
+                template,
+                defaults,
+                required,
+                order,
+                metadataCollection,
+                null);
+        }
+
+        private class RouteNameMetadata : IRouteNameMetadata
+        {
+            public RouteNameMetadata(string name)
+            {
+                Name = name;
+            }
+            public string Name { get; }
+        }
+
+        private class NameMetadata : INameMetadata
+        {
+            public NameMetadata(string name)
+            {
+                Name = name;
+            }
+            public string Name { get; }
+        }
+
+        private class CustomRouteValuesBasedEndpointFinder : RouteValuesBasedEndpointFinder
+        {
+            public CustomRouteValuesBasedEndpointFinder(
+                CompositeEndpointDataSource endpointDataSource,
+                ObjectPool<UriBuildingContext> objectPool)
+                : base(endpointDataSource, objectPool)
+            {
+            }
+
+            public IEnumerable<OutboundMatch> AllMatches { get; private set; }
+
+            public IDictionary<string, List<OutboundMatch>> NamedMatches { get; private set; }
+
+            protected override (IEnumerable<OutboundMatch>, IDictionary<string, List<OutboundMatch>>) GetOutboundMatches()
+            {
+                var matches = base.GetOutboundMatches();
+                AllMatches = matches.Item1;
+                NamedMatches = matches.Item2;
+                return matches;
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.Routing.Tests/TestObjects/DynamicEndpointDataSource.cs

@@ -0,0 +1,53 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.Threading;
+using Microsoft.Extensions.Primitives;
+
+namespace Microsoft.AspNetCore.Routing.TestObjects
+{
+    public class DynamicEndpointDataSource : EndpointDataSource
+    {
+        private readonly List<Endpoint> _endpoints;
+        private CancellationTokenSource _cts;
+        private CancellationChangeToken _changeToken;
+        private readonly object _lock;
+
+        public DynamicEndpointDataSource(params Endpoint[] endpoints)
+        {
+            _endpoints = new List<Endpoint>();
+            _endpoints.AddRange(endpoints);
+            _lock = new object();
+
+            CreateChangeToken();
+        }
+
+        public override IChangeToken ChangeToken => _changeToken;
+
+        public override IReadOnlyList<Endpoint> Endpoints => _endpoints;
+
+        // Trigger change
+        public void AddEndpoint(Endpoint endpoint)
+        {
+            _endpoints.Add(endpoint);
+
+            // Capture the old tokens so that we can raise the callbacks on them. This is important so that
+            // consumers do not register callbacks on an inflight event causing a stackoverflow.
+            var oldTokenSource = _cts;
+            var oldToken = _changeToken;
+
+            CreateChangeToken();
+
+            // Raise consumer callbacks. Any new callback registration would happen on the new token
+            // created in earlier step.
+            oldTokenSource.Cancel();
+        }
+
+        private void CreateChangeToken()
+        {
+            _cts = new CancellationTokenSource();
+            _changeToken = new CancellationChangeToken(_cts.Token);
+        }
+    }
+}