Add GetChangeToken to EndpointDataSource (#649)

src/Microsoft.AspNetCore.Routing/CompositeEndpointDataSource.cs

@@ -69,8 +69,8 @@ namespace Microsoft.AspNetCore.Routing
                     foreach (var dataSource in _dataSources)
                     {
                         Extensions.Primitives.ChangeToken.OnChange(
-                            () => dataSource.ChangeToken,
-                            () => HandleChange());
+                            dataSource.GetChangeToken,
+                            HandleChange);
                     }
                 }
             }

src/Microsoft.AspNetCore.Routing/DataSourceDependentCache.cs

@@ -47,7 +47,7 @@ namespace Microsoft.AspNetCore.Routing
         {
             lock (_lock)
             {
-                var changeToken = _dataSource.ChangeToken;
+                var changeToken = _dataSource.GetChangeToken();
                 _value = _initializeCore(_dataSource.Endpoints);
 
                 changeToken.RegisterChangeCallback(_initializerWithState, null);

src/Microsoft.AspNetCore.Routing/EndpointDataSource.cs

@@ -8,7 +8,15 @@ namespace Microsoft.AspNetCore.Routing
 {
     public abstract class EndpointDataSource
     {
-        public abstract IChangeToken ChangeToken { get; }
+        public virtual IChangeToken ChangeToken { get; }
+
+        // Plan is to replace ChangeToken property with GetChangeToken
+        // Temporarily have both to avoid breaking MVC
+        // https://github.com/aspnet/Routing/issues/634
+        public virtual IChangeToken GetChangeToken()
+        {
+            return ChangeToken;
+        }
 
         public abstract IReadOnlyList<Endpoint> Endpoints { get; }
     }

src/Microsoft.AspNetCore.Routing/RouteValuesBasedEndpointFinder.cs

@@ -32,8 +32,8 @@ namespace Microsoft.AspNetCore.Routing
 
             // Register for changes in endpoints
             Extensions.Primitives.ChangeToken.OnChange(
-                () => _endpointDataSource.ChangeToken,
-                () => HandleChange());
+                _endpointDataSource.GetChangeToken,
+                HandleChange);
         }
 
         public IEnumerable<Endpoint> FindEndpoints(RouteValuesBasedEndpointFinderContext context)
@@ -70,8 +70,8 @@ namespace Microsoft.AspNetCore.Routing
             // 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());
+                _endpointDataSource.GetChangeToken,
+                HandleChange);
         }
 
         private void BuildOutboundMatches()

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

@@ -114,7 +114,7 @@ namespace Microsoft.AspNetCore.Routing
             var endpoints = compositeDataSource.Endpoints;
 
             // Assert1
-            var changeToken1 = compositeDataSource.ChangeToken;
+            var changeToken1 = compositeDataSource.GetChangeToken();
             var token = Assert.IsType<CancellationChangeToken>(changeToken1);
             Assert.False(token.HasChanged); // initial state
 
@@ -126,7 +126,7 @@ namespace Microsoft.AspNetCore.Routing
 
             // Assert2
             Assert.True(changeToken1.HasChanged); // old token is expected to be changed
-            var changeToken2 = compositeDataSource.ChangeToken; // new token is in a unchanged state
+            var changeToken2 = compositeDataSource.GetChangeToken(); // new token is in a unchanged state
             Assert.NotSame(changeToken2, changeToken1);
             token = Assert.IsType<CancellationChangeToken>(changeToken2);
             Assert.False(token.HasChanged);
@@ -139,7 +139,7 @@ namespace Microsoft.AspNetCore.Routing
 
             // Assert2
             Assert.True(changeToken2.HasChanged); // old token is expected to be changed
-            var changeToken3 = compositeDataSource.ChangeToken; // new token is in a unchanged state
+            var changeToken3 = compositeDataSource.GetChangeToken(); // new token is in a unchanged state
             Assert.NotSame(changeToken3, changeToken2);
             Assert.NotSame(changeToken3, changeToken1);
             token = Assert.IsType<CancellationChangeToken>(changeToken3);