Remove IReceiveHotReloadContext and HotReloadContext (#31281)

* Remove IReceiveHotReloadContext and HotReloadContext

React to API review feedback. Substitute IReceiveHotReloadContext and HotReloadContext
with RenderHandle.IsHotReloading

* Fixup

* Update src/Components/Components/src/RenderHandle.cs

* Update src/Components/Components/src/Properties/ILLink.Substitutions.xml

* Update src/Components/Components/src/Properties/ILLink.Substitutions.xml

Author: pranavkm

src/Components/Components/src/ComponentBase.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.Components.HotReload;
 using Microsoft.AspNetCore.Components.Rendering;
 
 namespace Microsoft.AspNetCore.Components
@@ -22,15 +21,14 @@ namespace Microsoft.AspNetCore.Components
     /// Optional base class for components. Alternatively, components may
     /// implement <see cref="IComponent"/> directly.
     /// </summary>
-    public abstract class ComponentBase : IComponent, IHandleEvent, IHandleAfterRender, IReceiveHotReloadContext
+    public abstract class ComponentBase : IComponent, IHandleEvent, IHandleAfterRender
     {
         private readonly RenderFragment _renderFragment;
         private RenderHandle _renderHandle;
         private bool _initialized;
         private bool _hasNeverRendered = true;
         private bool _hasPendingQueuedRender;
         private bool _hasCalledOnAfterRender;
-        private HotReloadContext? _hotReloadContext;
 
         /// <summary>
         /// Constructs an instance of <see cref="ComponentBase"/>.
@@ -104,7 +102,7 @@ protected void StateHasChanged()
                 return;
             }
 
-            if (_hasNeverRendered || ShouldRender() || (_hotReloadContext?.IsHotReloading ?? false))
+            if (_hasNeverRendered || ShouldRender() || _renderHandle.IsHotReloading)
             {
                 _hasPendingQueuedRender = true;
 
@@ -331,10 +329,5 @@ Task IHandleAfterRender.OnAfterRenderAsync()
             // have to use "async void" and do their own exception handling in
             // the case where they want to start an async task.
         }
-
-        void IReceiveHotReloadContext.Receive(HotReloadContext context)
-        {
-            _hotReloadContext = context;
-        }
     }
 }

src/Components/Components/src/HotReload/HotReloadContext.cs

@@ -2,18 +2,16 @@
   <assembly fullname="Microsoft.AspNetCore.Components" >
     <!-- HotReload will not be available in a trimmed app. We'll attempt to aggressively remove all references to it. -->
     <type fullname="Microsoft.AspNetCore.Components.RenderTree.Renderer">
+      <!-- Renderer.IsHotReloading will always return false in a trimmed app. -->
+      <method signature="System.Boolean get_IsHotReloading()" body="stub" value="false" />
       <method signature="System.Void RenderRootComponentsOnHotReload()" body="remove" />
       <method signature="System.Void InitializeHotReload(System.IServiceProvider)" body="stub" />
-      <method signature="System.Void InstatiateComponentForHotReload(Microsoft.AspNetCore.Components.IComponent)" body="stub" />
       <method signature="System.Void CaptureRootComponentForHotReload(Microsoft.AspNetCore.Components.ParameterView,Microsoft.AspNetCore.Components.Rendering.ComponentState)" body="stub" />
       <method signature="System.Void DisposeForHotReload()" body="stub" />
     </type>
-    <type fullname="Microsoft.AspNetCore.Components.HotReload.HotReloadContext">
-      <method signature="System.Boolean get_IsHotReloading()" body="stub" value="false" />
-      <method signature="System.Void set_IsHotReloading(System.Boolean)" body="remove" />
-    </type>
-    <type fullname="Microsoft.AspNetCore.Components.RenderTree.RenderTreeDiffBuilder">
-      <method signature="System.Boolean IsHotReloading(Microsoft.AspNetCore.Components.RenderTree.Renderer)" body="stub" value="false" />
+    <!-- Avoid any overhead in RenderHandle.IsHotReloading by aggressively trimming it -->
+    <type fullname="Microsoft.AspNetCore.Components.RenderHandle">
+       <method signature="System.Boolean get_IsHotReloading()" body="stub" value="false" />
     </type>
   </assembly>
 </linker>

src/Components/Components/src/HotReload/IReceiveHotReloadContext.cs

@@ -8,11 +8,6 @@ Microsoft.AspNetCore.Components.ComponentApplicationState.PersistAsJson<TValue>(
 Microsoft.AspNetCore.Components.ComponentApplicationState.PersistState(string! key, byte[]! value) -> void
 Microsoft.AspNetCore.Components.ComponentApplicationState.TryTakeAsJson<TValue>(string! key, out TValue? instance) -> bool
 Microsoft.AspNetCore.Components.ComponentApplicationState.TryTakePersistedState(string! key, out byte[]? value) -> bool
-Microsoft.AspNetCore.Components.HotReload.HotReloadContext
-Microsoft.AspNetCore.Components.HotReload.HotReloadContext.HotReloadContext() -> void
-Microsoft.AspNetCore.Components.HotReload.HotReloadContext.IsHotReloading.get -> bool
-Microsoft.AspNetCore.Components.HotReload.IReceiveHotReloadContext
-Microsoft.AspNetCore.Components.HotReload.IReceiveHotReloadContext.Receive(Microsoft.AspNetCore.Components.HotReload.HotReloadContext! context) -> void
 Microsoft.AspNetCore.Components.Lifetime.ComponentApplicationLifetime
 Microsoft.AspNetCore.Components.Lifetime.ComponentApplicationLifetime.ComponentApplicationLifetime(Microsoft.Extensions.Logging.ILogger<Microsoft.AspNetCore.Components.Lifetime.ComponentApplicationLifetime!>! logger) -> void
 Microsoft.AspNetCore.Components.Lifetime.ComponentApplicationLifetime.PersistStateAsync(Microsoft.AspNetCore.Components.Lifetime.IComponentApplicationStateStore! store, Microsoft.AspNetCore.Components.RenderTree.Renderer! renderer) -> System.Threading.Tasks.Task!
@@ -21,6 +16,7 @@ Microsoft.AspNetCore.Components.Lifetime.ComponentApplicationLifetime.State.get
 Microsoft.AspNetCore.Components.Lifetime.IComponentApplicationStateStore
 Microsoft.AspNetCore.Components.Lifetime.IComponentApplicationStateStore.GetPersistedStateAsync() -> System.Threading.Tasks.Task<System.Collections.Generic.IDictionary<string!, byte[]!>!>!
 Microsoft.AspNetCore.Components.Lifetime.IComponentApplicationStateStore.PersistStateAsync(System.Collections.Generic.IReadOnlyDictionary<string!, byte[]!>! state) -> System.Threading.Tasks.Task!
+Microsoft.AspNetCore.Components.RenderHandle.IsHotReloading.get -> bool
 Microsoft.AspNetCore.Components.Rendering.RenderTreeBuilder.Dispose() -> void
 Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.get -> bool
 Microsoft.AspNetCore.Components.Routing.Router.PreferExactMatches.set -> void

src/Components/Components/src/Properties/ILLink.Substitutions.xml

@@ -12,7 +12,7 @@ namespace Microsoft.AspNetCore.Components
     /// </summary>
     public readonly struct RenderHandle
     {
-        private readonly Renderer _renderer;
+        private readonly Renderer? _renderer;
         private readonly int _componentId;
 
         internal RenderHandle(Renderer renderer, int componentId)
@@ -22,7 +22,7 @@ internal RenderHandle(Renderer renderer, int componentId)
         }
 
         /// <summary>
-        /// Gets the <see cref="Microsoft.AspNetCore.Components.Dispatcher" /> associated with the component.
+        /// Gets the <see cref="Components.Dispatcher" /> associated with the component.
         /// </summary>
         public Dispatcher Dispatcher
         {
@@ -41,8 +41,12 @@ public Dispatcher Dispatcher
         /// Gets a value that indicates whether the <see cref="RenderHandle"/> has been
         /// initialized and is ready to use.
         /// </summary>
-        public bool IsInitialized
-            => _renderer != null;
+        public bool IsInitialized => _renderer is not null;
+
+        /// <summary>
+        /// Gets a value that determines if the <see cref="Renderer"/> is triggering a render in response to a hot-reload change.
+        /// </summary>
+        public bool IsHotReloading => _renderer?.IsHotReloading ?? false;
 
         /// <summary>
         /// Notifies the renderer that the component should be rendered.

src/Components/Components/src/PublicAPI.Unshipped.txt

@@ -541,17 +541,12 @@ private static void UpdateRetainedChildComponent(
             var oldParameters = new ParameterView(ParameterViewLifetime.Unbound, oldTree, oldComponentIndex);
             var newParametersLifetime = new ParameterViewLifetime(diffContext.BatchBuilder);
             var newParameters = new ParameterView(newParametersLifetime, newTree, newComponentIndex);
-            if (!newParameters.DefinitelyEquals(oldParameters) || IsHotReloading(diffContext.Renderer))
+            if (!newParameters.DefinitelyEquals(oldParameters) || diffContext.Renderer.IsHotReloading)
             {
                 componentState.SetDirectParameters(newParameters);
             }
         }
 
-        /// <remarks>
-        /// Intentionally authored as a separate method so we can trim this code.
-        /// </remarks>
-        private static bool IsHotReloading(Renderer renderer) => renderer.HotReloadContext.IsHotReloading;
-
         private static int NextSiblingIndex(in RenderTreeFrame frame, int frameIndex)
         {
             switch (frame.FrameTypeField)

src/Components/Components/src/RenderHandle.cs

@@ -33,7 +33,6 @@ public abstract partial class Renderer : IDisposable, IAsyncDisposable
         private readonly Dictionary<ulong, ulong> _eventHandlerIdReplacements = new Dictionary<ulong, ulong>();
         private readonly ILogger<Renderer> _logger;
         private readonly ComponentFactory _componentFactory;
-        private HotReloadContext _hotReloadContext;
         private HotReloadEnvironment? _hotReloadEnvironment;
         private List<(ComponentState, ParameterView)>? _rootComponents;
 
@@ -102,8 +101,6 @@ public Renderer(IServiceProvider serviceProvider, ILoggerFactory loggerFactory,
 
         private void InitializeHotReload(IServiceProvider serviceProvider)
         {
-            _hotReloadContext = new();
-
             // HotReloadEnvironment is a test-specific feature and may not be available in a running app. We'll fallback to the default instance
             // if the test fixture does not provide one.
             _hotReloadEnvironment = serviceProvider.GetService<HotReloadEnvironment>() ?? HotReloadEnvironment.Instance;
@@ -131,7 +128,10 @@ private static IComponentActivator GetComponentActivatorOrDefault(IServiceProvid
         /// </summary>
         protected internal ElementReferenceContext? ElementReferenceContext { get; protected set; }
 
-        internal HotReloadContext HotReloadContext => _hotReloadContext;
+        /// <summary>
+        /// Gets a value that determines if the <see cref="Renderer"/> is triggering a render in response to a hot-reload change.
+        /// </summary>
+        internal bool IsHotReloading { get; private set; }
 
         private async void RenderRootComponentsOnHotReload()
         {
@@ -142,7 +142,7 @@ await Dispatcher.InvokeAsync(() =>
                     return;
                 }
 
-                HotReloadContext.IsHotReloading = true;
+                IsHotReloading = true;
                 try
                 {
                     foreach (var (componentState, initialParameters) in _rootComponents)
@@ -152,7 +152,7 @@ await Dispatcher.InvokeAsync(() =>
                 }
                 finally
                 {
-                    HotReloadContext.IsHotReloading = false;
+                    IsHotReloading = false;
                 }
             });
         }
@@ -164,20 +164,7 @@ await Dispatcher.InvokeAsync(() =>
         /// <returns>The component instance.</returns>
         protected IComponent InstantiateComponent([DynamicallyAccessedMembers(Component)] Type componentType)
         {
-            var component = _componentFactory.InstantiateComponent(_serviceProvider, componentType);
-            InstatiateComponentForHotReload(component);
-            return component;
-        }
-
-        /// <remarks>
-        /// Intentionally authored as a separate method call so we can trim this code.
-        /// </remarks>
-        private void InstatiateComponentForHotReload(IComponent component)
-        {
-            if (_hotReloadEnvironment is not null && _hotReloadEnvironment.IsHotReloadEnabled && component is IReceiveHotReloadContext receiveHotReloadContext)
-            {
-                receiveHotReloadContext.Receive(HotReloadContext);
-            }
+            return _componentFactory.InstantiateComponent(_serviceProvider, componentType);
         }
 
         /// <summary>