Merge pull request #136 from TimeWarpEngineering/Cramer-2019-05-15

Implement IDisposable on BaseComponent

Author: StevenTCramer

Documentation/TemplateOverview.md

@@ -1,23 +1,25 @@
-## TimeWarp-Blazor Template
+# TimeWarp-Blazor Template
 
-### Installation
+## Installation
 
-```
+```console
 dotnet new --install TimeWarp.AspNetCore.Blazor.Templates
 ```
 
-### Usage
+## Usage
 
-```
+```console
 dotnet new timewarp-blazor -n MyBlazorApp
 ```
 
-### Projects
-MyBlazorApp.Client<br/>
-MyBlazorApp.Server<br/>
+## Projects
+
+MyBlazorApp.Client  
+MyBlazorApp.Server  
 MyBlazorApp.Shared
 
-### Test Projects
-MyBlazorApp.Client.Integration.Tests<br/>
-MyBlazorApp.Server.Integration.Tests<br/>
+## Test Projects
+
+MyBlazorApp.Client.Integration.Tests  
+MyBlazorApp.Server.Integration.Tests  
 MyBlazorApp.EndToEnd.Tests

source/BlazorState/Components/BlazorStateComponent.cs

@@ -10,7 +10,7 @@
   /// And exposes StateHasChanged
   /// </summary>
   /// <remarks>Implements IBlazorStateComponent by Injecting</remarks>
-  public class BlazorStateComponent : ComponentBase,
+  public class BlazorStateComponent : ComponentBase, IDisposable,
      IBlazorStateComponent
   {
     static readonly ConcurrentDictionary<string, int> s_InstanceCounts = new ConcurrentDictionary<string, int>();
@@ -59,5 +59,7 @@ protected T GetState<T>()
       Subscriptions.Add(stateType, this);
       return Store.GetState<T>();
     }
+
+    public void Dispose() => Subscriptions.Remove(this);
   }
 }

source/BlazorState/Subscriptions.cs

@@ -2,18 +2,41 @@
 {
   using System;
   using System.Collections.Generic;
+  using System.Linq;
   using Microsoft.Extensions.Logging;
 
   public class Subscriptions
   {
+    private readonly struct Subscription : IEquatable<Subscription>
+    {
+      public Subscription(Type aStateType, string aComponentId, WeakReference<BlazorStateComponent> aBlazorStateComponentReference)
+      {
+        StateType = aStateType;
+        ComponentId = aComponentId;
+        BlazorStateComponentReference = aBlazorStateComponentReference;
+      }
+
+      public Type StateType { get; }
+      public string ComponentId { get; }
+      public WeakReference<BlazorStateComponent> BlazorStateComponentReference { get; }
+
+      public bool Equals(Subscription aSubscription) =>
+        EqualityComparer<Type>.Default.Equals(StateType, aSubscription.StateType) &&
+        ComponentId == aSubscription.ComponentId &&
+        EqualityComparer<WeakReference<BlazorStateComponent>>.Default.Equals(BlazorStateComponentReference, aSubscription.BlazorStateComponentReference);
+
+      public static bool operator ==(Subscription aLeftSubscription, Subscription aRightSubscription) => aLeftSubscription.Equals(aRightSubscription);
+      public static bool operator !=(Subscription aLeftSubscription, Subscription aRightSubscription) => !(aLeftSubscription == aRightSubscription);
+    }
+
     public Subscriptions(ILogger<Subscriptions> aLogger)
     {
       Logger = aLogger;
-      BlazorStateComponentReferencesDictionary = new Dictionary<Type, List<WeakReference<BlazorStateComponent>>>();
+      BlazorStateComponentReferencesList = new List<Subscription>();
     }
 
     private ILogger Logger { get; }
-    private Dictionary<Type, List<WeakReference<BlazorStateComponent>>> BlazorStateComponentReferencesDictionary { get; }
+    private List<Subscription> BlazorStateComponentReferencesList { get; }
 
     public Subscriptions Add<T>(BlazorStateComponent aBlazorStateComponent)
     {
@@ -23,18 +46,27 @@ public Subscriptions Add<T>(BlazorStateComponent aBlazorStateComponent)
     }
     public Subscriptions Add(Type aType, BlazorStateComponent aBlazorStateComponent)
     {
-
-      if (!(BlazorStateComponentReferencesDictionary.TryGetValue(aType, out List<WeakReference<BlazorStateComponent>> blazorStateComponentReferences)))
+      // Add only once.
+      if (!BlazorStateComponentReferencesList.Any(aSubscription => aSubscription.StateType == aType && aSubscription.ComponentId == aBlazorStateComponent.Id))
       {
-        blazorStateComponentReferences = new List<WeakReference<BlazorStateComponent>>();
-        BlazorStateComponentReferencesDictionary.Add(aType, blazorStateComponentReferences);
-      }
+        var subscription = new Subscription(
+          aType,
+          aBlazorStateComponent.Id,
+          new WeakReference<BlazorStateComponent>(aBlazorStateComponent));
 
-      blazorStateComponentReferences.Add(new WeakReference<BlazorStateComponent>(aBlazorStateComponent));
+        BlazorStateComponentReferencesList.Add(subscription);
+      }
 
       return this;
     }
 
+    public Subscriptions Remove(BlazorStateComponent aBlazorStateComponent)
+    {
+      Logger.LogDebug($"Removing Subscription for {aBlazorStateComponent.Id}");
+      BlazorStateComponentReferencesList.RemoveAll(aRecord => aRecord.ComponentId == aBlazorStateComponent.Id);
+
+      return this;
+    }
     /// <summary>
     /// Will iterate over all subscriptions for the given type and call ReRender on each.
     /// If the target component no longer exists it will remove its subscription.
@@ -54,27 +86,31 @@ public void ReRenderSubscribers<T>()
     /// <param name="aType"></param>
     public void ReRenderSubscribers(Type aType)
     {
-      //GC.Collect();  // I added the collect to test that I am not holding strong references and they were collected.
-      bool isAny = BlazorStateComponentReferencesDictionary.TryGetValue(aType, out List<WeakReference<BlazorStateComponent>> blazorStateblazorStateComponentReferencesComponents);
-      if (isAny)
+      IEnumerable<Subscription> subscriptions = BlazorStateComponentReferencesList.Where(aRecord => aRecord.StateType == aType);
+      foreach (Subscription subscription in subscriptions)
       {
-        Logger.LogDebug($"ReRendering {blazorStateblazorStateComponentReferencesComponents.Count} Subscribers for state of type: {aType.Name}");
-        WeakReference<BlazorStateComponent>[] blazorStateComponentReferencesArray = blazorStateblazorStateComponentReferencesComponents.ToArray();
-
-        foreach (WeakReference<BlazorStateComponent> aBlazorStateComponentReference in blazorStateComponentReferencesArray)
+        if (subscription.BlazorStateComponentReference.TryGetTarget(out BlazorStateComponent target))
         {
-          if (aBlazorStateComponentReference.TryGetTarget(out BlazorStateComponent target))
-          {
-            Logger.LogDebug($"ReRender: {target.GetType().Name}");
-            target.ReRender();
-          }
-          else
-          {
-            Logger.LogDebug($"Removing subscription to previously destroyed component.");
-            blazorStateblazorStateComponentReferencesComponents.Remove(aBlazorStateComponentReference);
-          }
+          Logger.LogDebug($"ReRender: {target.GetType().Name}");
+          target.ReRender();
+        }
+        else
+        {
+          // If Dispose is called will I ever have items in this list that got Garbage collected?
+          // Maybe for those that don't inherit from our BaseComponent.
+          BlazorStateComponentReferencesList.Remove(subscription);
         }
       }
     }
+
+    public override bool Equals(object obj) => obj is Subscriptions subscriptions && EqualityComparer<ILogger>.Default.Equals(Logger, subscriptions.Logger) && EqualityComparer<List<Subscription>>.Default.Equals(BlazorStateComponentReferencesList, subscriptions.BlazorStateComponentReferencesList);
+
+    public override int GetHashCode()
+    {
+      var hashCode = -914156548;
+      hashCode = hashCode * -1521134295 + EqualityComparer<ILogger>.Default.GetHashCode(Logger);
+      hashCode = hashCode * -1521134295 + EqualityComparer<List<Subscription>>.Default.GetHashCode(BlazorStateComponentReferencesList);
+      return hashCode;
+    }
   }
 }