use FrozenDictionary to store channels

Directory.Packages.props

@@ -17,6 +17,7 @@
     <PackageVersion Include="OpenTelemetry.Exporter.InMemory" Version="$(OtelVersion)" />
     <PackageVersion Include="OpenTelemetry.Exporter.Console" Version="$(OtelVersion)" />
     <PackageVersion Include="OpenTelemetry.Extensions.Hosting" Version="$(OtelVersion)" />
+    <PackageVersion Include="System.Collections.Immutable" Version="$(MExVersion)" />
     <PackageVersion Include="System.Diagnostics.DiagnosticSource" Version="8.0.1" />
     <PackageVersion Include="System.Threading.Channels" Version="8.0.0" />
     <PackageVersion Include="System.Threading.Tasks.Extensions" Version="[4.5.4,)" />

src/DCA.Extensions.BackgroundTask/BackgroundTaskDispatcher.cs

@@ -1,4 +1,4 @@
-using System.Collections.ObjectModel;
+using System.Collections.Frozen;
 using System.Diagnostics;
 using Microsoft.Extensions.Logging;
 
@@ -31,14 +31,11 @@ ValueTask DispatchAsync<TContext>(
 }
 
 public sealed class BackgroundTaskDispatcher(
-    ReadOnlyCollection<BackgroundTaskChannel> channels,
+    FrozenDictionary<string, BackgroundTaskChannel> channels,
     ILogger<BackgroundTaskDispatcher> logger,
     IServiceProvider serviceProvider)
     : IBackgroundTaskDispatcher
 {
-    private readonly ReadOnlyDictionary<string, BackgroundTaskChannel> _channels
-        = new(channels.ToDictionary(x => x.Key, x => x));
-
     public IServiceProvider ServiceProvider { get; } = serviceProvider;
 
     public ValueTask DispatchAsync<TContext>(
@@ -56,6 +53,6 @@ public ValueTask DispatchAsync<TContext>(
         );
 
         channel ??= Constants.DefaultChannelKey;
-        return _channels[channel].DispatchAsync(task, startNow);
+        return channels[channel].DispatchAsync(task, startNow);
     }
 }

src/DCA.Extensions.BackgroundTask/BackgroundTaskHostedService.cs

@@ -1,31 +1,31 @@
-using System.Collections.ObjectModel;
+using System.Collections.Frozen;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 
 namespace DCA.Extensions.BackgroundTask;
 
-/// <summary>
-/// A hosted service to manage task channels' lifetime
-/// </summary>
-/// <param name="logger"></param>
+/// <summary>
+/// A hosted service to manage task channels' lifetime
+/// </summary>
+/// <param name="logger"></param>
 /// <param name="channels"></param>
 public class BackgroundTaskHostedService(
     ILogger<BackgroundTaskHostedService> logger,
-    ReadOnlyCollection<BackgroundTaskChannel> channels) : IHostedService
+    FrozenDictionary<string, BackgroundTaskChannel> channels) : IHostedService
 {
     private readonly ILogger _logger = logger;
 
     public async Task StartAsync(CancellationToken cancellationToken)
     {
         _logger.LogInformation("Starting channels...");
-        await Task.WhenAll(channels.Select(x => x.StartAsync()));
+        await Task.WhenAll(channels.Values.Select(x => x.StartAsync()));
         _logger.LogInformation("Started channels...");
     }
 
     public async Task StopAsync(CancellationToken cancellationToken)
     {
         _logger.LogInformation("Stopping background channels...");
-        await Task.WhenAny(channels.Select(x => x.StopAsync()));
+        await Task.WhenAny(channels.Values.Select(x => x.StopAsync()));
         _logger.LogInformation("Stopped background channels...");
     }
 }

src/DCA.Extensions.BackgroundTask/BackgroundTaskServiceCollectionExtensions.cs

@@ -1,4 +1,4 @@
-using System.Collections.ObjectModel;
+using System.Collections.Frozen;
 using DCA.Extensions.BackgroundTask;
 using Microsoft.Extensions.Options;
 
@@ -34,8 +34,7 @@ public static IServiceCollection AddBackgroundTask(
             var options = sp.GetRequiredService<IOptions<BackgroundTaskOptions>>().Value;
             return options.Channels
                 .Select(opt => ActivatorUtilities.CreateInstance<BackgroundTaskChannel>(sp, opt))
-                .ToList()
-                .AsReadOnly();
+                .ToFrozenDictionary(x => x.Key, x => x);
         });
         services.AddSingleton<IBackgroundTaskDispatcher, BackgroundTaskDispatcher>();
         services.AddHostedService<BackgroundTaskHostedService>();

src/DCA.Extensions.BackgroundTask/DCA.Extensions.BackgroundTask.csproj

@@ -4,7 +4,7 @@
     <PackageReadmeFile>readme.md</PackageReadmeFile>
   </PropertyGroup>
   <ItemGroup>
-      <None Include="readme.md" Pack="true" PackagePath="\"/>
+      <None Include="readme.md" Pack="true" PackagePath="\" />
   </ItemGroup>
 
   <ItemGroup>
@@ -16,6 +16,7 @@
     <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" />
     <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" />
     <PackageReference Include="Microsoft.Extensions.Options" />
+    <PackageReference Include="System.Collections.Immutable" />
     <PackageReference Include="System.Diagnostics.DiagnosticSource" />
     <PackageReference Include="System.Threading.Channels" />
     <PackageReference Include="System.Threading.Tasks.Extensions" />

test/DCA.Extensions.BackgroundTask.Test/ProcessTests.cs

@@ -1,4 +1,4 @@
-using System.Collections.ObjectModel;
+using System.Collections.Frozen;
 using FluentAssertions;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
@@ -15,8 +15,8 @@ public async Task Should_RecordCheckpoints()
         services.AddBackgroundTask();
         var provider = services.BuildServiceProvider();
 
-        var channels = provider.GetRequiredService<ReadOnlyCollection<BackgroundTaskChannel>>();
-        var defaultChannel = channels.Single(ch => ch.Key == Constants.DefaultChannelKey);
+        var channels = provider.GetRequiredService<FrozenDictionary<string, BackgroundTaskChannel>>();
+        var defaultChannel = channels[Constants.DefaultChannelKey];
         var host = (BackgroundTaskHostedService)provider.GetRequiredService<IHostedService>();
         await host.StartAsync(default);