Improve DependencyInjection.AutoActivationExtensions

[geeknoid]

• Avoid calling MakeGenericType when possible.

• Delete the now-useless Hosting.StartupINitialization component.

Microsoft Reviewers: Open in CodeFlow

[martintmk]

@geeknoid, just wondering.

What is the replacement for IStartupInitialization?

[geeknoid]

@martintmk @ericstj What's the actual initialization API that was added to dotnet/runtime?

[geeknoid]

Ah, I think this is it: dotnet/runtime#87335

[geeknoid]

@steveharter Note that I'll add support for keyed services in a follow-on PR. I've got it all coded, but I need to wait for dotnet/runtime#89447 to be fixed, otherwise none of it works.

[ericstj]

Ah, I think this is it: dotnet/runtime#87335

Yes - the decision was made to not create a new initializer concept but instead incorporate the ask into hosted services themselves.

[RussKie]

@geeknoid @ericstj so how do we fix these?
https://github.com/Azure/dotnet-extensions-experimental/blob/0be630b7abb70e9316fcd7868aa64e088a9bbcfe/src/Microsoft.Azure.Extensions.DocumentDb.Cosmos/Extensions/DatabaseBuilder.cs#L199-L200
https://github.com/Azure/dotnet-extensions-experimental/blob/0be630b7abb70e9316fcd7868aa64e088a9bbcfe/src/Microsoft.Azure.Extensions.DocumentDb.Cosmos/Extensions/TableConfigurer.cs#L44-L45

[ericstj]

@steveharter can help with these - I believe you just need an IHostedLifecycleService implementation instead of delegate. You might even be able to use an existing IHostedService in the same library to do the job if one exists.

[steveharter]

Yes IHostedLifecycleService.Starting should be used since that occurs before IHostedService.Start.

Here's a pattern from an earlier prototype of mine that has a fallback in case the host doesn't support the new interface:

  internal sealed class StartupActivator : IHostedLifecycleService
  {
      private bool _done;

      Task IHostedLifecycleService.StartingAsync(CancellationToken cancellationToken) => Activate();

      // For backwards compat with hosts that don't support IHostedLifecycleService, use StartAsync().
      Task IHostedService.StartAsync(CancellationToken cancellationToken) => Activate();

      Task IHostedLifecycleService.StartedAsync(CancellationToken cancellationToken) => Task.CompletedTask;
      Task IHostedService.StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
      Task IHostedLifecycleService.StoppedAsync(CancellationToken cancellationToken) => Task.CompletedTask;
      Task IHostedLifecycleService.StoppingAsync(CancellationToken cancellationToken) => Task.CompletedTask;

      private Task Activate()
      {
          if (!_done)
          {
              // activate the service(s) here
              _done = true;
          }

          return Task.CompletedTask;
      }
}