BuildCallbackManager.cs

// Copyright (c) Autofac Project. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.

using Autofac.Core;

namespace Autofac.Builder;

/// <summary>
/// Provides support for accessing/invoking the set of build callbacks, invoked on scope/container build.
/// </summary>
internal static class BuildCallbackManager
{
    private const string BuildCallbacksExecutedKey = nameof(BuildCallbacksExecutedKey);

    private static readonly TypedService CallbackServiceType = new(typeof(BuildCallbackService));

    /// <summary>
    /// Executes the newly-registered build callbacks for a given scope/container..
    /// </summary>
    /// <param name="scope">The new scope/container.</param>
    internal static void RunBuildCallbacks(ILifetimeScope scope)
    {
        var buildCallbackServices = scope.ComponentRegistry.ServiceRegistrationsFor(CallbackServiceType);

        foreach (var srv in buildCallbackServices)
        {
            // Use the metadata to track whether we've executed already, to avoid issuing a resolve request.
            if (srv.Metadata.ContainsKey(BuildCallbacksExecutedKey))
            {
                continue;
            }

            var request = new ResolveRequest(CallbackServiceType, srv, Enumerable.Empty<Parameter>());
            var component = (BuildCallbackService)scope.ResolveComponent(request);
            srv.Registration.Metadata[BuildCallbacksExecutedKey] = true;

            // Run the callbacks for the relevant scope.
            component.Execute(scope);
        }
    }
}