Invoke Build Callbacks at Lifetime Scope Creation

src/Autofac/Autofac.csproj

@@ -59,6 +59,11 @@
   </ItemGroup>
 
   <ItemGroup>
+    <Compile Update="Builder\BuildCallbackServiceResources.Designer.cs">
+      <DesignTime>True</DesignTime>
+      <AutoGen>True</AutoGen>
+      <DependentUpon>BuildCallbackServiceResources.resx</DependentUpon>
+    </Compile>
     <Compile Update="Builder\RegistrationBuilderResources.Designer.cs">
       <DesignTime>True</DesignTime>
       <AutoGen>True</AutoGen>
@@ -267,6 +272,10 @@
   </ItemGroup>
 
   <ItemGroup>
+    <EmbeddedResource Update="Builder\BuildCallbackServiceResources.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>BuildCallbackServiceResources.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
     <EmbeddedResource Update="Builder\RegistrationBuilderResources.resx">
       <Generator>ResXFileCodeGenerator</Generator>
       <LastGenOutput>RegistrationBuilderResources.Designer.cs</LastGenOutput>

src/Autofac/Builder/BuildCallbackManager.cs

@@ -0,0 +1,63 @@
+// This software is part of the Autofac IoC container
+// Copyright © 2019 Autofac Contributors
+// https://autofac.org
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+
+using System.Linq;
+using Autofac.Core;
+
+namespace Autofac.Builder
+{
+    internal static class BuildCallbackManager
+    {
+        private static readonly TypedService CallbackServiceType = new TypedService(typeof(BuildCallbackService));
+
+        private const string BuildCallbacksExecutedKey = nameof(BuildCallbacksExecutedKey);
+
+        /// <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.RegistrationsFor(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 = scope.ResolveComponent(request) as BuildCallbackService;
+
+                srv.Metadata[BuildCallbacksExecutedKey] = true;
+
+                // Run the callbacks for the relevant scope.
+                component.Execute(scope);
+            }
+        }
+    }
+}

src/Autofac/Builder/BuildCallbackService.cs

@@ -0,0 +1,77 @@
+// This software is part of the Autofac IoC container
+// Copyright © 2019 Autofac Contributors
+// https://autofac.org
+//
+// Permission is hereby granted, free of charge, to any person
+// obtaining a copy of this software and associated documentation
+// files (the "Software"), to deal in the Software without
+// restriction, including without limitation the rights to use,
+// copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the
+// Software is furnished to do so, subject to the following
+// conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+// OTHER DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace Autofac.Builder
+{
+    /// <summary>
+    /// Represent a collection of callbacks that can be run after a container or scope is 'built'.
+    /// </summary>
+    internal class BuildCallbackService
+    {
+        private List<Action<ILifetimeScope>> Callbacks { get; set; } = new List<Action<ILifetimeScope>>();
+
+        private bool HasRun => Callbacks == null;
+
+        /// <summary>
+        /// Add a callback to the set that will get executed.
+        /// </summary>
+        /// <param name="callback">The callback to run.</param>
+        public void AddCallback(Action<ILifetimeScope> callback)
+        {
+            if (callback == null) throw new ArgumentNullException(nameof(callback));
+
+            Callbacks.Add(callback);
+        }
+
+        public void Execute(ILifetimeScope scope)
+        {
+            if (scope == null) throw new ArgumentNullException(nameof(scope));
+
+            if (HasRun)
+            {
+                throw new InvalidOperationException(BuildCallbackServiceResources.BuildCallbacksAlreadyRun);
+            }
+
+            try
+            {
+                foreach (var callback in Callbacks)
+                {
+                    callback(scope);
+                }
+            }
+            finally
+            {
+                // Clear the reference to the callbacks to release any held scopes (and function as a do-not-run flag)
+                // This object will be a singleton instance in the container/scope, so the initial function scopes that
+                // define the callbacks could be holding onto closure resources. We want the GC to take that back.
+                Callbacks = null;
+            }
+        }
+    }
+}

src/Autofac/Builder/BuildCallbackServiceResources.resx

@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+
+    Version 2.0
+
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+
+    Example:
+
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="BuildCallbacksAlreadyRun" xml:space="preserve">
+    <value>This set of build callbacks have already run.</value>
+  </data>
+</root>