Fix a race condition in ReconfigureTenant

src/Autofac.Multitenant/MultitenantContainer.cs

@@ -394,25 +394,43 @@ private ILifetimeScope CreateTenantScope(object tenantId, Action<ContainerBuilde
     /// <returns><c>true</c> if an existing configuration was removed; otherwise, <c>false</c>.</returns>
     /// <seealso cref="ConfigurationActionBuilder"/>
     /// <seealso cref="ConfigureTenant(object, Action{ContainerBuilder})"/>
+    [SuppressMessage("CA1513", "CA1513", Justification = "ObjectDisposedException.ThrowIf is not available in all target frameworks.")]
     public bool ReconfigureTenant(object tenantId, Action<ContainerBuilder> configuration)
     {
         if (configuration == null)
         {
             throw new ArgumentNullException(nameof(configuration));
         }
 
+        if (_isDisposed == 1)
+        {
+            throw new ObjectDisposedException(nameof(ApplicationContainer));
+        }
+
         tenantId ??= _defaultTenantId;
 
-        var removed = false;
-        if (_tenantLifetimeScopes.TryRemove(tenantId, out var tenantScope))
+        var lifetimeScope = ApplicationContainer.BeginLifetimeScope(TenantLifetimeScopeTag, configuration);
+
+        ILifetimeScope? disposedLifetimeScope = null;
+        _tenantLifetimeScopes.AddOrUpdate(
+            tenantId,
+            _ => lifetimeScope,
+            (_, updatedLifetimeScope) =>
+            {
+                // We defer the existing scope Dispose()
+                // as we prefer enabling the new scope as quickly
+                // as possible.
+                disposedLifetimeScope = updatedLifetimeScope;
+                return lifetimeScope;
+            });
+
+        if (disposedLifetimeScope == null)
         {
-            tenantScope.Dispose();
-            removed = true;
+            return false;
         }
 
-        CreateTenantScope(tenantId, configuration);
-
-        return removed;
+        disposedLifetimeScope.Dispose();
+        return true;
     }
 
     /// <summary>

test/Autofac.Multitenant.Test/MultitenantContainerFixture.cs

@@ -567,6 +567,52 @@ public void ReconfigureTenant_ReconfigureSingleton()
         Assert.IsType<StubDependency1Impl3>(mtc.Resolve<IStubDependency1>());
     }
 
+    [Fact]
+    public void ReconfigureTenant_RequiresConfiguration()
+    {
+        var builder = new ContainerBuilder();
+        var strategy = new StubTenantIdentificationStrategy()
+        {
+            TenantId = "tenant1",
+        };
+        using var mtc = new MultitenantContainer(strategy, builder.Build());
+        mtc.ConfigureTenant("tenant1", b => b.RegisterType<StubDependency1Impl2>().AsImplementedInterfaces().SingleInstance());
+
+        Assert.Throws<ArgumentNullException>(() => mtc.ReconfigureTenant("tenant1", null));
+    }
+
+    [Fact]
+    public void ReconfigureTenant_ThrowsAfterDisposal()
+    {
+        var builder = new ContainerBuilder();
+        var strategy = new StubTenantIdentificationStrategy()
+        {
+            TenantId = "tenant1",
+        };
+        using var mtc = new MultitenantContainer(strategy, builder.Build());
+        mtc.Dispose();
+        Assert.Throws<ObjectDisposedException>(() => mtc.ReconfigureTenant("tenant1", _ => { }));
+    }
+
+    [Fact]
+    public void ReconfigureTenant_AddLifetimeScope()
+    {
+        var builder = new ContainerBuilder();
+        var strategy = new StubTenantIdentificationStrategy()
+        {
+            TenantId = "tenant1",
+        };
+        using var mtc = new MultitenantContainer(strategy, builder.Build());
+        mtc.ConfigureTenant("tenant1", b => b.RegisterType<StubDependency1Impl2>().AsImplementedInterfaces().SingleInstance());
+
+        // Simulate another thread playing with the MTC
+        mtc.RemoveTenant("tenant1");
+
+        mtc.ReconfigureTenant("tenant1", b => b.RegisterType<StubDependency1Impl3>().AsImplementedInterfaces().SingleInstance());
+
+        Assert.IsType<StubDependency1Impl3>(mtc.Resolve<IStubDependency1>());
+    }
+
     [Fact]
     public void GetTenants_CheckRegistered()
     {