I'm currently working on a project using .NET 8 and Autofac for dependency injection. I've encountered a scenario where I need to check if an instance of Autofac.Core.Lifetime.LifetimeScope is already disposed to prevent accessing disposed objects, which leads to an ObjectDisposedException.

I came across the UnsafeAccessor as a potential solution to access private or internal members safely without reflection, but I'm not sure how to apply it in this context to check the IsDisposed property of LifetimeScope.

I try this

[UnsafeAccessor(UnsafeAccessorKind.Method, Name = "get_IsDisposed")]
private static extern ref bool GetIsDisposed(global::Autofac.Core.Lifetime.LifetimeScope @this);

but get exception

System.MissingMethodException: Method not found: 'Autofac.Core.Lifetime.LifetimeScope.get_IsDisposed'. 

I make a simple Demo

I want to get the IsDisposed property of Autofac.Core.Lifetime.LifetimeScope，to check if Autofac.Core.Lifetime.LifetimeScope is already disposed.

I'm currently working on a project using .NET 8 and Autofac for dependency injection. I've encountered a scenario where I need to check if an instance of Autofac.Core.Lifetime.LifetimeScope is already disposed to prevent accessing disposed objects, which leads to an ObjectDisposedException.

I came across the UnsafeAccessor as a potential solution to access private or internal members safely without reflection, but I'm not sure how to apply it in this context to check the IsDisposed property of LifetimeScope.

I try this

[UnsafeAccessor(UnsafeAccessorKind.Method, Name = "get_IsDisposed")]
private static extern ref bool GetIsDisposed(global::Autofac.Core.Lifetime.LifetimeScope @this);

but get exception

System.MissingMethodException: Method not found: 'Autofac.Core.Lifetime.LifetimeScope.get_IsDisposed'. 

I make a simple Demo

https://dotnetfiddle/79xX5J

I want to get the IsDisposed property of Autofac.Core.Lifetime.LifetimeScope，to check if Autofac.Core.Lifetime.LifetimeScope is already disposed.

• c#
• dependency-injection
• autofac
• -8.0

• I need to check if an instance of Autofac.Core.Lifetime.LifetimeScope is already disposed why? That smells of an application bug. Why would anything other than Autofac dispose of an object? Why does application code outside the scope try to access a scoped object? Don't perform the check and use the exception to find out what's wrong in the application code. If you need to use a scoped object in a singleton, use a factory method or an explicit scope to create the scoped object when needed – Panagiotis Kanavos Commented Nov 20, 2024 at 7:25
• Post the code that throws because it tries to access the disposed object. People can show you how to fix this. Covering up the error just means you'll get into deeper trouble – Panagiotis Kanavos Commented Nov 20, 2024 at 7:27

1 Answer 1

From purely technical point of view - IsDisposed is a property and is defined on Autofac.Util.Disposable (LifetimeScope inherits from it) so you need to remove the ref modifier (it is for fields) from the method declaration and use correct type:

[UnsafeAccessor(UnsafeAccessorKind.Method, Name = "get_IsDisposed")]
private static extern bool IsDisposed(Autofac.Util.Disposable c);

And usage:

var builder = new ContainerBuilder();
var container = builder.Build();

bool isDisposed = IsDisposed(container.BeginLifetimeScope() as Autofac.Util.Disposable);
// or
// IsDisposed(container.BeginLifetimeScope() as Autofac.Core.Lifetime.LifetimeScope);

Demo @dotnetfiddle

But in general you should avoid doing this, such approach can be brittle for multiple reasons like library authors deciding to change the internal implementation or maybe some concurrency stuff (for example scope being disposed after check but before method invocation).

Usually the correct way to handle such situations is to figure out why the scope is disposed before you want to use it and fix that (also I have a slight suspicion that you are doing some background work stuff and/or fire-and-fet but without seeing actual code this is just a guess, but if this is the case the way to handle it is to use some background processing with appropriate lifetime scopes).