Does transient instances support disposing?

[jinyus]

Correct me if I'm wrong... I don't think this is supported but this snippet in your docs implies that it is.

final builder = IocContainerBuilder()
    ..add((container) => DatabaseConnection('my-connection-string'))
    ..add<UserRepository>(
      (container) => UserRepository(container<DatabaseConnection>()),
      dispose: (userRepository) => userRepository.dispose(),
    )

Based on the dispose extension, only scoped singletons are disposed. Therefore the dispose function in the above example will never be called.

ioc_container/lib/ioc_container.dart

Lines 221 to 234 in 313e32d

	Future<void> dispose() async {
	assert(isScoped, 'Only dispose scoped containers');
	for (final type in singletons.keys) {
	//Note: we don't need to check if the service is a singleton because
	//singleton service definitions never have dispose
	final serviceDefinition = serviceDefinitionsByType[type]!;
	//We can't do a null check here because if a Dart issue
	serviceDefinition._dispose.call(singletons[type]);
	await serviceDefinition._disposeAsync(singletons[type]);
	}
	singletons.clear();
	}

[MelbourneDeveloper]

Hi @jinyus

Good point!

I will fix the code example. Thanks for pointing it out

A PR to fix the doco would be welcome

[jinyus]

I was looking through the code while creating the PR and realized that there is nothing wrong with the docs because the services are treated as singletons when scoped; so the dispose method will be called.

There is a conundrum though, because factory singletons cannot have a dispose method:

ioc_container/lib/ioc_container.dart

Lines 24 to 27 in 313e32d

	}) : assert(
	!isSingleton || dispose == null,
	'Singleton factories cannot have a dispose method',
	),

So there is a memory leak where singletons created in a scope will never be disposed of. Let me know if you're ok with allowing singletons to have a dispose method and I will submit the PR.

[MelbourneDeveloper]

Sorry, yes, stored services do need dispose.

It's not a memory leak. That's by design. If you create a scope with disposable services, you need to dispose of them when you're finished.

[jinyus]

re: memory leak
I mean that factory singletons are never disposed in a scope because you cannot supply a dispose method when registering them. My PR fixes this.

eg:

final builder = IocContainerBuilder()
    ..addSingletonService(AuthenticationService())

final container = builder.toContainer();

final scope = container.scoped();

final authService = scope<AuthenticationService>();
print(authService.login('user', 'password'));

await scope.dispose(); // AuthenticationService is not disposed here

[MelbourneDeveloper]

You can You supply the dispose methods when you create the original container Get Outlook for Android<https://aka.ms/AAb9ysg>

…

________________________________ From: jinyus ***@***.***> Sent: Sunday, January 7, 2024 12:11:04 PM To: MelbourneDeveloper/ioc_container ***@***.***> Cc: Christian Findlay ***@***.***>; Comment ***@***.***> Subject: Re: [MelbourneDeveloper/ioc_container] Does transient instances support disposing? (Issue #14) re: memory leak I mean that factory singletons are never disposed in a scope because you cannot supply a dispose method when registering them. My PR fixes this. — Reply to this email directly, view it on GitHub<#14 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AD7MRS4SO3GM3PJFYKWRKRTYNHY2RAVCNFSM6AAAAABBPQRHDSVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNZZHEYDENZVGQ>. You are receiving this because you commented.Message ID: ***@***.***>

[jinyus]

Here is the code for addSingletonService:

ioc_container/lib/ioc_container.dart

Lines 153 to 158 in 313e32d

	void addSingletonService<T>(T service) => addServiceDefinition(
	ServiceDefinition<T>(
	(container) => service,
	isSingleton: true,
	),
	);

It doesn't allow you to supply a dispose method. So my code above would result in a memleak. Unless I'm mistaken.

[MelbourneDeveloper]

You can see here that the scoped method copies the whole service definition, which includes the dispose method

[jinyus]

Yes, but currently there is no way to supply a dispose method for Singletons, only transients allow it.

eg:

  ///Add a singleton service to the container.
  void addSingletonService<T>(T service) => addServiceDefinition(
        ServiceDefinition<T>(
          (container) => service,
          isSingleton: true,
        ),
      );

  ///1️⃣ Add a singleton factory to the container. The container
  ///will only call this once throughout the lifespan of the container
  void addSingleton<T>(
    T Function(
      IocContainer container,
    ) factory,
  ) =>
      addServiceDefinition<T>(
        ServiceDefinition<T>(
          (container) => factory(container),
          isSingleton: true,
        ),
      );

addSingleton and addSingletonService doesn't allow you to supply a dispose method.

[MelbourneDeveloper]

@jinyus ah yes! I see your point. I've have a look at this and see if there are any issues

Thanks 🙏🏼