/// <summary>
/// Initializes a new instance of the <see cref="PoolGetActivator{TLimit}"/> class.
/// </summary>
/// <param name="poolService">The service used to access the pool.</param>
/// <param name="registrationPolicy">The registration policy for the pool.</param>
public PoolGetActivator(PoolService poolService, IPooledRegistrationPolicy <TLimit> registrationPolicy)
{
_poolService = poolService;
_registrationPolicy = registrationPolicy;
}
private static void RegisterPooled <TLimit, TActivatorData, TSingleRegistrationStyle>(
IRegistrationBuilder <TLimit, TActivatorData, TSingleRegistrationStyle> registration,
IPooledRegistrationPolicy <TLimit> registrationPolicy,
object[]?tags)
where TSingleRegistrationStyle : SingleRegistrationStyle
where TActivatorData : IConcreteActivatorData
where TLimit : class
{
if (registration == null)
{
throw new ArgumentNullException(nameof(registration));
}
// Mark the lifetime appropriately.
var regData = registration.RegistrationData;
regData.Lifetime = new PooledLifetime();
regData.Sharing = InstanceSharing.None;
var callback = regData.DeferredCallback;
if (callback is null)
{
throw new NotSupportedException(RegistrationExtensionsResources.RequiresCallbackContainer);
}
if (registration.ActivatorData.Activator is ProvidedInstanceActivator)
{
// Can't use provided instance activators with pooling (because it would try to repeatedly activate).
throw new NotSupportedException(RegistrationExtensionsResources.CannotUseProvidedInstances);
}
var original = callback.Callback;
Action <IComponentRegistryBuilder> newCallback = registry =>
{
// Only do the additional registrations if we are still using a PooledLifetime.
if (!(regData.Lifetime is PooledLifetime))
{
original(registry);
return;
}
var pooledInstanceService = new UniqueService();
var instanceActivator = registration.ActivatorData.Activator;
if (registration.ResolvePipeline.Middleware.Any(c => c is CoreEventMiddleware ev && ev.EventType == ResolveEventType.OnRelease))
{
// OnRelease shouldn't be used with pooled instances, because if a policy chooses not to return them to the pool,
// the Disposal will be fired, not the OnRelease call; this means that OnRelease wouldn't fire until the container is disposed,
// which is not what we want.
throw new NotSupportedException(RegistrationExtensionsResources.OnReleaseNotSupported);
}
// First, we going to create a pooled instance activator, that will be resolved when we want to
// **actually** resolve a new instance (during 'Create').
// The instances themselves are owned by the pool, and will be disposed when the pool disposes
// (or when the instance is not returned to the pool).
var pooledInstanceRegistration = new ComponentRegistration(
Guid.NewGuid(),
instanceActivator,
RootScopeLifetime.Instance,
InstanceSharing.None,
InstanceOwnership.ExternallyOwned,
registration.ResolvePipeline,
new[] { pooledInstanceService },
new Dictionary <string, object?>());
registry.Register(pooledInstanceRegistration);
var poolService = new PoolService(pooledInstanceRegistration);
var poolRegistration = new ComponentRegistration(
Guid.NewGuid(),
new PoolActivator <TLimit>(pooledInstanceService, registrationPolicy),
RootScopeLifetime.Instance,
InstanceSharing.Shared,
InstanceOwnership.OwnedByLifetimeScope,
new[] { poolService },
new Dictionary <string, object?>());
registry.Register(poolRegistration);
var pooledGetLifetime = tags is null ? CurrentScopeLifetime.Instance : new MatchingScopeLifetime(tags);
// Next, create a new registration with a custom activator, that copies metadata and services from
// the original registration. This registration will access the pool and return an instance from it.
var poolGetRegistration = new ComponentRegistration(
Guid.NewGuid(),
new PoolGetActivator <TLimit>(poolService, registrationPolicy),
pooledGetLifetime,
InstanceSharing.Shared,
InstanceOwnership.OwnedByLifetimeScope,
regData.Services,
regData.Metadata);
registry.Register(poolGetRegistration);
// Finally, add a service pipeline stage to just before the sharing middleware, for each supported service, to extract the pooled instance from the pool instance container.
foreach (var srv in regData.Services)
{
registry.RegisterServiceMiddleware(srv, new PooledInstanceUnpackMiddleware <TLimit>(), MiddlewareInsertionMode.StartOfPhase);
}
};
callback.Callback = newCallback;
}