Kanject.Core.Channels.Annotations.Attributes 3.13.1

Kanject.Core.Channels.Annotations.Attributes

Attribute-only package for Kanject channels: [Channel], [ChannelProducer], and the ChannelMode, ChannelFullMode and ChannelLifetime enums. It contains marker types only — no implementation. The Kanject.Core.Channels.Annotations source generator reads these attributes and emits the channel wiring.

Installation

Most projects never reference this package directly: Kanject.Core.Channels depends on it, so the attributes are available as soon as the runtime is installed.

dotnet add package Kanject.Core.Channels.Annotations.Attributes

Reference it directly only when you want the attribute types without the runtime — for example in a shared contracts assembly that declares handlers compiled elsewhere.

Targets netstandard2.0, .NET 8, .NET 9 and .NET 10. The netstandard2.0 build exists so the Roslyn generator, which must itself target netstandard2.0, can load the same types.

Usage

using Kanject.Core.Channels.Annotations.Attributes;
using Kanject.Core.Channels.Annotations.Attributes.Enums;

public sealed partial class OrderProjector
{
    [Channel(
        Capacity = 5000,
        BatchSize = 25,
        FlushIntervalMs = 200,
        Mode = ChannelMode.InProcess,
        Lifetime = ChannelLifetime.Scoped)]
    public ValueTask ProjectAsync(ReadOnlyMemory<OrderPlaced> batch, CancellationToken ct)
    {
        // handle the batch
        return ValueTask.CompletedTask;
    }
}

To turn the attribute into code, add the Kanject.Core.Channels.Annotations generator to the project that declares the handler.

Attributes

[Channel] (methods)

Marks a method as a batched, async channel handler. The containing type must be partial.

[ChannelProducer] (classes, multiple allowed)

Declares a producer-only port for an item type: [ChannelProducer(typeof(OrderPlaced))], with an optional ChannelName. The type is part of the public surface, but no generator emits code for it yet. Kanject.Core.Channels.Annotations reports every use as error KANCHN017, so the attribute can't compile into a silent no-op. For a producer-only port today, declare a [Channel(Mode = ChannelMode.Distributed)] handler: it generates the writer interface and DI extension without a consumer.

Enums

Namespace Kanject.Core.Channels.Annotations.Attributes.Enums.

ChannelFullMode exists so this package does not need System.Threading.Channels. The generator maps each member to the BoundedChannelFullMode member of the same name (the two enums order their drop members differently, so the mapping is never numeric). A value outside the enum, such as (ChannelFullMode)42, is error KANCHN018. DropOldest removes the oldest buffered item to make room, DropNewest removes the newest buffered item, and DropWrite discards the item being written; all three lose data silently, which is why they raise warning KANCHN013.

Related packages

License

Licensed under the Kanject Code Libraries License Agreement (KCLLA); the full text ships in this package as LICENSE.md. Organizations whose trailing-twelve-month gross revenue and total funding raised are each below US$250,000 may use it at no cost under the Free Tier. At or above either threshold a commercial license is required — contact commercial@kanjectbusiness.com.