3.0.0

What's Changed

Breaking Changes

• IEventHandler<T> methods now take parameter IRetryPolicy instead of RetryPolicy

before:

public interface IEventHandler<TEvent>
{
    Task Handle(TEvent @event, RetryPolicy retryPolicy, CancellationToken cancellationToken);
    Task OnError(Exception exception, TEvent @event, RetryPolicy retryPolicy, CancellationToken cancellationToken);
}

after:

public interface IEventHandler<TEvent>
{
    Task Handle(TEvent @event, IRetryPolicy retryPolicy, CancellationToken cancellationToken);
    Task OnError(Exception exception, TEvent @event, IRetryPolicy retryPolicy, CancellationToken cancellationToken);
}

Commits

• fix typo (7bf0892 by @petar-m)
• Introduce interface IRetryPolicy for RetryPolicy (895632d by @petar-m)

2.0.0

What's Changed

Breaking Changes

• IEventHandler<T> methods take additional parameter RetryPolicy

before:

public interface IEventHandler<TEvent>
{
    Task Handle(TEvent @event, CancellationToken cancellationToken);
    Task OnError(Exception exception, TEvent @event, CancellationToken cancellationToken);
}

after:

public interface IEventHandler<TEvent>
{
    Task Handle(TEvent @event, RetryPolicy retryPolicy, CancellationToken cancellationToken);
    Task OnError(Exception exception, TEvent @event, RetryPolicy retryPolicy, CancellationToken cancellationToken);
}

• EventHandlerRegistryBuilder registration methods renamed to omit 'Keyed' word

before:

services.AddEventHandlers(
            x => x.AddKeyedTransient<Event1, EventHandler1>()
                  .AddKeyedScoped<Event2, EventHandler2>()
                  .AddKeyedSingleton<Event3, EventHandler3>())

after:

services.AddEventHandlers(
            x => x.AddTransient<Event1, EventHandler1>()
                  .AddScoped<Event2, EventHandler2>()
                  .AddSingleton<Event3, EventHandler3>())

New Features

Retries

Retrying within event hadler can become a bottleneck. Imagine EventBroker is restricted to one concurrent handler. An exception is caught in Handle and retry is attempted after given time interval. Since Handle is not completed, there is no available "slot" to run other handlers while Handle is waiting.

Another option will be to use IEventBroker.PublishDeferred. This will eliminate the bottleneck but will itroduce different problems. The same event will be handled again by all handlers, meaning specaial care should be taken to make all handlers idempotent. Any additional information (e.g. number of retries) needs to be known, it should be carried with the event, introducing accidential complexity.

To avoid these problems, both IEventBroker Handle and OnError methods have RetryPolicy parameter.

RetryPolicy.RetryAfter() will schedule a retry only for the handler it is called from, without blocking. After the given time interval an instance of the handler will be resolved from the DI container (from a new scope) and executed with the same event instance.

RetryPolicy.Attempt is the current retry attempt for a given handler and event.
RetryPolicy.LastDelay is the time interval before the retry.

RetryPolicy.RetryRequested is used to coordinate retry request between Handle and OnError. RetryPolicy is passed to both methods to enable error handling and retry request entirely in Handle method. OnError can check RetryPolicy.RetryRequested to know whether Hanlde had called RetryPolicy.RetryAfter().

Caution: the retry will not be exactly after the specified time interval in RetryPolicy.RetryAfter(). Take into account a tolerance of around 50 milliseconds. Additionally, retry executions respect maximum concurrent handlers setting, meaning a high load can cause additional delay.

Commits

• Update unit tests project dependencies (#8) (522f6a6 by @petar-m)
• Add retry feature (6abda82 by @petar-m)
• Output unit tests and code coverage as job summary (c33eff0 by @petar-m)
• Adjust unit test wait times (195a25d by @petar-m)
• Add global using in unit tests (9f994ad by @petar-m)
• Add Directory.Build.props, enable nullable types for unit tests (4b73463 by @petar-m)
• Update GitHub actions (83c30a3 by @petar-m)
• Use ImmutableArray for event handler descriptors (573e890 by @petar-m)
• Increase wait time on unit test (6477d03 by @petar-m)
• Run Code Cleanup for solution (bb03140 by @petar-m)
• Use NullLogger when logging not configured (283e528 by @petar-m)
• Adjust unit tests wait times (887c946 by @petar-m)
• Adjust unit tests wait times (de77467 by @petar-m)
• Adjust unit tests wait times (e13d843 by @petar-m)
• Remove 'Keyed' from EventHandlerRegistryBuilder methods (2880907 by @petar-m)
• Improve EventsRecorder false positives (2cff12d by @petar-m)
• Adjust unit tests wait times (4a46a0b by @petar-m)

1.0.0

What's Changed

• Simplify EventHandlerRegistry by @petar-m in #7

Full Changelog: 1.0.0-preview3...1.0.0

1.0.0-preview3

What's Changed

• Add deferred publishing by @petar-m in #5
• Cancel deferred and pending tasks on shutdown by @petar-m in #6

Full Changelog: 1.0.0-preview2...1.0.0-preview3

1.0.0-preview2

What's Changed

• Enable separate EventBroker and event handlers registration by @petar-m in #2
• Remove EventHandlerRegistryBuilder.Add method by @petar-m in #3
• Use Guid instead of string for service key by @petar-m in #4

New Contributors

• @petar-m made their first contribution in #2

Full Changelog: 1.0.0-preview1...1.0.0-preview2

1.0.0-preview1

Initial preview release.