Interface IProjectionProgress

Namespace

Stratara.Abstractions.Projections

Assembly

Stratara.Abstractions.dll

Lets a host wait until a projection that reads the store from a checkpoint has applied what was committed: take a StoreMark once the write has committed, then wait for the projection to reach it before reading its read model.

public interface IProjectionProgress

Extension Methods

FieldChangedEventExtensions.ApplyPropertyChanged<TAggregate>(TAggregate, FieldChangedEvent<TAggregate>)

EventStream.ApplyEvents(object, IReadOnlyList<IEvent>)

Examples

await mediator.HandleAsync(command, cancellationToken);
var mark = await progress.MarkAsync([command.OrderId], cancellationToken);
var result = await progress.WaitAsync(typeof(OrdersProjection), mark, TimeSpan.FromSeconds(5), cancellationToken);
if (!result.IsReached)
{
    // refuse with "try again", or answer without the read
}

Methods

MarkAsync(IEnumerable<Guid>, CancellationToken)

Takes a mark that covers every entry committed to streamIds at the time of the call, and constrains only the partitions those streams fall into: a wait for it is not held up by any other partition. Take it after the commit whose effect the host wants to read; a decision that needs everything committed, across streams the host did not write, takes MarkAsync(CancellationToken) instead.

Task<StoreMark> MarkAsync(IEnumerable<Guid> streamIds, CancellationToken cancellationToken = default)

Parameters

streamIds IEnumerable<Guid>

The streams the host committed to.

cancellationToken CancellationToken

Propagated to the store.

Returns

Task<StoreMark>

The mark, to be passed back to WaitAsync(string, StoreMark, TimeSpan, CancellationToken).

Remarks

The default answers MarkAsync(CancellationToken), which covers more and so keeps the promise; an implementation that knows its partitions narrows it.

Exceptions

ArgumentNullException

streamIds is null.

ArgumentException

streamIds names no stream (the framework's implementation).

MarkAsync(CancellationToken)

Takes a mark that covers every entry committed at the time of the call, in every partition — an entry that is committed while another write is still open included. An entry whose transaction commits afterwards is not covered.

Task<StoreMark> MarkAsync(CancellationToken cancellationToken = default)

Parameters

cancellationToken CancellationToken

Propagated to the store.

Returns

Task<StoreMark>

The mark, to be passed back to WaitAsync(string, StoreMark, TimeSpan, CancellationToken).

WaitAsync(string, StoreMark, TimeSpan, CancellationToken)

Waits until the projection has applied every entry mark covers, in every partition, or until timeout has passed. A partition stopped at an entry does not end the wait early, because a retry may still apply the entry in time; a rebuild or a full replay during the wait is waited through.

Task<ProjectionWaitResult> WaitAsync(string projectionName, StoreMark mark, TimeSpan timeout, CancellationToken cancellationToken = default)

Parameters

projectionName string

The projection, by the name the framework gives it.

mark StoreMark

A mark taken with MarkAsync(CancellationToken) or MarkAsync(IEnumerable<Guid>, CancellationToken).

timeout TimeSpan

How long to wait at most; Zero answers without waiting.

cancellationToken CancellationToken

Ends the wait without an answer.

Returns

Task<ProjectionWaitResult>

Reached once the projection has applied the mark's entries; otherwise why it has not, with the partitions that are behind.

Exceptions

InvalidOperationException

No projection of that name is registered.

ArgumentOutOfRangeException

timeout is negative.

OperationCanceledException

cancellationToken was cancelled.

WaitAsync(Type, StoreMark, TimeSpan, CancellationToken)

Waits until the projection of projectionType has applied every entry mark covers; otherwise as WaitAsync(string, StoreMark, TimeSpan, CancellationToken).

Task<ProjectionWaitResult> WaitAsync(Type projectionType, StoreMark mark, TimeSpan timeout, CancellationToken cancellationToken = default)

Parameters

projectionType Type

The type of a registered projection.

mark StoreMark

A mark taken with MarkAsync(CancellationToken) or MarkAsync(IEnumerable<Guid>, CancellationToken).

timeout TimeSpan

How long to wait at most; Zero answers without waiting.

cancellationToken CancellationToken

Ends the wait without an answer.

Returns

Task<ProjectionWaitResult>

Whether the projection reached the mark, and if not, why and in which partitions.

Exceptions

InvalidOperationException

No projection of that type is registered.

ArgumentOutOfRangeException

timeout is negative.

OperationCanceledException

cancellationToken was cancelled.