public static IStatefulProjection Wrap(
ProjectionGroupStateObserver observer,
string name,
IStatefulProjection projection) =>
new StatefulProjectionBuilder(projection)
.Use(projectMidfunc: downstream => async(message, ct) =>
{
if (observer[name].Checkpoint >= message.Checkpoint)
{
return;
}
await downstream(message, ct).ConfigureAwait(false);
observer.MoveTo(name, message.Checkpoint);
})
.UseSuspendOnException(ex => observer.Suspend(name, ex))
.Build();
public static async Task LoadCheckpoints(
Func <IAsyncDocumentSession> sessionFactory,
ProjectionGroupStateObserver observer,
IEnumerable <string> keys)
{
using (var session = sessionFactory())
{
var docs = await session.LoadAsync <ProjectionPosition>(
keys.Select(ProjectionPosition.GetIdFromName)).ConfigureAwait(false);
var pairs = keys.Zip(docs, (k, d) =>
new KeyValuePair <string, AllStreamPosition>(k, AllStreamPosition.FromNullableInt64(d?.Position)));
foreach (var pair in pairs)
{
observer.MoveTo(pair.Key, pair.Value);
}
}
}
public static async Task CommitActiveCheckpoints(
Func <IAsyncDocumentSession> sessionFactory,
ProjectionGroupStateObserver observer,
CancellationToken ct)
{
if (ct.IsCancellationRequested)
{
return;
}
using (var session = sessionFactory())
{
var activePositionDocuments = observer.Active.Select(x => new ProjectionPosition
{
Id = ProjectionPosition.GetIdFromName(x),
Position = observer[x].Checkpoint.ToNullableInt64()
});
foreach (var p in activePositionDocuments)
{
await session.StoreAsync(p, ct).ConfigureAwait(false);
}
await session.SaveChangesAsync(ct).ConfigureAwait(false);
}
}
