private async Task HandleChangesAsync(IReadOnlyCollection <Change> changes, CancellationToken cancellationToken)
{
// This is needed bc the 'WithStartTime' isn't working for me on the ChangeFeedBuilder
// This would only be run through the first time after deleting leases container and trying to
// replay some events.
if (changes.First().TimeStamp <= _epochStartTime)
{
changes = changes.Where(x => x.TimeStamp > _epochStartTime)
.ToList().AsReadOnly();
}
foreach (var change in changes)
{
// throw new ApplicationException();
var @event = change.GetEvent(_eventTypeResolver);
var subscribedProjections = _projections
.Where(projection => projection.IsSubscribedTo(@event));
foreach (var projection in subscribedProjections)
{
var viewNames = projection.GetViewNames(change.StreamInfo.Id, @event);
foreach (var viewName in viewNames)
{
var handled = false;
while (!handled)
{
var view = await _viewRepository.LoadViewAsync(viewName);
// Only update if the LSN of the change is higher than the view. This will ensure
// that changes are only processed once.
// NOTE: This only works if there's just a single physical partition in Cosmos DB.
// TODO: To support multiple partitions we need access to the leases to store
// a LSN per lease in the view. This is not yet possible in the V3 SDK.
if (view.IsNewerThanCheckpoint(change))
{
projection.Apply(@event, view);
view.UpdateCheckpoint(change);
handled = await _viewRepository.SaveViewAsync(viewName, view);
}
else
{
// Already handled.
handled = true;
}
if (!handled)
{
// Oh noos! Somebody changed the view in the meantime, let's wait and try again.
await Task.Delay(100);
}
}
}
}
}
}
private async Task HandleChangesAsync(IReadOnlyCollection <Change> changes, CancellationToken cancellationToken)
{
foreach (var change in changes)
{
var @event = change.GetEvent(_eventTypeResolver);
var subscribedProjections = _projections
.Where(projection => projection.IsSubscribedTo(@event)).ToList();
if (subscribedProjections.Any())
{
_viewRepository = new MSSQLViewRepository(new esdemo3Context());
}
foreach (var projection in subscribedProjections)
{
var viewName = projection.GetViewName(change.StreamInfo.Id, @event);
var handled = false;
while (!handled)
{
var view = (MSSQLView)await _viewRepository.LoadViewAsync(viewName);
// Only update if the LSN of the change is higher than the view. This will ensure
// that changes are only processed once.
// NOTE: This only works if there's just a single physical partition in Cosmos DB.
// TODO: To support multiple partitions we need access to the leases to store
// a LSN per lease in the view. This is not yet possible in the V3 SDK.
if (view.IsNewerThanCheckpoint(change))
{
projection.Apply(@event, view);
view.UpdateCheckpoint(change);
handled = await _viewRepository.SaveViewAsync(viewName, view);
}
else
{
// Already handled.
handled = true;
}
if (!handled)
{
// Oh noos! Somebody changed the view in the meantime, let's wait and try again.
await Task.Delay(100);
}
}
}
}
}
public async Task ProcessChangesAsync(IChangeFeedObserverContext context, IReadOnlyList <Document> documents, CancellationToken cancellationToken)
{
foreach (var document in documents)
{
var @event = DeserializeEvent(document);
foreach (var projection in _projections)
{
if (!projection.CanHandle(@event))
{
continue;
}
var streamInfo = document.GetPropertyValue <JObject>("stream");
var viewName = projection.GetViewName(streamInfo["id"].Value <string>(), @event);
var handled = false;
while (!handled)
{
var view = await _viewRepository.LoadViewAsync(viewName);
if (view.IsNewerThanCheckpoint(context.PartitionKeyRangeId, document))
{
projection.Apply(@event, view);
view.UpdateCheckpoint(context.PartitionKeyRangeId, document);
handled = await _viewRepository.SaveViewAsync(viewName, view);
}
else
{
// Already handled.
handled = true;
}
if (!handled)
{
// Oh noos! Somebody changed the view in the meantime, let's wait and try again.
await Task.Delay(500);
}
}
}
}
}
