private async Task <SourceFilter> CreateIterativeFilterAsync(IterativeTransitOptions iterOpts, CancellationToken token)
{
var(checkpointField, offset, forcedCheckpoint) = iterOpts;
if (forcedCheckpoint != null)
{
_logger.Information("Forced to use checkpoint {ForcedCheckpoint} for collection {Collection}",
iterOpts.ForcedCheckpoint, _collectionName);
return(new SourceFilter(checkpointField, iterOpts.ForcedCheckpoint));
}
_logger.Debug("Fetching last checkpoint for collection {Collection}", _collectionName);
var lastCheckpoint = await _destination.FindLastCheckpointAsync(checkpointField, token);
if (lastCheckpoint != null)
{
#pragma warning disable CS8620
lastCheckpoint -= offset;
#pragma warning restore CS8620
_logger.Debug("Collection {Collection} will be transferred from checkpoint {LastCheckpoint}",
_collectionName, lastCheckpoint);
}
else
{
_logger.Warning("Collection {Collection} doesn't have checkpoint", _collectionName);
}
return(new SourceFilter(checkpointField, lastCheckpoint));
}