private async Task <EventPage> buildEventPage(long lastEncountered, NpgsqlCommand cmd)
{
IList <IEvent> events = null;
IList <long> sequences = new List <long>();
using (var reader = await cmd.ExecuteReaderAsync(_token).ConfigureAwait(false))
{
while (await reader.ReadAsync(_token).ConfigureAwait(false))
{
var seq = await reader.GetFieldValueAsync <long>(0, _token).ConfigureAwait(false);
sequences.Add(seq);
}
if (sequences.Any())
{
await reader.NextResultAsync(_token).ConfigureAwait(false);
events = await _selector.ReadAsync(reader, _map, null, _token).ConfigureAwait(false);
}
else
{
events = new List <IEvent>();
}
}
return(new EventPage(lastEncountered, sequences, events)
{
Count = events.Count
});
}
private async Task <EventPage> buildEventPage(long @from, NpgsqlCommand cmd)
{
IList <IEvent> events = null;
IList <long> sequences = new List <long>();
long nextKnown = 0;
long lastKnown = 0;
using (var reader = await cmd.ExecuteReaderAsync(_token).ConfigureAwait(false))
{
while (await reader.ReadAsync(_token).ConfigureAwait(false))
{
var seq = await reader.GetFieldValueAsync <long>(0, _token).ConfigureAwait(false);
sequences.Add(seq);
}
if (sequences.Any())
{
await reader.NextResultAsync(_token).ConfigureAwait(false);
events = await _selector.ReadAsync(reader, _map, null, _token).ConfigureAwait(false);
}
else
{
await reader.NextResultAsync(_token).ConfigureAwait(false);
events = new List <IEvent>();
}
nextKnown = await getLong(reader).ConfigureAwait(false);
lastKnown = await getLong(reader).ConfigureAwait(false);
}
return(new EventPage(@from, sequences, events)
{
Count = events.Count,
NextKnownSequence = nextKnown,
LastKnownSequence = lastKnown
});
}
public async Task <EventPage> FetchNextPage(long lastEncountered)
{
var lastPossible = lastEncountered + _options.PageSize;
var sql = $@"
select max(seq_id) from mt_events where seq_id > :last and seq_id <= :limit;
{_selector.ToSelectClause(null)} where seq_id > :last and seq_id <= :limit and type = ANY(:types) order by seq_id;
";
var cmd = _conn.CreateCommand().Sql(sql)
.With("last", lastEncountered)
.With("limit", lastPossible)
.With("types", _options.EventTypeNames, NpgsqlDbType.Array | NpgsqlDbType.Varchar);
long furthestExtant;
IList <IEvent> events = null;
using (var reader = await cmd.ExecuteReaderAsync(Cancellation).ConfigureAwait(false))
{
await reader.ReadAsync(Cancellation).ConfigureAwait(false);
furthestExtant = await reader.GetFieldValueAsync <long>(0, Cancellation).ConfigureAwait(false);
await reader.NextResultAsync(Cancellation).ConfigureAwait(false);
events = await _selector.ReadAsync(reader, _map, Cancellation).ConfigureAwait(false);
}
var streams = events.GroupBy(x => x.StreamId).Select(group =>
{
return(new EventStream(group.Key, group.OrderBy(x => x.Version).ToArray(), false));
}).ToArray();
return(new EventPage(lastEncountered, furthestExtant, streams));
}
