private async Task <EventPage> fetchNextPage(long lastEncountered)
{
using (var conn = _connectionFactory.Create())
{
try
{
await conn.OpenAsync(_token).ConfigureAwait(false);
var lastPossible = lastEncountered + _options.PageSize;
var sql =
$@"
select seq_id from {_selector.Events.DatabaseSchemaName}.mt_events where seq_id > :last and seq_id <= :limit and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer order by seq_id;
{_selector.ToSelectClause(null)} where seq_id > :last and seq_id <= :limit and type = ANY(:types) and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer order by seq_id;
select min(seq_id) from {_selector.Events.DatabaseSchemaName}.mt_events where seq_id > :limit and type = ANY(:types) and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer;
select max(seq_id) from {_selector.Events.DatabaseSchemaName}.mt_events where seq_id >= :limit and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer
".Replace(" as d", "");
var cmd = conn.CreateCommand(sql)
.With("last", lastEncountered)
.With("limit", lastPossible)
.With("buffer", _settings.LeadingEdgeBuffer)
.With("types", EventTypeNames, NpgsqlDbType.Array | NpgsqlDbType.Varchar);
var page = await buildEventPage(lastEncountered, cmd).ConfigureAwait(false);
if (page.Count == 0 || page.IsSequential())
{
return(page);
}
var starting = page;
await Task.Delay(250, _token).ConfigureAwait(false);
page = await buildEventPage(lastEncountered, cmd).ConfigureAwait(false);
while (!page.CanContinueProcessing(starting.Sequences))
{
starting = page;
page = await buildEventPage(lastEncountered, cmd).ConfigureAwait(false);
}
return(page);
}
finally
{
conn.Close();
}
}
}
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));
}
public Fetcher(IDocumentStore store, DaemonSettings settings, AsyncOptions options, IDaemonLogger logger, IDaemonErrorHandler errorHandler, IEnumerable <Type> eventTypes)
{
_settings = settings;
_options = options;
_logger = logger;
_errorHandler = errorHandler;
State = FetcherState.Waiting;
// TODO -- this will have to change
_tenant = store.Tenancy.Default;
_selector = new EventSelector(store.Events, store.Advanced.Serializer);
_map = new NulloIdentityMap(store.Advanced.Serializer);
EventTypeNames = eventTypes.Select(x => store.Events.EventMappingFor(x).Alias).ToArray();
_sql =
$@"
select seq_id from {_selector.Events.DatabaseSchemaName}.mt_events where seq_id > :last and seq_id <= :limit and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer order by seq_id;
{_selector.ToSelectClause(null)} where seq_id > :last and seq_id <= :limit and type = ANY(:types) and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer order by seq_id;
select min(seq_id) from {_selector.Events.DatabaseSchemaName}.mt_events where seq_id > :limit and type = ANY(:types) and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer;
select max(seq_id) from {_selector.Events.DatabaseSchemaName}.mt_events where seq_id >= :limit and age(transaction_timestamp(), {_selector.Events.DatabaseSchemaName}.mt_events.timestamp) >= :buffer
".Replace(" as d", "");
}
