private async Task SendIfAny(
string category,
IEventStoreContext context,
NpgsqlConnection connection)
{
bool hasMoreStreams;
do
{
var streamsInOutbox = await GetTopOfOutboxStreams(connection);
hasMoreStreams = streamsInOutbox.Count == MaxStreamsPerRead;
foreach (var id in streamsInOutbox)
{
var stream = new StreamId(category, id);
var lockId = stream.GetLockId();
if (await TryLock(lockId, connection))
{
var events = await GetEvents(stream, connection);
if (events.Count == 0)
{
await Unlock(lockId, connection);
continue;
}
var operation = new SendingOperation(
stream,
lockId,
events,
connection,
context.GetPublisher(stream));
await operation.SendAsync();
}
}
} while (hasMoreStreams);
}
public async Task <ISendingOperation> PrepareSendingAsync(
StreamId stream,
IReadOnlyCollection <RecordedEvent> events,
NpgsqlConnection connection,
NpgsqlTransaction transaction)
{
if (events.Count == 0)
{
throw new ArgumentException("Events is empty", nameof(events));
}
var streamLock = stream.GetLockId();
long lastSentEventNumber;
await using (var prepareSending = BuildPrepareCommand(stream, streamLock, connection, transaction))
{
await prepareSending.PrepareAsync();
await using var reader = await prepareSending.ExecuteReaderAsync();
await reader.NextResultAsync();
await reader.ReadAsync();
lastSentEventNumber = reader.GetInt64(0);
}
var startSendFrom = lastSentEventNumber + 1;
if (events.First().Number == startSendFrom)
{
return(new SendingOperation(
stream,
streamLock,
events,
connection,
_context.GetPublisher(stream)));
}
var readResult = await _reader.ReadStreamEventsForwardAsync(
stream,
startSendFrom,
int.MaxValue,
connection,
transaction);
ValidateReadResult(readResult, startSendFrom, events.Count);
events = readResult.Events;
return(new SendingOperation(stream, streamLock, events, connection, _context.GetPublisher(stream)));
void ValidateReadResult(EventSliceReadResult result, long firstEventNumber, int prevEventsCount)
{
if (result.Status != ReadStatus.Success)
{
throw new InvalidOperationException($"Events read status is {result.Status}");
}
if (result.Events.First().Number != firstEventNumber)
{
throw new InvalidOperationException(
$"First event must have number {firstEventNumber} but had {result.Events.First().Number}");
}
if (result.Events.Count <= prevEventsCount)
{
throw new InvalidOperationException(
$"Expected events count must be greater then {prevEventsCount}");
}
}
}