public StreamSubscription(
IPublisher bus,
string streamName,
StreamRevision?startRevision,
bool resolveLinks,
ClaimsPrincipal user,
bool requiresLeader,
IReadIndex readIndex,
CancellationToken cancellationToken)
{
if (bus == null)
{
throw new ArgumentNullException(nameof(bus));
}
if (streamName == null)
{
throw new ArgumentNullException(nameof(streamName));
}
if (readIndex == null)
{
throw new ArgumentNullException(nameof(readIndex));
}
_subscriptionId = Guid.NewGuid();
_bus = bus;
_streamName = streamName;
_resolveLinks = resolveLinks;
_user = user;
_requiresLeader = requiresLeader;
_readIndex = readIndex;
_cancellationToken = cancellationToken;
_subscriptionStarted = new TaskCompletionSource <bool>();
_startRevision = startRevision == StreamRevision.End
? StreamRevision.FromInt64(readIndex.GetStreamLastEventNumber(_streamName) + 1)
: startRevision + 1 ?? StreamRevision.Start;
_inner = startRevision == StreamRevision.End
? (IStreamEnumerator) new LiveStreamSubscription(_subscriptionId, _bus, _streamName,
StreamRevision.FromInt64(readIndex.GetStreamLastEventNumber(_streamName) + 1), _resolveLinks,
_user, _requiresLeader, _subscriptionStarted, _cancellationToken)
: new CatchupStreamSubscription(_subscriptionId, bus, streamName,
startRevision + 1 ?? StreamRevision.Start, resolveLinks, user, _requiresLeader, readIndex,
_subscriptionStarted, cancellationToken);
}
public async ValueTask <bool> MoveNextAsync()
{
ReadLoop:
if (await _inner.MoveNextAsync().ConfigureAwait(false))
{
if (_inner.CurrentStreamRevision >= _startRevision)
{
return(true);
}
goto ReadLoop;
}
if (_cancellationToken.IsCancellationRequested)
{
return(false);
}
await _inner.DisposeAsync().ConfigureAwait(false);
var currentStreamRevision = _inner.CurrentStreamRevision;
Log.Verbose(
"Subscription {subscriptionId} to {streamName} reached the end at {streamRevision}, switching...",
_subscriptionId, _streamName, currentStreamRevision);
if (_inner is LiveStreamSubscription)
{
_inner = new CatchupStreamSubscription(_subscriptionId, _bus, _streamName,
currentStreamRevision, _resolveLinks, _user, _requiresLeader, _readIndex, _subscriptionStarted,
_cancellationToken);
}
else
{
_inner = new LiveStreamSubscription(_subscriptionId, _bus, _streamName, currentStreamRevision,
_resolveLinks, _user, _requiresLeader, _subscriptionStarted, _cancellationToken);
}
goto ReadLoop;
}
