// Called by rendezvous when new remote subscriber subscribes to this stream.
private void AddSubscriber_Impl(
GuidId subscriptionId,
StreamId streamId,
IStreamConsumerExtension streamConsumer,
StreamSequenceToken token,
IStreamFilterPredicateWrapper filter)
{
StreamConsumerCollection streamDataCollection;
if (!pubSubCache.TryGetValue(streamId, out streamDataCollection))
{
streamDataCollection = new StreamConsumerCollection();
pubSubCache.Add(streamId, streamDataCollection);
}
StreamConsumerData data;
if (!streamDataCollection.TryGetConsumer(subscriptionId, out data))
{
data = streamDataCollection.AddConsumer(subscriptionId, streamId, streamConsumer, token, filter);
}
// Set cursor if not cursor is set, or if subscription provides new token
if ((data.Cursor == null || token != null) && queueCache != null)
{
data.Cursor = queueCache.GetCacheCursor(streamId.Guid, streamId.Namespace, token);
}
if (data.State == StreamConsumerDataState.Inactive)
{
RunConsumerCursor(data, filter).Ignore(); // Start delivering events if not actively doing so
}
}
// Called by rendezvous when new remote subscriber subscribes to this stream.
private async Task AddSubscriber_Impl(
GuidId subscriptionId,
StreamId streamId,
IStreamConsumerExtension streamConsumer,
StreamSequenceToken token,
IStreamFilterPredicateWrapper filter)
{
IQueueCacheCursor cursor = null;
// if not cache, then we can't get cursor and there is no reason to ask consumer for token.
if (queueCache != null)
{
try
{
StreamSequenceToken consumerToken = await streamConsumer.GetSequenceToken(subscriptionId);
// Set cursor if not cursor is set, or if subscription provides new token
consumerToken = consumerToken ?? token;
if (token != null)
{
cursor = queueCache.GetCacheCursor(streamId.Guid, streamId.Namespace, consumerToken);
}
}
catch (DataNotAvailableException dataNotAvailableException)
{
// notify consumer that the data is not available, if we can.
streamConsumer.ErrorInStream(subscriptionId, dataNotAvailableException).Ignore();
}
}
AddSubscriberToSubscriptionCache(subscriptionId, streamId, streamConsumer, cursor, filter);
}
private async Task<bool> DoHandshakeWithConsumer(
StreamConsumerData consumerData,
StreamSequenceToken cacheToken)
{
StreamHandshakeToken requestedHandshakeToken = null;
// if not cache, then we can't get cursor and there is no reason to ask consumer for token.
if (queueCache != null)
{
Exception exceptionOccured = null;
try
{
requestedHandshakeToken = await AsyncExecutorWithRetries.ExecuteWithRetries(
i => consumerData.StreamConsumer.GetSequenceToken(consumerData.SubscriptionId),
AsyncExecutorWithRetries.INFINITE_RETRIES,
(exception, i) => true,
config.MaxEventDeliveryTime,
DefaultBackoffProvider);
if (requestedHandshakeToken != null)
{
consumerData.SafeDisposeCursor(logger);
consumerData.Cursor = queueCache.GetCacheCursor(consumerData.StreamId, requestedHandshakeToken.Token);
}
else
{
if (consumerData.Cursor == null) // if the consumer did not ask for a specific token and we already have a cursor, jsut keep using it.
consumerData.Cursor = queueCache.GetCacheCursor(consumerData.StreamId, cacheToken);
}
}
catch (Exception exception)
{
exceptionOccured = exception;
}
if (exceptionOccured != null)
{
bool faultedSubscription = await ErrorProtocol(consumerData, exceptionOccured, false, null, requestedHandshakeToken != null ? requestedHandshakeToken.Token : null);
if (faultedSubscription) return false;
}
}
consumerData.LastToken = requestedHandshakeToken; // use what ever the consumer asked for as LastToken for next handshake (even if he asked for null).
// if we don't yet have a cursor (had errors in the handshake or data not available exc), get a cursor at the event that triggered that consumer subscription.
if (consumerData.Cursor == null && queueCache != null)
{
try
{
consumerData.Cursor = queueCache.GetCacheCursor(consumerData.StreamId, cacheToken);
}
catch (Exception)
{
consumerData.Cursor = queueCache.GetCacheCursor(consumerData.StreamId, null); // just in case last GetCacheCursor failed.
}
}
return true;
}
// Called by rendezvous when new remote subscriber subscribes to this stream.
private async Task AddSubscriber_Impl(
GuidId subscriptionId,
StreamId streamId,
IStreamConsumerExtension streamConsumer,
StreamSequenceToken token,
IStreamFilterPredicateWrapper filter)
{
IQueueCacheCursor cursor = null;
StreamSequenceToken requestedToken = null;
// if not cache, then we can't get cursor and there is no reason to ask consumer for token.
if (queueCache != null)
{
DataNotAvailableException errorOccured = null;
try
{
requestedToken = await streamConsumer.GetSequenceToken(subscriptionId);
// Set cursor if not cursor is set, or if subscription provides new token
requestedToken = requestedToken ?? token;
if (requestedToken != null)
{
cursor = queueCache.GetCacheCursor(streamId.Guid, streamId.Namespace, requestedToken);
}
}
catch (DataNotAvailableException dataNotAvailableException)
{
errorOccured = dataNotAvailableException;
}
if (errorOccured != null)
{
// notify consumer that the data is not available, if we can.
await OrleansTaskExtentions.ExecuteAndIgnoreException(() => streamConsumer.ErrorInStream(subscriptionId, errorOccured));
}
}
AddSubscriberToSubscriptionCache(subscriptionId, streamId, streamConsumer, cursor, requestedToken, filter);
}
private async Task RegisterStream(StreamId streamId, StreamSequenceToken firstToken, DateTime now)
{
var streamData = new StreamConsumerCollection(now);
pubSubCache.Add(streamId, streamData);
// Create a fake cursor to point into a cache.
// That way we will not purge the event from the cache, until we talk to pub sub.
// This will help ensure the "casual consistency" between pre-existing subscripton (of a potentially new already subscribed consumer)
// and later production.
var pinCursor = queueCache?.GetCacheCursor(streamId, firstToken);
try
{
await RegisterAsStreamProducer(streamId, firstToken);
}finally
{
// Cleanup the fake pinning cursor.
pinCursor?.Dispose();
}
}
public IQueueCacheCursor GetCacheCursor(Guid streamGuid, string streamNamespace, StreamSequenceToken token)
{
return(cache.GetCacheCursor(streamGuid, streamNamespace, token));
}