/// <summary>
/// Gets an observable sequence of any changes to the Fetcher for a specific topic/partition.
/// </summary>
/// <param name="topic"></param>
/// <param name="partitionId"></param>
/// <param name="consumerConfiguration"></param>
/// <returns></returns>
internal IObservable<Fetcher> GetFetcherChanges(string topic, int partitionId, ConsumerConfiguration consumerConfiguration)
{
return PartitionStateChanges
.Where(t => t.Topic == topic && t.PartitionId == partitionId)
.Select(state =>
{
// if the state is not ready, return NULL for the fetcher.
if (!state.ErrorCode.IsSuccess())
return (Fetcher)null;
// get or create the correct Fetcher for this topic/partition
var broker = FindBrokerMetaForPartitionId(state.Topic, state.PartitionId);
var fetcher = _activeFetchers.GetOrAdd(broker, b =>
{
// all new fetchers need to be "watched" for errors.
var f = new Fetcher(this, b, _protocol, consumerConfiguration, _cancel.Token);
// subscribe to error and complete notifications, and remove from active fetchers
f.ReceivedMessages.Subscribe(_ => { },
err =>
{
_log.Warn("Received error from fetcher {0}. Removing from active fetchers.", f);
Fetcher ef;
_activeFetchers.TryRemove(broker, out ef);
},
() =>
{
_log.Info("Received complete from fetcher {0}. Removing from active fetchers.", f);
Fetcher ef;
_activeFetchers.TryRemove(broker, out ef);
});
return f;
});
return fetcher;
})
.Do(f => _log.Debug("GetFetcherChanges returning {1} fetcher {0}", f, f == null ? "null" : "new"),
ex => _log.Error(ex, "GetFetcherChages saw ERROR returning new fetcher."),
() => _log.Error("GetFetcherChanges saw COMPLETE from returning new fetcher."));
}
