Get length/count of out queue for producer.

Description

Really enjoying working with confluent-kafka-dotnet library, however for the life me, I can not work out how to get the length/count of out queue for a producer.

I could handle this myself by doing something like;

config.Add( "queue.buffering.max.messages", 1);

Then managing the messages to be sent using own queue, however I see very poor performance/throughput. I assume this is because it essentially negates, or at the least slows down the batch sending of messages.

Any wisdom would be very appreciated.

[matth0x1]

A rough indication of the out queue length would be much preferred over having to maintain additional code outside of the client to track the length.

[mhowlett]

I place very high priority on not confusing users 😃.

As we just discussed, it’ll be a simple change to provide another method in librdkafka that doesn’t expose librdkafka internals, and I think we should do that and not expose this number.

note to anyone reading along: rd_kafka_outq_len is an appropriate value to compare to 0 in implementing Flush, which is the reason it’s defined the way it is.