Enhancement Request: Period flush or a function call to flush BufferedMetricSink

[rohitjoshi]

Most of the application will have varying traffic and may be very lower and may not reach the buffer size. Is it possible to provide a flush() function so application can call it periodically?

[56quarters]

Hi @rohitjoshi ,
Sure, it's possible to add a flush method to the buffered sinks so that applications could periodically flush metrics. However, the buffer in the sink is only 512 bytes by default which ends up being about 10-20 metrics. If an your application isn't emitting enough metrics to fill the buffer, would the non-buffering UdpMetricSink be a better choice? Thanks!

[rohitjoshi]

@56quarters Due to the peak throughput requirement (500K+), I have increased buffer to 8196 and would like to periodically flush when volume is too low.

[56quarters]

Got it, that makes sense. I think adding a .flush() method to the MetricSink trait makes sense in this case. Would that work for your usecase?

[rohitjoshi]

👍 Thank you 🙏

[rohitjoshi]

Can you support .flush() method for StatsdClient object? I am creating StatsdClient from QueuingMetricSink where flush method not available.

let uds_sink = BufferedUnixMetricSink::with_capacity(uds_path, socket, buffer_size);
let queuing_sink = QueuingMetricSink::from(uds_sink);
let client = StatsdClient::from_sink(&conf.prefix, queuing_sink);

[56quarters]

I don't think it makes sense to add this very I/O focused method to the StatsdClient. You can solve this by keeping an Arc<dyn MetricSink + Send + Sync> around to the QueuingMetricSink in a another custom sink that wraps it and runs .flush() in a thread every N seconds or so.