Purging datagram queues

[gry8t]

Is it possible to purge/skip datagrams in the outgoing queue? I cant find how in documentation. Quiche for example uses purge_outgoing

Its possible that my bandwidth is lower than whats needed by my application so I need to skip datagrams to send newer ones (this is a critical feature for real time video transmission for example).

Thanks!

[djc]

quinn::Connection::send_datagram():

Transmit data as an unreliable, unordered application datagram

Application datagrams are a low-level primitive. They may be lost or delivered out of order, and data must both fit inside a single QUIC packet and be smaller than the maximum dictated by the peer.

quinn_proto::Datagrams::send():

Queue an unreliable, unordered datagram for immediate transmission

If drop is true, previously queued datagrams which are still unsent may be discarded to make space for this datagram, in order of oldest to newest. If drop is false, and there isn’t enough space due to previously queued datagrams, this function will return SendDatagramError::Blocked. Event::DatagramsUnblocked will be emitted once datagrams have been sent.

Returns Err iff a len-byte datagram cannot currently be sent.

It looks like send_datagram() sets drop to true by default, which sounds exactly like what you want?

If you want to submit a PR to improve the send_datagram() docs, that would be great!

[gry8t]

Thanks! I updated the docs but it would still be handy to have said feature, allowing to purge certain datagrams based on their content!

[djc]

Fair enough. Suggest adding a method quinn_proto::Datagrams::retain(impl Fn(&Datagram) -> bool) (below send()) which directly calls self.conn.datagrams.outgoing.retain() (and makes sure to update self.outgoing_totalwhile running). Then, add a similar retain_datagrams() to quinn::Connection.