This CL makes OutstandingData keep track of chunks that are eligible for
fast retransmission. When the socket goes into fast recovery, the
reported missing chunks can be retransmitted quickly (ignoring the
congestion window) according to
https://datatracker.ietf.org/doc/html/rfc4960#section-7.2.4.
The CL also adds the new API to OutstandingData to retrieve only the
chunks that are eligible for fast retransmission, and moves the
remaining chunks to the ordinary list of chunks to be retransmitted
later.
This solves an issue where the retransmission timer wouldn't start if
there wouldn't be any chunks to fast-retransmit.
It doesn't, however, make sure that chunks that should be fast
retransmitted can send even when the congestion window is full. That
will be solved in the follow-up CL.
Bug: webrtc:13969
Change-Id: If4012d1cb284ef4a2d815683ed60cbbbff5b3c3b
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/259865
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36721}
a5fecb3917