commit f715618eee00843441ea723f52165c6fa4ffd6f7
author Victor Boivie <boivie@webrtc.org> Tue Jul 06 21:14:51 2021
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Jul 07 13:43:59 2021
tree b56b536a47119e3ec116cabe2a76e556751f9bd8
parent 5900ba0ee8f3f9cef3b29becbb4335b8f440d57d

Use flat_map in RTCPReceiver

RTCPReceiver initially used a std::map, which made
RTCPReceiver::IncomingPacket's use of std::map represent ~0.45% CPU in
highly loaded media servers. Using std::unordered_map in change 216321
reduced it only slightly, to 0.39%.

This is the second attempt to reduce it even further. By using a
flat_map and taking advantage of the increased cache locality, the hope
is that it will be reduced. These maps generally have low cardinality
(indexed by SSRC), and are looked up often, but modified less often,
which make them a potential candidate for flat_map.

Bug: webrtc:12689
Change-Id: I6733ccf3484d1c54e661250fb6712971b80fa2a9
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/225203
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34432}