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[Perfect Negotiation] Fire onnegotiationneeded when chain is empty.

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This CL generates "negotiationneeded" events if negotiation is needed
when the Operations Chain becomes empty. This is only implemented in
Unified Plan to avoid Plan B regressions (the event is pretty useless
in Plan B as it fires repeatedly).

In order to implement the spec-compliant behavior of only firing the
event when the chain is empty, this CL introduces
PeerConnectionObserver::OnNegotiationNeededEvent() and
PeerConnectionInterface::ShouldFireNegotiationNeededEvent() to allow
validating the event before firing it. This is needed because the event
must not be fired until a task has been posted and subsequently chained
operations could invalidate it in the meantime.

Test coverage is added for both legacy and modern "negotiationneeded"
events.

Bug: chromium:1060083
Change-Id: I1dbaa8f6ddb1c6e7c8abd8da3b92efcb64060383
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/180620
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31989}
This commit is contained in:
Henrik Boström
2020-08-25 10:20:11 +02:00
committed by Commit Bot
parent db724a1a23
commit e574a31c50
13 changed files with 470 additions and 76 deletions
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22
api/peer_connection_interface.h
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@ -1003,6 +1003,16 @@ class RTC_EXPORT PeerConnectionInterface : public rtc::RefCountInterface {
virtual void SetRemoteDescription(SetSessionDescriptionObserver* observer,
SessionDescriptionInterface* desc) {}
// According to spec, we must only fire "negotiationneeded" if the Operations
// Chain is empty. This method takes care of validating an event previously
// generated with PeerConnectionObserver::OnNegotiationNeededEvent() to make
// sure that even if there was a delay (e.g. due to a PostTask) between the
// event being generated and the time of firing, the Operations Chain is empty
// and the event is still valid to be fired.
virtual bool ShouldFireNegotiationNeededEvent(uint32_t event_id) {
return true;
}
virtual PeerConnectionInterface::RTCConfiguration GetConfiguration() = 0;
// Sets the PeerConnection's global configuration to |config|.
@ -1176,7 +1186,17 @@ class PeerConnectionObserver {
// Triggered when renegotiation is needed. For example, an ICE restart
// has begun.
virtual void OnRenegotiationNeeded() = 0;
// TODO(hbos): Delete in favor of OnNegotiationNeededEvent() when downstream
// projects have migrated.
virtual void OnRenegotiationNeeded() {}
// Used to fire spec-compliant onnegotiationneeded events, which should only
// fire when the Operations Chain is empty. The observer is responsible for
// queuing a task (e.g. Chromium: jump to main thread) to maybe fire the
// event. The event identified using |event_id| must only fire if
// PeerConnection::ShouldFireNegotiationNeededEvent() returns true since it is
// possible for the event to become invalidated by operations subsequently
// chained.
virtual void OnNegotiationNeededEvent(uint32_t event_id) {}
// Called any time the legacy IceConnectionState changes.
//