* Close subscriptions promptly
Two things:
-----------
1. Because the desired is not changed, the notifiers are not notified
that the subscription is not observing any more. So, that holds
a refernce to the subscription manager.
Address the above by setting `setDesired` to false on all subscriptions
when subscription manager closes. That will remove observer from the
notifiers.
2. When subscription manager is closed, the down track close
is invoked which flows back (with onClose callback of downtrack) to
subscription manager "handleSubscribedTrackClose". That callback
handler sets the subscribed track to nil for that subscription.
A couple of scenarios here
a. Without the above change, desired could have been true and it would
have looked that the track needs to try subscription again because
`needsSubscribe == true` (desired == true && subscribedTrack == nil)
b. Even with the change above, there is a new condition of
`desired == false && subscribedTrack == nil` and there was no handler
for that condition in the reconciler.
Address this by adding a `needsCleanup` function and delete subscription
from the map. Note that the reconciler may not be running to execute
this action as subscription manager would have closed the `closeCh`, but
doing the code in the interest of proper clean up.
* clean up
A subscription in subscription manager could live till the source
track goes away even though the participant with that subscription
is long gone due to closure on source track removal. Handle it by using
trackID to look up on source track removal.
Also, logging SDPs when a negotiation failure happens to check
if there are any mismatches.
* Perform unsubscribe in parallel to avoid blocking
When unsubscribing from tracks, we flush a blank frame in order to prepare
the transceivers for re-use. This process is blocking for ~200ms. If
the unsubscribes are performed serially, it would prevent other subscribe
operation from continuing.
This PR parallelizes that operation, and ensures subsequent subscribe
operations could reuse the existing transceivers.
* also perform in parallel when uptrack close
* fix a few log fields
* Avoid reconnect loop for unsupported downtrack
If the client subscribes to a track which codec is unsupported by the
client, sfu will trigger negotiation failed and issue a full reconnect
after received client answer. If the client try to subscribe that track
then it will got full reconnect again. That will cause a infinite
reconnect loop until the client don't subscribe that track. This PR
will unsubscribe the error track for the client and send a
SubscriptionResponse that contain the reason to indicates the track's
codec is not supported to avoid the reconnect loop.
With subscription manager, there is no need to tell a publisher
about a subscriber going away. Before subscription manager,
the up track manager of a participant (i. e. the publisher side)
was holding a list of pending subscriptions for its published tracks
and that had to be cleaned up if one of the subscriber goes away.
That is not the case any more.
Also set publisherID early so that subscription permission update has
the right publisherID. In fact, saw an empty ID in the logs and saw
that we still have the disallowed subscription handling which is not
necessary any more.
UpdateSubscription had a shortcoming where when it couldn't find the
participant, it ignored the request.
This PR further removes the reliance of current publisher state from
subscribers.
- SubscribeToTrack only takes in a trackID
- Introduced RoomTrackManager to maintain all published tracks to a room
- Added TrackUnpublished event to clearly indicate when a track has been removed
- SubscribeRequested event no longer include information about the publisher
* Return early if already subscribed.
When already subscribed, returned `subTrack` is nil.
Return early, but do not return an error.
* check for nil subTrack
* check for nil as well
Added a new manager to handle all subscription needs. Implemented using reconciler pattern. The goals are:
improve subscription resilience by separating desired state and current state
reduce complexity of synchronous processing
better detect failures with the ability to trigger full reconnect
