message.
There are is a sequence where a dupe could be detected due to patching
which could lead to issues.
The sequence is
- UpdataTrackSettings with some values
- UpdateSubscription with Subcribe: false - this will patch from above
track settings
- UpdateSubscription with Subscribe: true - this will continue patching
- UpdateTrackSettings with the same settings as in the first step - this
will be declared a dupe because the track is enabled and the patched
settings will declare no change in settings.
This is okay in the current code as subscription settings are cached at
participant level and applied when somebody re-subscribes. But, that
down stream processing can change any time.
So, when processing `UpdateSubscription` message, just do not patch.
If a later `UpdateTrackSettings` comes along, let it pass even if it
is not changing anything.
* Initial commit of signal deduper.
Idea is protect against signal storm from misbehaving clients.
Design:
- SignalDeduper interface with one method to handle a SignalRequest and
return if dupe or not.
- Signal specific deduper. Could have made a single de-duper which could
handle all signal message types, but making it per type so that the
code is cleaner.
- Some module (like the router) can instantiate whatever signal types
it wants to de-dupe. When a signal message is received, that module
can run the signal message through the list of de-dupers and
potentially drop the message if any of the de-dupers declare that the
message is a dupe. Making it a list makes things a little bit
inefficient, but keeps things cleaner. Hopefully, not many de-dupers
will be needed so that the inefficiency is not pronounced.
* re-arrange comments
* helper function
* add ParticipantClosed
Raja Subramanian