This PR adds the ability to subscribe to messages over a websocket.
To prevent polling data, the server can now push messages through the websocket, so the client can instantly update when new data is available.
The change is backwards compatible, still serving the status updates over the socket. If the client is providing the authentication token, it is auto-subscried to the legacy status message.
If the client is using the new authentication message, it needs to subscribe to get the status updates (and any other services it needs).
The event system has been extended to support new, and more accurate, events. This is the first step towards removing the general status update and the long-poll mechanism.
This also re-introduces the blocking marker, so the client can know if the operation is halted due to too many pending transfers.
Some endpoints have been moved to service implementations, to allow serving the exact same data from both endpoints and websocket.
This PR also updates the way the progress is handled, so that all transfers are returned to the client, and the transfer speeds for each transfer is calculated based on a small sample buffer, so the values are more accurate even if the program is paused during transfers.
This moves the throttle support to the StreamUtil throttled stream, which allows multiple streams to share a throttle value, such that the throttle setting is applied to the entire communication from Duplicati, and not for each connection.
This also cleans up a bit in the progress reporting, where the backend manager now keeps track of the "active" transfer and only emits progress on that. Once it finishes, a new transfer is promoted a "active".
Changed AddBackendEvent() in ResultClasses to allow the option to not update
the backend progress. This allows the BackendUploader to log the act of starting
an upload without changing the backend progress. The backend progress is now
handled by a new class, FileProgressThrottler, which will determine the transfer
rate of all uploads currently in progress.
This class also handles throttling the upload streams. The algorithm will try
to decrease or increase the streams throttle rates as appropriate by changing
the value based on the over/under amount or based on a percentage to prevent
throttling one stream directly to zero.
Kenneth Skovhede