[tahoe-lafs-trac-stream] [Tahoe-LAFS] #2555: publish-and-subscribe to change events on mutables

[Tahoe-LAFS]

#2555: publish-and-subscribe to change events on mutables
---------------------+---------------------------
 Reporter:  zooko    |          Owner:  daira
     Type:  defect   |         Status:  new
 Priority:  normal   |      Milestone:  undecided
Component:  unknown  |        Version:  1.10.1
 Keywords:           |  Launchpad Bug:
---------------------+---------------------------
 Currently if a client wants to keep track of changes being made by someone
 else to a mutable, it has to poll that mutable. In Magic Folder, for
 example, we poll every few seconds. Polling is terrible! It has bad
 latency (a few seconds) and also bad load (new requests every few
 seconds).

 Instead we should implement a publish-and-subscribe notification system by
 which clients can maintain an open (but idle) connection to a server, and
 then get low-latency, cheap notifications from servers about events.

 The storage server should provide an API which does something like this:

 {{{
 remote_registerWatcher(watcher, storage_index, previous_watcher=None)
 }}}

--
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2555>
Tahoe-LAFS <https://Tahoe-LAFS.org>
secure decentralized storage