Broadcast channels are more suited to uBO than DOM events to dispatch
notifications to different parts of uBO.
DOM events can only be dispatched to local context, broadcast channels
dispatch to all contexts (i.e. background process, workers, auxiliary
pages) -- this last behavior is better suited to uBO to communicate
internal changes to all potential listeners, not just those in the local
context.
Additionally, broadcasting to content scripts is now done through
tabs.sendMessage() instead of through potentially opened message
ports, this simplifies broadcasting to content scripts, and this
doesn't require to have long-lived message ports in content
scripts.
Related discussion:
https://github.com/ameshkov/diffupdates
The benefits of diff-patching filter lists is much shorter update
schedule and significantly less bandwidth consumed.
At the moment, only default filter lists are subject to be
diff-patched.
External filter lists can make their lists diff-patchable by
following the specification link above.
Only filter lists fetched by the auto-updater are candidate for
diff-patching.
Forcing a manual update of the filter lists will prevent the
diff-patcher from kicking in until one or more lists are
auto-updated.
Some back-of-the-envelop calculations regarding the load on free
CDN solutions used by uBO to distribute its own filter lists:
Currently, for each CDN (with lists updating after days):
~560 M req/month, ~78 TB/month
With diff-patching lists on a 6-hour schedule:
~390 M req/month, 1 TB/month
Those estimates were done according to statistics shown by
jsDelivr, which is one of 4 CDNs picked randomly when a list
updates:
https://www.jsdelivr.com/package/gh/uBlockOrigin/uAssetsCDN?tab=stats
