Add options to the eventbus.Bus to plumb in a logger.
Route that logger in to the subscriber machinery, and trigger a log message to
it when a subscriber fails to respond to its delivered events for 5s or more.
The log message includes the package, filename, and line number of the call
site that created the subscription.
Add tests that verify this works.
Updates #17680
Change-Id: I0546516476b1e13e6a9cf79f19db2fe55e56c698
Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>
If any debugging hook might see an event, Publisher.ShouldPublish should
tell its caller to publish even if there are no ordinary subscribers.
Updates #15160
Signed-off-by: David Anderson <dave@tailscale.com>
Enables monitoring events as they flow, listing bus clients, and
snapshotting internal queues to troubleshoot stalls.
Updates #15160
Signed-off-by: David Anderson <dave@tailscale.com>
This makes the helpers closer in behavior to cancelable contexts
and taskgroup.Single, and makes the worker code use a more normal
and easier to reason about context.Context for shutdown.
Updates #15160
Signed-off-by: David Anderson <dave@tailscale.com>
The Client carries both publishers and subscribers for a single
actor. This makes the APIs for publish and subscribe look more
similar, and this structure is a better fit for upcoming debug
facilities.
Updates #15160
Signed-off-by: David Anderson <dave@tailscale.com>
