This lets debug tools list the types that clients are wielding, so
that they can build a dataflow graph and other debugging views.
Updates #15160
Signed-off-by: David Anderson <dave@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>
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>
