4 Commits (jamesbrad/controlhttp-race-dial)

Author	SHA1	Message	Date
M. J. Fromberger	ca9d795006	util/eventbus: add a Monitor type to manage subscriber goroutines (#17127) ... A common pattern in event bus usage is to run a goroutine to service a collection of subscribers on a single bus client. To have an orderly shutdown, however, we need a way to wait for such a goroutine to be finished. This commit adds a Monitor type that makes this pattern easier to wire up: rather than having to track all the subscribers and an extra channel, the component need only track the client and the monitor. For example: cli := bus.Client("example") m := cli.Monitor(func(c *eventbus.Client) { s1 := eventbus.Subscribe[T](cli) s2 := eventbus.Subscribe[U](cli) for { select { case <-c.Done(): return case t := <-s1.Events(): processT(t) case u := <-s2.Events(): processU(u) } } }) To shut down the client and wait for the goroutine, the caller can write: m.Close() which closes cli and waits for the goroutine to finish. Or, separately: cli.Close() // do other stuff m.Wait() While the goroutine management is not explicitly tied to subscriptions, it is a common enough pattern that this seems like a useful simplification in use. Updates #15160 Change-Id: I657afda1cfaf03465a9dce1336e9fd518a968bca Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>	3 months ago
M. J. Fromberger	5b5ae2b2ee	util/eventbus: add a Done channel to the Client (#17118) ... Subscribers already have a Done channel that the caller can use to detect when the subscriber has been closed. Typically this happens when the governing Client closes, which in turn is typically because the Bus closed. But clients and subscribers can stop at other times too, and a caller has no good way to tell the difference between "this subscriber closed but the rest are OK" and "the client closed and all these subscribers are finished". We've worked around this in practice by knowing the closure of one subscriber implies the fate of the rest, but we can do better: Add a Done method to the Client that allows us to tell when that has been closed explicitly, after all the publishers and subscribers associated with that client have been closed. This allows the caller to be sure that, by the time that occurs, no further pending events are forthcoming on that client. Updates #15160 Change-Id: Id601a79ba043365ecdb47dd035f1fdadd984f303 Signed-off-by: M. J. Fromberger <fromberger@tailscale.com>	3 months ago
David Anderson	3e18434595	util/eventbus: rework to have a Client abstraction ... 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>	9 months ago
David Anderson	ef906763ee	util/eventbus: initial implementation of an in-process event bus ... Updates #15160 Signed-off-by: David Anderson <dave@tailscale.com> Co-authored-by: M. J. Fromberger <fromberger@tailscale.com>	9 months ago