Parked: Tombstone services before sending updates #50
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Services from expired servers need to be tombstoned before informing the listeners about them.
Use the StateChangedEvent.ChangeEvent.Time to figure out if the current state of the receiver is older than the received event. We can't rely on evt.State.LastChanged for this because, when expiring a server, we get multiple events coming in on UrlListener.eventChannel and each StateChangedEvent created will contain a snapshot of the same state. This will make the receiver process only the first incoming event and drop the rest, because rcvr.CurrentState.LastChanged = evt.State.LastChanged after the first event gets processed.
relistan
reviewed
May 15, 2019
| hostname := "grendel" | ||
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| svcId1 := "deadbeef123" | ||
| service1 := service.Service{ID: svcId1, Hostname: hostname} | ||
| svcId2 := "ecgtheow" |
relistan
reviewed
May 15, 2019
| svc.Tombstone() | ||
| state.ServiceChanged(svc, previousStatus, svc.Updated) |
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You know it occurs to me that maybe we ought to be just doing this outside the loop by capturing the initial state and the final state. No one can process those intermediate changes that fast anyway.
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Hmm, I guess if anything relied on svc.Updated that would break them. Maybe there is some middle ground.
relistan
reviewed
May 15, 2019
| @@ -47,36 +50,57 @@ func Test_prepareCookieJar(t *testing.T) { | |||
| } | |||
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| func Test_Listen(t *testing.T) { | |||
| Convey("Listen()", t, func() { | |||
| Convey("Listen()", t, func(c C) { | |||
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I did not know this was a thing. Interesting.
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It's handy for testing inside goroutines, although I still haven't gotten around to fixing this bug: smartystreets/goconvey#477
relistan
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Services from expired servers need to be tombstoned before informing the listeners about them, I think :)
In
TombstoneOthersServices, we have here a similar call tostate.ServiceChanged, where the services get tombstoned first.LE: There is another problem with missed events due to having a timestamp older than the current state in the receiver, which I tried to fix in 7211a4f, but it's not going to work as is because once the first event is processed by the receiver, the receiver state will contain a timestamp that is newer than all the ChangeEvent.Time of all the other events sent when a server gets expired...