AnnouncerTest sporadically fails in master in TravisCI

[drcrallen]

AnnouncerTest seems to be failing pretty regularly in TravisCI these days.

Specifically AnnouncerTest.testSessionKilled will often fail when checking the data in ZK

[drcrallen]

I looked into this a bit, and it might stem from assumptions of atomicity in the announcer. This was partially addressed in #1109 but not completely.

Curator does provide a org.apache.curator.framework.recipes.nodes.PersistentEphemeralNode which accomplishes exactly what the announcer intends to accomplish, but has two major distinctions:

1. There is no atomicity (all tasks are background tasks)
2. There is no compression like is currently enforced in the Announcer.

The Announcer probably needs re-written using the mechanism in PersistentEphemeralNode or similar.

Additionally, any place which uses the announcer probably needs assumptions of atomicity removed.

[himanshug]

this is duplicate of #2167

[drcrallen]

wouldn't 2167 be a duplicate of this one?

[himanshug]

@drcrallen ok, let me rephrase, "this is duplicated by 2167" :)