Update bundle-cache on split-bundle and avoid disabling main bundle

[rdhabalia]

Motivation

As described at #821 : Lookup fails after bundle-split.
I am able to reproduce with 2 brokers and with SimpleLoadManagerImpl enabled.

1. Broker-2 receives a lookup request for a brand-new namespace (which doesn't have local-policies), so, broker-2 creates local-policies, puts bundle data into bundlesCache, and assigns bundle to Broker-1.
2. Now, Broker-1 splits bundle, disable original bundle and updates local-policies.
3. Broker-2 doesn't know about newly split bundle and original bundle is disable. So, any lookup request for this bundle on broker-2 will receive above error.

Modifications

1. Set the watch for local-policies and invalidate BundleCache when watch triggers.
2. Don't disable original bundle and let it be enabled so, if any other broker which didn't receive watch, can still think that bundle is enabled and redirect the request to original broker. It will do two things:

• Lookup will not fail on broker which didn't receive request and it redirects to original broker
• Original broker knows in which bundle that topic falls and serves request accordingly.

Result

It will fix lookup-failure for split-bundle.

[merlimat]

Is this needed, or just a safety measure to have the parent bundle to be still "active" in case other brokers don't have the local cache updated yet?

[rdhabalia]

yes, that protection may need while broker is refreshing cache (invalidate old bundle and assign topic-ownership to new bundles). So, I will add that protection again by disabling namespace in memory only but other broker can still redirect to this broker.

[merlimat]

👍