[Summer of code] Identify broker by uuid

[hzh0425]

Make sure set the target branch to develop

What is the purpose of the change

Identify broker by uuid

Brief changelog

XX

Verifying this change

XXXX

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[hzh0425]

@RongtongJin Hi, I open it again

[RongtongJin]

@hzh0425 I have created a temporary feature/controler-broker-identify branch to solve this issue. You can solve the code conflict first

[lizhanhui]

Two questions:

1. Why uuid?
2. We already have brokerId, adding a second property named brokerIdentity is very confusing. Give it another name.

[dongeforever]

@RongtongJin how about naming it as "controllerBrokerId", means it is an id for controller mode.

Just like the dledgerSelfId, controllerBrokerId may have some relation to brokerId.

when the broker is master, brokerId will be set to 0. when the broker is slave, brokerId will be set to controllerBrokerId.

the old admin command clusterList could see the value

[RongtongJin]

2. property

Hi @dongeforever , There is already a property similar to controllerBrokerId in org.apache.rocketmq.controller.impl.manager.BrokerInfo#brokerIdTable

The controllerBrokerId is currently allocated according to the IP. If the IP changes, there will be problems. So we hope to have a uuid property that can identify the broker and does not require user configuration. It will also be initialized (if not) when the broker starts and be persisted to the store directory. After that, the identity of the broker will be changed from IP to persistent uuid.

However, after your reminder, we have come up with another solution. If we persist the controllerBrokerId allocated by the controller according to the IP to the local storage of the broker when the first apply, and bring the controllerBrokerId with each request later, it seems that we can also solve the issue of IP change. For the current implementation, such changes will be slightly larger.

Currently, we prefer the second solution. What about you?

[lizhanhui]

Obviously, this pull request is sort of haste. The problem trying to solve is not new and there are better ones in the field. A numeric "node-id" suffices as long as we have a clear cluster membership algorithm in hand.

Thinking it out prior to code is always good.