tidb-server: close Domain and Storage before HTTP listener

[coocood]

What problem does this PR solve?

If the tidb-server failed to quit, we need to know why.
But HTTP listener is closed before domain and storage, we can get the goroutine stack info.
It can be helpful to solve #7545

What is changed and how it works?

add SetCleanupFunc method to Server, call this function in Close before HTTP listener is closed.

Check List

Tests

• Manual test (add detailed scripts or steps below)

1. Add Sleep(time.Munite) in cleanup.
2. make server
3. start the server
4. kill the server.
5. try to connect the server with mysql-client, should be failed.
6. visit http://localhost:10080/debug/pprof, we can see the page.

Code changes

• Has exported function/method change

[coocood]

@crazycs520 @tiancaiamao PTAL

[tiancaiamao]

I don't think the change works. @coocood
As long as TiDB receive a signal, server is closed:
https://github.com/pingcap/tidb/pull/7558/files#diff-af2c9279ed41f7023f9b6b73cba2d18fL453

Then status listening port is closed:
https://github.com/pingcap/tidb/pull/7558/files#diff-91bbeda7eb98a7adc57b9e47e2cf5c2bR305

[coocood]

@tiancaiamao
It works, you can try manual test steps.

[tiancaiamao]

Oh, I see. The exit sequence:

• get signal
• signal handle will call server.Close
• clean up function in server.Close
• the clean up function will close domain [store and domain close]
• server.Close close the stats listening handle after clean up is done [http listener close]

LGTM

[lysu]

To get goroutine, how about add a new signal handler(e.g. kill -USR1, in jvm we use kill -3) and then call pprof.Lookup("goroutine") write result to stdout or log at last, instead of close port? 😆

shutdown port first is common, because we don't know whether http api will do some important jobs in furture, close port in last maybe break those jobs during shutdown process logic.

[coocood]

@lysu
Good point!
You can write a PR for it, then this can be closed.