executer: add Cop_time in slow log (#16873)

[sre-bot]

cherry-pick #16873 to release-4.0

---

What problem does this PR solve?

Before this PR, TiDB Slow log only record Process_time, but it is the total process time of cop task spend on TiKV, we still don't know the related Cop_time spend in tidb, as below:

What is changed and how it works?

Add Cop_time in slow_query and slow log. The Cop_time contain the time duration as below:

• Send Cop request.
• Send request to TiKV network latency duration.
• TiKV handle cop request duration.
• Send result to TiDB network latency.
• Recieve result latency.
• If meet error, maybe retry upper steps.

mysql>select query_time,cop_time,query from `CLUSTER_SLOW_QUERY` where cop_time>0 limit 3;
+-------------+-------------+---------------------------------------------------------------------------------------------------+
| query_time  | cop_time    | query                                                                                             |
+-------------+-------------+---------------------------------------------------------------------------------------------------+
| 0.382663125 | 0.382427668 | select count(*) from t2;                                                                          |
| 0.329472658 | 0.329190264 | select count(*) from t2;                                                                          |
| 0.929105778 | 0.400684833 | select count(*) from t2 where c2 >=0 and c1 in (select c1 from t2 where c7!=now()) and c8!=now(); |
+-------------+-------------+---------------------------------------------------------------------------------------------------+

Related changes

• Need to cherry-pick to the release branch

Check List

Tests

• Unit test

Side effects

• Performance regression
  • Consumes more CPU
  • Consumes more MEM

Release note

[sre-bot]

/run-all-tests

[djshow832]

LGTM

[qw4990]

LGTM

[bb7133]

/merge

[sre-bot]

/run-all-tests

[sre-bot]

@sre-bot merge failed.

[crazycs520]

/run-integration-copr-test

[zz-jason]

/merge

[sre-bot]

Your auto merge job has been accepted, waiting for:

• 16907

[sre-bot]

/run-all-tests

[sre-bot]

@sre-bot merge failed.