modify cached_gc_safe_point to atomic to prevent more request to PD

[shuke987]

What problem does this PR solve?

safe_point_last_update_time is used to prevent every gc_safe_point request calling PD. But it is not atmoic, thus when getGCSafePointWithRetry calling by multiple threads, it may not worked as expected. Fix this.

Issue Number: ref #4928

Problem Summary:

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• Lloyd-Pottiger
• breezewish

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[JaySon-Huang]

https://ci.pingcap.net/blue/organizations/jenkins/tiflash-build-common/detail/tiflash-build-common/6122/pipeline

need to format the codes by using the format-diff.py script https://github.com/pingcap/tiflash#contributing

[JaySon-Huang]

I changed it to be ref #4928 cause we can avoid useless calls to PD #4928 (comment)

[breezewish]

The rest LGTM

[breezewish]

/run-all-tests

[sre-bot]

Coverage for changed files

Filename                                                                                                    Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
/home/jenkins/agent/workspace/tiflash-build-common/tiflash/dbms/src/Storages/Transaction/PDTiKVClient.h           9                 9     0.00%           1                 1     0.00%          25                25     0.00%           4                 4     0.00%
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                                                                                             9                 9     0.00%           1                 1     0.00%          25                25     0.00%           4                 4     0.00%

Coverage summary

Functions  MissedFunctions  Executed  Lines   MissedLines  Cover
18281      9730             46.78%    205105  97566        52.43%

full coverage report (for internal network access only)

[Lloyd-Pottiger]

LGTM

[flowbehappy]

/merge

[ti-chi-bot]

@flowbehappy: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 282edde

[JaySon-Huang]

LGTM

[ti-chi-bot]

@shuke987: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[sre-bot]

Coverage for changed files

Filename                                                                                                    Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
/home/jenkins/agent/workspace/tiflash-build-common/tiflash/dbms/src/Storages/Transaction/PDTiKVClient.h           9                 9     0.00%           1                 1     0.00%          25                25     0.00%           4                 4     0.00%
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                                                                                                             9                 9     0.00%           1                 1     0.00%          25                25     0.00%           4                 4     0.00%

Coverage summary

Functions  MissedFunctions  Executed  Lines   MissedLines  Cover
18322      9641             47.38%    205717  96597        53.04%

full coverage report (for internal network access only)