make DeltaValueSpace::info thread safe

[lidezhu]

What problem does this PR solve?

Issue Number: close #4376

Problem Summary: The info method on DeltaValueSpace access some non atomic variable without any synchronization.
Introduced by: #3943

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:

• JaySon-Huang
• JinheLin

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[lidezhu]

/run-all-tests

[JaySon-Huang]

LGTM

[lidezhu]

/run-all-tests

[JinheLin]

/merge

[ti-chi-bot]

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

/run-all-tests

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[ti-chi-bot]

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

Commit hash: 55cfdf9

[sre-bot]

Coverage for changed files

Filename                       Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
ColumnFilePersistedSet.cpp         252                63    75.00%          19                 0   100.00%         393                53    86.51%         200                59    70.50%
ColumnFilePersistedSet.h            13                 0   100.00%          10                 0   100.00%          23                 0   100.00%           2                 0   100.00%
MemTableSet.cpp                    119                24    79.83%           9                 0   100.00%         196                14    92.86%          96                25    73.96%
MemTableSet.h                        7                 0   100.00%           6                 0   100.00%          20                 0   100.00%           2                 0   100.00%
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                              391                87    77.75%          44                 0   100.00%         632                67    89.40%         300                84    72.00%

Coverage summary

Functions  MissedFunctions  Executed  Lines   MissedLines  Cover
17034      9569             43.82%    191916  97033        49.44%

full coverage report (for internal network access only)

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #4396.