Fix blobstore truncate size may not right

[jiaqizho]

What problem does this PR solve?

Issue Number: close #5076 , close #5134

Problem Summary:

• DB::Exception: No enough data in file /data0/db/page/log/blobfile_6, read bytes: 0 , expected bytes: 43
• In getGcStats, BlobStore will call the getRightMargin to get the last free space and truncate the file.
• But getRightMargin will return a invalid value if last free space is not align to end.
• For example:
  • Space limit is 100. So current space is [0, 100]
  • mark a span {offset=90, size=10} as used, then the free range in SpaceMap is [0, 90).
  • Then we should get 100 when we call getRightMargin
  • But it return 0. Because in getRightMargin, we will get the last free space, and return it start.

What is changed and how it works?

• Fix the getRightMargin
• Change the log level when we do truncate.

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
• flowbehappy

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[flowbehappy]

And I think we can also add more info to this exception below. Like read_offset.
No enough data in file /data0/db/page/log/blobfile_6, read bytes: 0 , expected bytes: 4

[JaySon-Huang]

And I think we can also add more info to this exception below. Like read_offset. No enough data in file /data0/db/page/log/blobfile_6, read bytes: 0 , expected bytes: 4

@flowbehappy Already added and merged into master in this PR: https://github.com/pingcap/tiflash/pull/5094/files

[JaySon-Huang]

PTAL at this jiaqizho#1
I want to merge a one line change into this PR for more friendly log searching #5134

[JaySon-Huang]

polish some comments.

[JaySon-Huang]

LGTM

[jiaqizho]

/merge

[ti-chi-bot]

@jiaqizho: 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: fcdfb46

[sre-bot]

Coverage for changed files

Filename                        Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
BlobStore.cpp                       584               155    73.46%          56                 2    96.43%        1206               260    78.44%         368               134    63.59%
PageDirectory.cpp                   571                77    86.51%          32                 0   100.00%        1153               155    86.56%         434                93    78.57%
spacemap/SpaceMap.h                   8                 3    62.50%           4                 1    75.00%          20                 7    65.00%           8                 2    75.00%
spacemap/SpaceMapBig.h               31                11    64.52%          11                 4    63.64%          70                43    38.57%          14                 7    50.00%
spacemap/SpaceMapRBTree.cpp         346                91    73.70%          18                 0   100.00%         572               108    81.12%         202                62    69.31%
spacemap/SpaceMapRBTree.h             2                 0   100.00%           2                 0   100.00%           5                 0   100.00%           0                 0         -
spacemap/SpaceMapSTDMap.h           161                18    88.82%          11                 0   100.00%         264                17    93.56%         102                18    82.35%
tests/gtest_free_map.cpp           2506               408    83.72%          14                 0   100.00%         298                 0   100.00%         814               407    50.00%
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                              4209               763    81.87%         148                 7    95.27%        3588               590    83.56%        1942               723    62.77%

Coverage summary

Functions  MissedFunctions  Executed  Lines   MissedLines  Cover
18325      9640             47.39%    205785  96550        53.08%

full coverage report (for internal network access only)

[ti-chi-bot]

@jiaqizho: 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
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
BlobStore.cpp                       584               155    73.46%          56                 2    96.43%        1206               260    78.44%         368               134    63.59%
PageDirectory.cpp                   571                76    86.69%          32                 0   100.00%        1153               152    86.82%         434                92    78.80%
spacemap/SpaceMap.h                   8                 3    62.50%           4                 1    75.00%          20                 7    65.00%           8                 2    75.00%
spacemap/SpaceMapBig.h               31                11    64.52%          11                 4    63.64%          70                43    38.57%          14                 7    50.00%
spacemap/SpaceMapRBTree.cpp         346                91    73.70%          18                 0   100.00%         572               108    81.12%         202                62    69.31%
spacemap/SpaceMapRBTree.h             2                 0   100.00%           2                 0   100.00%           5                 0   100.00%           0                 0         -
spacemap/SpaceMapSTDMap.h           161                18    88.82%          11                 0   100.00%         264                17    93.56%         102                18    82.35%
tests/gtest_free_map.cpp           2506               408    83.72%          14                 0   100.00%         298                 0   100.00%         814               407    50.00%
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL                              4209               762    81.90%         148                 7    95.27%        3588               587    83.64%        1942               722    62.82%

Coverage summary

Functions  MissedFunctions  Executed  Lines   MissedLines  Cover
18324      9637             47.41%    205772  96537        53.09%

full coverage report (for internal network access only)

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5147.