Optimize ColumnNumberToName function performance, reduce about 50% memory usage and 50% time cost

[zhayt]

PR Details

Optimizing memory usage by pre-allocation.

Description

1. ColumnNumberToName Function:

   • The ColumnNumberToName function previously concatenated rows using the + operator, leading to significant memory allocation when called frequently.
   • The function now uses a pre-allocated slice to build the Excel column name. During construction, the converted number to letter is added to this slice. At the end, the slice of runes is converted to a string and returned.

2. Sheet Pre-allocation:

   • Added an option to create a Sheet with pre-allocated rows.
   • The xlsxWorksheet structure now contains a field with a slice type. When calling the SetCell... function to add a row to the sheet, it in turn calls the prepareSheetXML function. This function adds an xlsxRow structure to the slice.
   • Previously, multiple calls to prepareSheetXML caused the slice to grow, allocating a lot of memory and performing unnecessary copying. The new approach pre-allocates the maximum number of rows, reducing memory allocations and copying overhead.

Related Issue

• Resolves Issue #XXX

Motivation and Context

• When working with a lot of data, some functions create many objects and trigger garbage collection (GC). The GC then loads the processor.
• This optimization reduces memory allocations and the associated GC overhead, improving performance.

How Has This Been Tested

• The changes have been tested in a development environment with datasets of varying sizes.
• Benchmark tests were added to measure performance improvements in memory usage and processing time.
• Existing unit tests were run to ensure no regressions were introduced.

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

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Feel free to modify any part of this to better fit your needs!

[xuri]

Thanks for your PR. I've left some comments.

[xuri]

I suggest that we separate these two improvements into 2 PRs, and I will take a reconsider about the design of reallocate rows for worksheets.

[zhayt]

Sure, I will separate these two changes into different PRs. Do I need to create two new PRs, or can I keep the changes related to the ColumnNumberToName function in this PR?

Thanks for reviewing!

[xuri]

You can keep the changes related to the ColumnNumberToName function in this PR. Thanks.

[zhayt]

Done, I left in this PR only the changes related to the ColumnNumberToName function. Thanks.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.30%. Comparing base (4e6457a) to head (d4e406e).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1935   +/-   ##
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  Coverage   99.30%   99.30%           
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  Files          32       32           
  Lines       24961    24965    +4     
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+ Hits        24787    24791    +4     
  Misses         93       93           
  Partials       81       81           

Flag	Coverage Δ
unittests	99.30% <100.00%> (+<0.01%)	⬆️

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[xuri]

LGTM, thanks for your contribution.