Add benchmark for adding images to sheet

[mlh758]

PR Details

Benchmark image adding

Description

This should help track performance regressions in future changes. I didn't want to start code to
reduce image duplication until I had a performance baseline.

Current output looks like this:
BenchmarkAddPictureFromBytes-8 10000 2205294 ns/op 373361 B/op 20358 allocs/op

Related Issue

#359

Motivation and Context

This is a first step towards future changes to this functionality.

How Has This Been Tested

This is a test :)

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.

[mlh758]

I thought the allocation count was kind of high, it looks like almost all the memory consumption is in trimSheetName

(pprof) top
Showing nodes accounting for 3562.68MB, 97.65% of 3648.40MB total
Dropped 222 nodes (cum <= 18.24MB)
Showing top 10 nodes out of 31
      flat  flat%   sum%        cum   cum%
 3419.08MB 93.71% 93.71%  3419.08MB 93.71%  github.com/360EntSecGroup-Skylar/excelize.trimSheetName
   42.63MB  1.17% 94.88%    42.63MB  1.17%  image/png.(*decoder).parsePLTE
   42.31MB  1.16% 96.04%    55.76MB  1.53%  compress/flate.NewWriter
   41.15MB  1.13% 97.17%    41.15MB  1.13%  bufio.NewReaderSize
    7.51MB  0.21% 97.38%    52.14MB  1.43%  image/png.DecodeConfig

That's probably a good target for some tinkering.

[codecov-io]

Codecov Report

Merging #367 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #367   +/-   ##
=======================================
  Coverage   97.91%   97.91%           
=======================================
  Files          21       21           
  Lines        4074     4074           
=======================================
  Hits         3989     3989           
  Misses         48       48           
  Partials       37       37

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[mlh758]

I just added another commit to this PR. trimSheetName now checks if it has any work to do before jumping in. It also pre-allocates the rune slice's capacity and breaks at a rune count of 31 instead of checking the rune count afterwards and trimming it back down. Here are the new benchmarks and profiles on my machine:

BenchmarkAddPictureFromBytes-8 10000 1170422 ns/op 12141 B/op 296 allocs/op

(pprof) top
Showing nodes accounting for 206.98MB, 79.95% of 258.88MB total
Dropped 112 nodes (cum <= 1.29MB)
Showing top 10 nodes out of 157
      flat  flat%   sum%        cum   cum%
   51.12MB 19.75% 19.75%    59.77MB 23.09%  compress/flate.NewWriter
   43.13MB 16.66% 36.41%    43.13MB 16.66%  image/png.(*decoder).parsePLTE
   41.16MB 15.90% 52.31%    41.16MB 15.90%  bufio.NewReaderSize
   22.92MB  8.86% 61.16%    22.92MB  8.86%  bytes.makeSlice
   11.04MB  4.27% 65.43%    11.04MB  4.27%  bytes.Replace

I tested this by adding a sheet with some ?:/ characters in the name and that was too long and made sure I still got a valid document.