gopdfにコントリビュートした話;メモリ使用量を最大614倍、処理時間を最大517倍向上させるFontContainer

// SubsetFontObj pdf subsetFont object
type SubsetFontObj struct {
	ttfp                  core.TTFParser
	Family                string
	CharacterToGlyphIndex *MapOfCharacterToGlyphIndex
	CountOfFont           int
	indexObjCIDFont       int
	indexObjUnicodeMap    int
	ttfFontOption         TtfOption
	funcKernOverride      FuncKernOverride
	funcGetRoot           func() *GoPdf
	addCharsBuff          []rune
}

// TTFParser true type font parser
type TTFParser struct {
	tables map[string]TableDirectoryEntry
	//head
	unitsPerEm       uint
	xMin             int
	yMin             int
	xMax             int
	yMax             int
	indexToLocFormat int
	//Hhea
	numberOfHMetrics uint
	ascender         int
	descender        int
	//end Hhea

	numGlyphs      uint
	widths         []uint
	chars          map[int]uint
	postScriptName string

	//os2
	os2Version    uint
	Embeddable    bool
	Bold          bool
	typoAscender  int
	typoDescender int
	capHeight     int
	sxHeight      int

	//post
	italicAngle        int
	underlinePosition  int
	underlineThickness int
	isFixedPitch       bool
	sTypoLineGap       int
	usWinAscent        uint
	usWinDescent       uint

	//cmap
	IsShortIndex  bool
	LocaTable     []uint
	SegCount      uint
	StartCount    []uint
	EndCount      []uint
	IdRangeOffset []uint
	IdDelta       []uint
	GlyphIdArray  []uint
	symbol        bool

	//cmap format 12
	groupingTables []CmapFormat12GroupingTable

	//data of font
	cachedFontData []byte

	//kerning
	useKerning bool //user config for use or not use kerning
	kern       *KernTable
}

func main() {
+	fontContainer := &gopdf.FontContainer{}
+	err := fontContainer.AddTTFFont("LiberationSerif-Regular", "path/to/LiberationSerif-Regular.ttf")
+	if err != nil {
+		// handle error
+	}
	pdf := &gopdf.GoPdf{}
	pdf.Start(gopdf.Config{PageSize: *gopdf.PageSizeA4})
-	err = pdf.AddTTFFont("LiberationSerif-Regular", "path/to/LiberationSerif-Regular.ttf")
+	err = pdf.AddTTFFontFromFontContainer("LiberationSerif-Regular", fontContainer)
	if err != nil {
		// handle error
	}
}

package main

import (
	"sync"

	"github.com/signintech/gopdf"
)

type UseCase struct {
	fontContainer *gopdf.FontContainer
	once          sync.Once
}

func (u *UseCase) Exec() error {
	var err error
	u.once.Do(func() {
		err = u.fontContainer.AddTTFFont("LiberationSerif-Regular", "path/to/LiberationSerif-Regular.ttf")
	})
	if err != nil {
		return err
	}

	pdf := &gopdf.GoPdf{}
	pdf.Start(gopdf.Config{PageSize: *gopdf.PageSizeA4})
	err := pdf.AddTTFFontFromFontContainer("LiberationSerif-Regular", u.fontContainer)
	if err != nil {
		return err
	}
	// PDFの生成処理
	return nil
}

go test -bench '^BenchmarkAddTTFFont.*$' -count 6 -benchmem | tee benchstat.txt
goos: linux
goarch: amd64
pkg: github.com/signintech/gopdf
cpu: AMD EPYC 7763 64-Core Processor                
BenchmarkAddTTFFontFromFontContainer-4            490024              2172 ns/op            3740 B/op         45 allocs/op
BenchmarkAddTTFFontFromFontContainer-4            531178              2356 ns/op            3740 B/op         45 allocs/op
BenchmarkAddTTFFontFromFontContainer-4            531594              2117 ns/op            3740 B/op         45 allocs/op
BenchmarkAddTTFFontFromFontContainer-4            511210              2243 ns/op            3740 B/op         45 allocs/op
BenchmarkAddTTFFontFromFontContainer-4            564414              2253 ns/op            3740 B/op         45 allocs/op
BenchmarkAddTTFFontFromFontContainer-4            502152              2160 ns/op            3740 B/op         45 allocs/op
BenchmarkAddTTFFontByReader-4                       1020           1124092 ns/op         2354553 B/op       6039 allocs/op
BenchmarkAddTTFFontByReader-4                       1033           1140968 ns/op         2353839 B/op       6039 allocs/op
BenchmarkAddTTFFontByReader-4                       1069           1276476 ns/op         2354374 B/op       6039 allocs/op
BenchmarkAddTTFFontByReader-4                       1044           1179830 ns/op         2355059 B/op       6039 allocs/op
BenchmarkAddTTFFontByReader-4                       1090           1020190 ns/op         2353677 B/op       6039 allocs/op
BenchmarkAddTTFFontByReader-4                        981           1142982 ns/op         2354842 B/op       6039 allocs/op
BenchmarkAddTTFFontData-4                           3322            371453 ns/op          359668 B/op       6011 allocs/op
BenchmarkAddTTFFontData-4                           3295            366550 ns/op          359782 B/op       6011 allocs/op
BenchmarkAddTTFFontData-4                           3276            359499 ns/op          359392 B/op       6011 allocs/op
BenchmarkAddTTFFontData-4                           3174            358636 ns/op          359632 B/op       6011 allocs/op
BenchmarkAddTTFFontData-4                           3430            364703 ns/op          359680 B/op       6011 allocs/op
BenchmarkAddTTFFontData-4                           3440            357494 ns/op          359584 B/op       6011 allocs/op
PASS
ok      github.com/signintech/gopdf     24.522s

benchstat benchstat.txt
goos: linux
goarch: amd64
pkg: github.com/signintech/gopdf
cpu: AMD EPYC 7763 64-Core Processor                
                              │ benchstat.txt │
                              │    sec/op     │
AddTTFFontFromFontContainer-4    2.208µ ±  7%
AddTTFFontByReader-4             1.142m ± 12%
AddTTFFontData-4                 362.1µ ±  3%
geomean                          97.01µ

                              │ benchstat.txt │
                              │     B/op      │
AddTTFFontFromFontContainer-4    3.652Ki ± 0%
AddTTFFontByReader-4             2.245Mi ± 0%
AddTTFFontData-4                 351.2Ki ± 0%
geomean                          143.4Ki

                              │ benchstat.txt │
                              │   allocs/op   │
AddTTFFontFromFontContainer-4      45.00 ± 0%
AddTTFFontByReader-4              6.039k ± 0%
AddTTFFontData-4                  6.011k ± 0%
geomean                           1.178k

go get -u github.com/signintech/gopdf@v0.33.0