如何以goroutine的身份运行filepath.Walkfunc

Question

I'm trying to parse a large image dataset. I'm using filepath.Walk ]and processing each file I find there. I'd like the filepath.

package main

import (
    "fmt"
    "image/color"
    "image/png"
    "math/rand"
    "os"
)

var (
    Black = color.Gray{0}
)

func getRandFloatNumber(min, max float32) float32 {
    return (rand.Float32()*2 - min) * max
}

func openImage(path string, info os.FileInfo, err error) error {
    infile, _ := os.Open(path)
    defer infile.Close()
    img, err := png.Decode(infile)
    if err != nil {
        return nil
    }

    array := make([]float32, 128*128)
    for y := 0; y < 128; y++ {
        for x := 0; x < 128; x++ {
            c := color.GrayModel.Convert(img.At(x, y)).(color.Gray)
            if c == Black {
                array[x*y] = getRandFloatNumber(0.7, 0.95)
            } else {
                array[x*y] = getRandFloatNumber(0.1, 0.25)
            }
        }
    }

    fmt.Println(info.Name())

    return nil
}

How to run openImage as a gorutine? Or how to optimize this code?

Answer 1

You can't get filepath.Walk to call your function in a goroutine, but you can simply start a goroutine in your WalkFunc.

package main

import (
    "os"
    "path/filepath"
)

func main() {
    filepath.Walk("/my/dir", func(path string, info os.FileInfo, err error) error {
            if err != nil {
                    return err
            }

            if info.IsDir() {
                    return nil
            }

            // Check more criteria if necessary. Also consider limiting the number
            // of concurrent goroutines.

            go openImage(path, info)

            return nil
    })
}

func openImage(path string, info os.FileInfo) {
}