博客无法评论

[xiebruce]

我是在这个网站https://www.kandaoni.com/news/7733.html 来到这里的，我不知道网站站长是不是就是这个博客的开发者？目前https://www.kandaoni.com/news/7733.html 无法评论，一评论就报错

另外我对这篇文章中的download方法有疑问(新手)，download方法都是在goroutine中运行的go d.Download(resource, p)，那么该方法中return的err真的有用吗？我感觉没用吧，需要通过channel传出来才行吧？

package main
import (
    "fmt"
    "github.com/vbauerster/mpb/v5"
    "github.com/vbauerster/mpb/v5/decor"
    "io"
    "net/http"
    "os"
    "runtime"
    "strconv"
    "sync"
)
type Resource struct {
    Filename string
    Url      string
}
type Downloader struct {
    wg         *sync.WaitGroup
    pool       chan *Resource
    Concurrent int
    HttpClient http.Client
    TargetDir  string
    Resources  []Resource
}
func NewDownloader(targetDir string) *Downloader {
    concurrent := runtime.NumCPU()
    return &Downloader{
        wg:         &sync.WaitGroup{},
        TargetDir:  targetDir,
        Concurrent: concurrent,
    }
}
func (d *Downloader) AppendResource(filename, url string) {
    d.Resources = append(d.Resources, Resource{
        Filename: filename,
        Url:      url,
    })
}
func (d *Downloader) Download(resource Resource, progress *mpb.Progress) error {
    defer d.wg.Done()
    d.pool <- &resource
    finalPath := d.TargetDir + "/" + resource.Filename
    // 创建临时文件
    target, err := os.Create(finalPath + ".tmp")
    if err != nil {
        return err
    }
    // 开始下载
    req, err := http.NewRequest(http.MethodGet, resource.Url, nil)
    if err != nil {
        return err
    }
    resp, err := http.DefaultClient.Do(req)
    if err != nil {
        target.Close()
        return err
    }
    defer resp.Body.Close()
    fileSize, _ := strconv.Atoi(resp.Header.Get("Content-Length"))
    // 创建一个进度条
    bar := progress.AddBar(
        int64(fileSize),
        // 进度条前的修饰
        mpb.PrependDecorators(
            decor.CountersKibiByte("% .2f / % .2f"), // 已下载数量
            decor.Percentage(decor.WCSyncSpace),     // 进度百分比
        ),
        // 进度条后的修饰
        mpb.AppendDecorators(
            decor.EwmaETA(decor.ET_STYLE_GO, 90),
            decor.Name(" ] "),
            decor.EwmaSpeed(decor.UnitKiB, "% .2f", 60),
        ),
    )
    reader := bar.ProxyReader(resp.Body)
    defer reader.Close()
    // 将下载的文件流拷贝到临时文件
    if _, err := io.Copy(target, reader); err != nil {
        target.Close()
        return err
    }
    // 关闭临时并修改临时文件为最终文件
    target.Close()
    if err := os.Rename(finalPath+".tmp", finalPath); err != nil {
        return err
    }
    <-d.pool
    return nil
}
func (d *Downloader) Start() error {
    d.pool = make(chan *Resource, d.Concurrent)
    fmt.Println("开始下载，当前并发：", d.Concurrent)
    p := mpb.New(mpb.WithWaitGroup(d.wg))
    for _, resource := range d.Resources {
        d.wg.Add(1)
        go d.Download(resource, p)
    }
    p.Wait()
    d.wg.Wait()
    return nil
}