feat(alias): add DownloadConcurrency and DownloadPartSize option (#7829)

* fix(net): goroutine logic bug (AlistGo/alist#7215)

* Fix goroutine logic bug

* Fix bug

---------

Co-authored-by: hpy hs <hshpy.pengyu@gmail.com>

* perf(net): sequential and dynamic concurrency

* fix(net): incorrect error return

* feat(alias):  add `DownloadConcurrency` and `DownloadPartSize` option

* feat(net): add `ConcurrencyLimit`

* pref(net): create `chunk` on demand

* refactor

* refactor

* fix(net): `r.Closers.Add` has no effect

* refactor

---------

Co-authored-by: hpy hs <hshpy.pengyu@gmail.com>

drivers/alias/driver.go

@@ -110,6 +110,16 @@ func (d *Alias) Link(ctx context.Context, file model.Obj, args model.LinkArgs) (
 	for _, dst := range dsts {
 		link, err := d.link(ctx, dst, sub, args)
 		if err == nil {
+			if !args.Redirect && len(link.URL) > 0 {
+				// 正常情况下 多并发 仅支持返回URL的驱动
+				// alias套娃alias 可以让crypt、mega等驱动(不返回URL的) 支持并发
+				if d.DownloadConcurrency > 0 {
+					link.Concurrency = d.DownloadConcurrency
+				}
+				if d.DownloadPartSize > 0 {
+					link.PartSize = d.DownloadPartSize * utils.KB
+				}
+			}
 			return link, nil
 		}
 	}