Method Readdir

pkg/schema/dirreader.go:145–195

Readdir implements the Directory interface.

(ctx context.Context, n int)

// Readdir implements the Directory interface.
func (dr *DirReader) Readdir(ctx context.Context, n int) (entries []DirectoryEntry, err error) {
	sts, err := dr.StaticSet(ctx)
	if err != nil {
		return nil, fmt.Errorf("schema/dirreader: can't get StaticSet: %v", err)
	}
	up := dr.current + n
	if n <= 0 {
		dr.current = 0
		up = len(sts)
	} else {
		if n > (len(sts) - dr.current) {
			up = len(sts)
		}
	}

	// TODO(bradfitz): push down information to the fetcher
	// (e.g. cachingfetcher -> remote client http) that we're
	// going to load a bunch, so the HTTP client (if not using
	// SPDY) can do discovery and see if the server supports a
	// batch handler, then get them all in one round-trip, rather
	// than attacking the server with hundreds of parallel TLS
	// setups.

	type res struct {
		ent DirectoryEntry
		err error
	}
	var cs []chan res

	// Kick off all directory entry loads.
	gate := syncutil.NewGate(20) // Limit IO concurrency
	for _, entRef := range sts[dr.current:up] {
		c := make(chan res, 1)
		cs = append(cs, c)
		gate.Start()
		go func(entRef blob.Ref) {
			defer gate.Done()
			entry, err := NewDirectoryEntryFromBlobRef(ctx, dr.fetcher, entRef)
			c <- res{entry, err}
		}(entRef)
	}

	for _, c := range cs {
		res := <-c
		if res.err != nil {
			return nil, fmt.Errorf("schema/dirreader: can't create dirEntry: %v", res.err)
		}
		entries = append(entries, res.ent)
	}
	return entries, nil
}