Method PrefetchContents

repo/content/content_prefetch.go:57–148

PrefetchContents fetches the provided content IDs into the cache. Note that due to cache configuration, it's not guaranteed that all contents will actually be added to the cache. nolint:gocyclo

(ctx context.Context, contentIDs []ID, hint string)

//
//nolint:gocyclo
func (bm *WriteManager) PrefetchContents(ctx context.Context, contentIDs []ID, hint string) []ID {
	o := prefetchHintToOptions[hint]
	if o == nil {
		o = defaultPrefetchOptions
	}

	bm.mu.RLock()
	defer bm.mu.RUnlock()

	var (
		prefetched []ID

		// keep track of how contents we'll be fetching from each blob
		contentsByBlob = map[blob.ID][]Info{}
	)

	for _, ci := range contentIDs {
		_, bi, _ := bm.getContentInfoReadLocked(ctx, ci)
		if bi == (Info{}) {
			continue
		}

		contentsByBlob[bi.PackBlobID] = append(contentsByBlob[bi.PackBlobID], bi)
		prefetched = append(prefetched, ci)
	}

	if hint == "none" {
		return prefetched
	}

	type work struct {
		blobID    blob.ID
		contentID ID
	}

	workCh := make(chan work)

	var wg sync.WaitGroup

	go func() {
		defer close(workCh)

		for b, infos := range contentsByBlob {
			if o.shouldPrefetchEntireBlob(infos) {
				workCh <- work{blobID: b}
			} else {
				for _, bi := range infos {
					workCh <- work{contentID: bi.ContentID}
				}
			}
		}
	}()

	for range parallelFetches {
		wg.Go(func() {
			var tmp gather.WriteBuffer
			defer tmp.Close()