func()

in v1storage/persistence.go [538:581]

• 40 lines of code
• 8 McCabe index (conditional complexity)

func (p *persistence) loadChunkDescs(fp model.Fingerprint, offsetFromEnd int) ([]*chunk.Desc, error) {
	f, err := p.openChunkFileForReading(fp)
	if os.IsNotExist(err) {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	defer f.Close()

	fi, err := f.Stat()
	if err != nil {
		return nil, err
	}
	if fi.Size()%int64(chunkLenWithHeader) != 0 {
		// The returned error will bubble up and lead to quarantining of the whole series.
		return nil, fmt.Errorf(
			"size of series file for fingerprint %v is %d, which is not a multiple of the chunk length %d",
			fp, fi.Size(), chunkLenWithHeader,
		)
	}

	numChunks := int(fi.Size())/chunkLenWithHeader - offsetFromEnd
	cds := make([]*chunk.Desc, numChunks)
	chunkTimesBuf := make([]byte, 16)
	for i := 0; i < numChunks; i++ {
		_, err := f.Seek(offsetForChunkIndex(i)+chunkHeaderFirstTimeOffset, io.SeekStart)
		if err != nil {
			return nil, err
		}

		_, err = io.ReadAtLeast(f, chunkTimesBuf, 16)
		if err != nil {
			return nil, err
		}
		cds[i] = &chunk.Desc{
			ChunkFirstTime: model.Time(binary.LittleEndian.Uint64(chunkTimesBuf)),
			ChunkLastTime:  model.Time(binary.LittleEndian.Uint64(chunkTimesBuf[8:])),
		}
	}
	chunk.DescOps.WithLabelValues(chunk.Load).Add(float64(len(cds)))
	chunk.NumMemDescs.Add(float64(len(cds)))
	return cds, nil
}