func()

in v1storage/series.go [329:376]

• 42 lines of code
• 10 McCabe index (conditional complexity)

func (s *memorySeries) preloadChunks(
	indexes []int, fp model.Fingerprint, mss *MemorySeriesStorage,
) (SeriesIterator, error) {
	loadIndexes := []int{}
	pinnedChunkDescs := make([]*chunk.Desc, 0, len(indexes))
	for _, idx := range indexes {
		cd := s.chunkDescs[idx]
		pinnedChunkDescs = append(pinnedChunkDescs, cd)
		cd.Pin(mss.evictRequests) // Have to pin everything first to prevent immediate eviction on chunk loading.
		if cd.IsEvicted() {
			loadIndexes = append(loadIndexes, idx)
		}
	}
	chunk.Ops.WithLabelValues(chunk.Pin).Add(float64(len(pinnedChunkDescs)))

	if len(loadIndexes) > 0 {
		if s.chunkDescsOffset == -1 {
			panic("requested loading chunks from persistence in a situation where we must not have persisted data for chunk descriptors in memory")
		}
		chunks, err := mss.loadChunks(fp, loadIndexes, s.chunkDescsOffset)
		if err != nil {
			// Unpin the chunks since we won't return them as pinned chunks now.
			for _, cd := range pinnedChunkDescs {
				cd.Unpin(mss.evictRequests)
			}
			chunk.Ops.WithLabelValues(chunk.Unpin).Add(float64(len(pinnedChunkDescs)))
			return nopIter, err
		}
		for i, c := range chunks {
			s.chunkDescs[loadIndexes[i]].SetChunk(c)
		}
	}

	if !s.headChunkClosed && indexes[len(indexes)-1] == len(s.chunkDescs)-1 {
		s.headChunkUsedByIterator = true
	}

	curriedQuarantineSeries := func(err error) {
		mss.quarantineSeries(fp, s.metric, err)
	}

	iter := &boundedIterator{
		it:    s.newIterator(pinnedChunkDescs, curriedQuarantineSeries, mss.evictRequests),
		start: model.Now().Add(-mss.dropAfter),
	}

	return iter, nil
}