Function OverlappingBlocks

tsdb/db.go:2152–2215

OverlappingBlocks returns all overlapping blocks from given meta files.

(bm []BlockMeta)

// OverlappingBlocks returns all overlapping blocks from given meta files.
func OverlappingBlocks(bm []BlockMeta) Overlaps {
	if len(bm) <= 1 {
		return nil
	}
	var (
		overlaps [][]BlockMeta

		// pending contains not ended blocks in regards to "current" timestamp.
		pending = []BlockMeta{bm[0]}
		// continuousPending helps to aggregate same overlaps to single group.
		continuousPending = true
	)

	// We have here blocks sorted by minTime. We iterate over each block and treat its minTime as our "current" timestamp.
	// We check if any of the pending block finished (blocks that we have seen before, but their maxTime was still ahead current
	// timestamp). If not, it means they overlap with our current block. In the same time current block is assumed pending.
	for _, b := range bm[1:] {
		var newPending []BlockMeta

		for _, p := range pending {
			// "b.MinTime" is our current time.
			if b.MinTime >= p.MaxTime {
				continuousPending = false
				continue
			}

			// "p" overlaps with "b" and "p" is still pending.
			newPending = append(newPending, p)
		}

		// Our block "b" is now pending.
		pending = append(newPending, b)
		if len(newPending) == 0 {
			// No overlaps.
			continue
		}

		if continuousPending && len(overlaps) > 0 {
			overlaps[len(overlaps)-1] = append(overlaps[len(overlaps)-1], b)
			continue
		}
		overlaps = append(overlaps, append(newPending, b))
		// Start new pendings.
		continuousPending = true
	}

	// Fetch the critical overlapped time range foreach overlap groups.
	overlapGroups := Overlaps{}
	for _, overlap := range overlaps {
		minRange := TimeRange{Min: 0, Max: math.MaxInt64}
		for _, b := range overlap {
			if minRange.Max > b.MaxTime {
				minRange.Max = b.MaxTime
			}

			if minRange.Min < b.MinTime {
				minRange.Min = b.MinTime
			}