Method listLen

posting/list.go:197–236

listLen() returns the length of the mutable layer at the readTs. If the readTs changes, the list len could change.

(readTs uint64)

// listLen() returns the length of the mutable layer at the readTs. If the readTs changes, the list len could change.
func (mm *MutableLayer) listLen(readTs uint64) int {
	if mm == nil {
		return 0
	}

	count := 0
	checkPostingForCount := func(pl *pb.PostingList) {
		for _, mpost := range pl.Postings {
			if hasDeleteAll(mpost) {
				// We reach here via either iterating the entire mutable layer, or for just the
				// current entries. For both of them we can only see the latest delete all. If a
				// posting list has a delete all marker, we still need to set count for all the other
				// entries. Hence we need to make sure that count = 0 before we reach here.
				continue
			}
			count += getLengthDelta(mpost.Op)
		}
	}

	// mm.committedUidsTime could be math.MaxUint64 or the actual value. If it's MaxUint64, we know there is no
	// entry in the mm, and we can just do iterate. If value is set and readTs < committedUidsTime, we need to
	// iterate.
	if mm.length == math.MaxInt || readTs < mm.committedUidsTime {
		mm.iterate(func(_ uint64, pl *pb.PostingList) {
			checkPostingForCount(pl)
		}, readTs)
		return count
	}

	count = mm.length

	if mm.currentEntries != nil && (readTs == mm.readTs) {
		if mm.populateDeleteAll(readTs) == mm.readTs {
			// If deleteAll is present, we don't need the count from mm.length.
			count = 0
		}
		checkPostingForCount(mm.currentEntries)
	}
	return count
}

// populateDeleteAll() returns the deleteAllMarker under readTs. It also finds out and sets the global deleteAllMarker
// in hopes to cache it and use it later if required.