Method buildIndex

segment.go:763–804

------------------------------------------------------ Builds and initializes the in-memory index for the segment.

(quota int, minKeyBytes int)

// Builds and initializes the in-memory index for the segment.
func (a *segment) buildIndex(quota int, minKeyBytes int) {
	if int(a.totKeyByte) < minKeyBytes {
		// Build the index only if the total key bytes is greater
		// than or equal to the SegmentKeysIndexMinKeyBytes.
		return
	}

	keyCount := a.Len()
	if keyCount == 0 {
		return // No keys to index.
	}

	keyAvgSize := int(a.totKeyByte) / keyCount

	sindex := newSegmentKeysIndex(quota, keyCount, keyAvgSize)
	if sindex == nil {
		return
	}

	scursor := &segmentCursor{
		s:   a,
		end: a.Len(),
	}

	for {
		keyIdx, key := scursor.currentKey()
		if key == nil {
			break
		}

		if !sindex.add(keyIdx, key) {
			break // Out of space.
		}

		err := scursor.nextDelta(sindex.hop)
		if err != nil {
			break
		}
	}

	a.index = sindex
}

// ------------------------------------------------------