optimize upside-down DictionaryRow for fewer parsing alloc's

analysis/token/lowercase/lowercase.go

@@ -78,11 +78,11 @@ func toLowerDeferredCopy(s []byte) []byte {
 		// Handles the Unicode edge-case where the last
 		// rune in a word on the greek Σ needs to be converted
 		// differently.
-		if l == 'σ' && i + 2 == len(s) {
+		if l == 'σ' && i+2 == len(s) {
 			l = 'ς'
 		}
 
-  		lwid := utf8.RuneLen(l)
+		lwid := utf8.RuneLen(l)
 		if lwid > wid {
 			// utf-8 encoded replacement is wider
 			// for now, punt and defer

index/upsidedown/field_dict.go

@@ -44,7 +44,7 @@ func newUpsideDownCouchFieldDict(indexReader *IndexReader, field uint16, startTe
 	return &UpsideDownCouchFieldDict{
 		indexReader: indexReader,
 		iterator:    it,
-		dictRow:     &DictionaryRow{}, // Pre-alloced, reused row.
+		dictRow:     &DictionaryRow{},   // Pre-alloced, reused row.
 		dictEntry:   &index.DictEntry{}, // Pre-alloced, reused entry.
 		field:       field,
 	}, nil

index/upsidedown/row.go

@@ -242,9 +242,9 @@ func NewFieldRowKV(key, value []byte) (*FieldRow, error) {
 const DictionaryRowMaxValueSize = binary.MaxVarintLen64
 
 type DictionaryRow struct {
-	field uint16
 	term  []byte
 	count uint64
+	field uint16
 }
 
 func (dr *DictionaryRow) Key() []byte {
@@ -315,35 +315,20 @@ func NewDictionaryRowK(key []byte) (*DictionaryRow, error) {
 }
 
 func (dr *DictionaryRow) parseDictionaryK(key []byte) error {
-	buf := bytes.NewBuffer(key)
-	_, err := buf.ReadByte() // type
-	if err != nil {
-		return err
+	dr.field = binary.LittleEndian.Uint16(key[1:3])
+	if dr.term != nil {
+		dr.term = dr.term[:0]
 	}
-
-	err = binary.Read(buf, binary.LittleEndian, &dr.field)
-	if err != nil {
-		return err
-	}
-
-	dr.term, err = buf.ReadBytes(ByteSeparator)
-	// there is no separator expected here, should get EOF
-	if err != io.EOF {
-		return err
-	}
-
+	dr.term = append(dr.term, key[3:]...)
 	return nil
 }
 
 func (dr *DictionaryRow) parseDictionaryV(value []byte) error {
-	buf := bytes.NewBuffer(value)
-
-	count, err := binary.ReadUvarint(buf)
-	if err != nil {
-		return err
+	count, nread := binary.Uvarint(value)
+	if nread <= 0 {
+		return fmt.Errorf("DictionaryRow parse Uvarint error, nread: %d", nread)
 	}
 	dr.count = count
-
 	return nil
 }
 

search/searcher/search_disjunction.go

@@ -127,7 +127,7 @@ func (s *DisjunctionSearcher) updateMatches() error {
 				return err
 			}
 
-			last := len(s.searchers)-1
+			last := len(s.searchers) - 1
 			s.searchers[i] = s.searchers[last]
 			s.searchers = s.searchers[0:last]
 			s.currs[i] = s.currs[last]