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- // Copyright (c) 2017 Couchbase, Inc.
- //
- // Licensed under the Apache License, Version 2.0 (the "License");
- // you may not use this file except in compliance with the License.
- // You may obtain a copy of the License at
- //
- // http://www.apache.org/licenses/LICENSE-2.0
- //
- // Unless required by applicable law or agreed to in writing, software
- // distributed under the License is distributed on an "AS IS" BASIS,
- // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- // See the License for the specific language governing permissions and
- // limitations under the License.
-
- package zap
-
- import (
- "bytes"
- "encoding/binary"
- "fmt"
- "math"
- "sort"
-
- "github.com/blevesearch/bleve/index"
- "github.com/blevesearch/bleve/index/scorch/segment"
- "github.com/golang/snappy"
- )
-
- type docValueIterator struct {
- field string
- curChunkNum uint64
- numChunks uint64
- chunkLens []uint64
- dvDataLoc uint64
- curChunkHeader []MetaData
- curChunkData []byte // compressed data cache
- }
-
- func (di *docValueIterator) sizeInBytes() uint64 {
- // curChunkNum, numChunks, dvDataLoc --> uint64
- sizeInBytes := 24
-
- // field
- sizeInBytes += (len(di.field) + int(segment.SizeOfString))
-
- // chunkLens, curChunkHeader
- sizeInBytes += len(di.chunkLens)*8 +
- len(di.curChunkHeader)*24 +
- int(segment.SizeOfSlice*2) /* overhead from slices */
-
- // curChunkData is mmap'ed, not included
-
- return uint64(sizeInBytes)
- }
-
- func (di *docValueIterator) fieldName() string {
- return di.field
- }
-
- func (di *docValueIterator) curChunkNumber() uint64 {
- return di.curChunkNum
- }
-
- func (s *SegmentBase) loadFieldDocValueIterator(field string,
- fieldDvLoc uint64) (*docValueIterator, error) {
- // get the docValue offset for the given fields
- if fieldDvLoc == fieldNotUninverted {
- return nil, fmt.Errorf("loadFieldDocValueIterator: "+
- "no docValues found for field: %s", field)
- }
-
- // read the number of chunks, chunk lengths
- var offset, clen uint64
- numChunks, read := binary.Uvarint(s.mem[fieldDvLoc : fieldDvLoc+binary.MaxVarintLen64])
- if read <= 0 {
- return nil, fmt.Errorf("failed to read the field "+
- "doc values for field %s", field)
- }
- offset += uint64(read)
-
- fdvIter := &docValueIterator{
- curChunkNum: math.MaxUint64,
- field: field,
- chunkLens: make([]uint64, int(numChunks)),
- }
- for i := 0; i < int(numChunks); i++ {
- clen, read = binary.Uvarint(s.mem[fieldDvLoc+offset : fieldDvLoc+offset+binary.MaxVarintLen64])
- if read <= 0 {
- return nil, fmt.Errorf("corrupted chunk length during segment load")
- }
- fdvIter.chunkLens[i] = clen
- offset += uint64(read)
- }
-
- fdvIter.dvDataLoc = fieldDvLoc + offset
- return fdvIter, nil
- }
-
- func (di *docValueIterator) loadDvChunk(chunkNumber,
- localDocNum uint64, s *SegmentBase) error {
- // advance to the chunk where the docValues
- // reside for the given docNum
- destChunkDataLoc := di.dvDataLoc
- for i := 0; i < int(chunkNumber); i++ {
- destChunkDataLoc += di.chunkLens[i]
- }
-
- curChunkSize := di.chunkLens[chunkNumber]
- // read the number of docs reside in the chunk
- numDocs, read := binary.Uvarint(s.mem[destChunkDataLoc : destChunkDataLoc+binary.MaxVarintLen64])
- if read <= 0 {
- return fmt.Errorf("failed to read the chunk")
- }
- chunkMetaLoc := destChunkDataLoc + uint64(read)
-
- offset := uint64(0)
- di.curChunkHeader = make([]MetaData, int(numDocs))
- for i := 0; i < int(numDocs); i++ {
- di.curChunkHeader[i].DocNum, read = binary.Uvarint(s.mem[chunkMetaLoc+offset : chunkMetaLoc+offset+binary.MaxVarintLen64])
- offset += uint64(read)
- di.curChunkHeader[i].DocDvLoc, read = binary.Uvarint(s.mem[chunkMetaLoc+offset : chunkMetaLoc+offset+binary.MaxVarintLen64])
- offset += uint64(read)
- di.curChunkHeader[i].DocDvLen, read = binary.Uvarint(s.mem[chunkMetaLoc+offset : chunkMetaLoc+offset+binary.MaxVarintLen64])
- offset += uint64(read)
- }
-
- compressedDataLoc := chunkMetaLoc + offset
- dataLength := destChunkDataLoc + curChunkSize - compressedDataLoc
- di.curChunkData = s.mem[compressedDataLoc : compressedDataLoc+dataLength]
- di.curChunkNum = chunkNumber
- return nil
- }
-
- func (di *docValueIterator) visitDocValues(docNum uint64,
- visitor index.DocumentFieldTermVisitor) error {
- // binary search the term locations for the docNum
- start, length := di.getDocValueLocs(docNum)
- if start == math.MaxUint64 || length == math.MaxUint64 {
- return nil
- }
- // uncompress the already loaded data
- uncompressed, err := snappy.Decode(nil, di.curChunkData)
- if err != nil {
- return err
- }
-
- // pick the terms for the given docNum
- uncompressed = uncompressed[start : start+length]
- for {
- i := bytes.Index(uncompressed, termSeparatorSplitSlice)
- if i < 0 {
- break
- }
-
- visitor(di.field, uncompressed[0:i])
- uncompressed = uncompressed[i+1:]
- }
-
- return nil
- }
-
- func (di *docValueIterator) getDocValueLocs(docNum uint64) (uint64, uint64) {
- i := sort.Search(len(di.curChunkHeader), func(i int) bool {
- return di.curChunkHeader[i].DocNum >= docNum
- })
- if i < len(di.curChunkHeader) && di.curChunkHeader[i].DocNum == docNum {
- return di.curChunkHeader[i].DocDvLoc, di.curChunkHeader[i].DocDvLen
- }
- return math.MaxUint64, math.MaxUint64
- }
-
- // VisitDocumentFieldTerms is an implementation of the
- // DocumentFieldTermVisitable interface
- func (s *SegmentBase) VisitDocumentFieldTerms(localDocNum uint64, fields []string,
- visitor index.DocumentFieldTermVisitor) error {
- fieldIDPlus1 := uint16(0)
- ok := true
- for _, field := range fields {
- if fieldIDPlus1, ok = s.fieldsMap[field]; !ok {
- continue
- }
- // find the chunkNumber where the docValues are stored
- docInChunk := localDocNum / uint64(s.chunkFactor)
-
- if dvIter, exists := s.fieldDvIterMap[fieldIDPlus1-1]; exists &&
- dvIter != nil {
- // check if the chunk is already loaded
- if docInChunk != dvIter.curChunkNumber() {
- err := dvIter.loadDvChunk(docInChunk, localDocNum, s)
- if err != nil {
- continue
- }
- }
-
- _ = dvIter.visitDocValues(localDocNum, visitor)
- }
- }
- return nil
- }
-
- // VisitableDocValueFields returns the list of fields with
- // persisted doc value terms ready to be visitable using the
- // VisitDocumentFieldTerms method.
- func (s *Segment) VisitableDocValueFields() ([]string, error) {
- var rv []string
- for fieldID, field := range s.fieldsInv {
- if dvIter, ok := s.fieldDvIterMap[uint16(fieldID)]; ok &&
- dvIter != nil {
- rv = append(rv, field)
- }
- }
- return rv, nil
- }
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