c09e2a08ca
And, renamed the chunk MetaData.DocID field to DocNum for naming correctness, where much of this commit is the mechanical effect of that rename.
214 lines
6.2 KiB
Go
214 lines
6.2 KiB
Go
// Copyright (c) 2017 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package zap
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"math"
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"sort"
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"github.com/blevesearch/bleve/index"
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"github.com/blevesearch/bleve/index/scorch/segment"
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"github.com/golang/snappy"
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)
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type docValueIterator struct {
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field string
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curChunkNum uint64
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numChunks uint64
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chunkLens []uint64
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dvDataLoc uint64
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curChunkHeader []MetaData
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curChunkData []byte // compressed data cache
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}
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func (di *docValueIterator) sizeInBytes() uint64 {
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// curChunkNum, numChunks, dvDataLoc --> uint64
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sizeInBytes := 24
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// field
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sizeInBytes += (len(di.field) + int(segment.SizeOfString))
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// chunkLens, curChunkHeader
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sizeInBytes += len(di.chunkLens)*8 +
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len(di.curChunkHeader)*24 +
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int(segment.SizeOfSlice*2) /* overhead from slices */
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// curChunkData is mmap'ed, not included
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return uint64(sizeInBytes)
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}
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func (di *docValueIterator) fieldName() string {
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return di.field
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}
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func (di *docValueIterator) curChunkNumber() uint64 {
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return di.curChunkNum
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}
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func (s *SegmentBase) loadFieldDocValueIterator(field string,
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fieldDvLoc uint64) (*docValueIterator, error) {
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// get the docValue offset for the given fields
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if fieldDvLoc == fieldNotUninverted {
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return nil, fmt.Errorf("loadFieldDocValueIterator: "+
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"no docValues found for field: %s", field)
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}
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// read the number of chunks, chunk lengths
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var offset, clen uint64
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numChunks, read := binary.Uvarint(s.mem[fieldDvLoc : fieldDvLoc+binary.MaxVarintLen64])
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if read <= 0 {
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return nil, fmt.Errorf("failed to read the field "+
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"doc values for field %s", field)
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}
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offset += uint64(read)
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fdvIter := &docValueIterator{
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curChunkNum: math.MaxUint64,
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field: field,
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chunkLens: make([]uint64, int(numChunks)),
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}
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for i := 0; i < int(numChunks); i++ {
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clen, read = binary.Uvarint(s.mem[fieldDvLoc+offset : fieldDvLoc+offset+binary.MaxVarintLen64])
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if read <= 0 {
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return nil, fmt.Errorf("corrupted chunk length during segment load")
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}
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fdvIter.chunkLens[i] = clen
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offset += uint64(read)
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}
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fdvIter.dvDataLoc = fieldDvLoc + offset
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return fdvIter, nil
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}
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func (di *docValueIterator) loadDvChunk(chunkNumber,
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localDocNum uint64, s *SegmentBase) error {
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// advance to the chunk where the docValues
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// reside for the given docNum
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destChunkDataLoc := di.dvDataLoc
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for i := 0; i < int(chunkNumber); i++ {
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destChunkDataLoc += di.chunkLens[i]
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}
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curChunkSize := di.chunkLens[chunkNumber]
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// read the number of docs reside in the chunk
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numDocs, read := binary.Uvarint(s.mem[destChunkDataLoc : destChunkDataLoc+binary.MaxVarintLen64])
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if read <= 0 {
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return fmt.Errorf("failed to read the chunk")
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}
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chunkMetaLoc := destChunkDataLoc + uint64(read)
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offset := uint64(0)
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di.curChunkHeader = make([]MetaData, int(numDocs))
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for i := 0; i < int(numDocs); i++ {
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di.curChunkHeader[i].DocNum, read = binary.Uvarint(s.mem[chunkMetaLoc+offset : chunkMetaLoc+offset+binary.MaxVarintLen64])
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offset += uint64(read)
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di.curChunkHeader[i].DocDvLoc, read = binary.Uvarint(s.mem[chunkMetaLoc+offset : chunkMetaLoc+offset+binary.MaxVarintLen64])
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offset += uint64(read)
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di.curChunkHeader[i].DocDvLen, read = binary.Uvarint(s.mem[chunkMetaLoc+offset : chunkMetaLoc+offset+binary.MaxVarintLen64])
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offset += uint64(read)
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}
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compressedDataLoc := chunkMetaLoc + offset
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dataLength := destChunkDataLoc + curChunkSize - compressedDataLoc
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di.curChunkData = s.mem[compressedDataLoc : compressedDataLoc+dataLength]
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di.curChunkNum = chunkNumber
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return nil
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}
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func (di *docValueIterator) visitDocValues(docNum uint64,
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visitor index.DocumentFieldTermVisitor) error {
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// binary search the term locations for the docNum
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start, length := di.getDocValueLocs(docNum)
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if start == math.MaxUint64 || length == math.MaxUint64 {
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return nil
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}
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// uncompress the already loaded data
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uncompressed, err := snappy.Decode(nil, di.curChunkData)
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if err != nil {
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return err
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}
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// pick the terms for the given docNum
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uncompressed = uncompressed[start : start+length]
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for {
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i := bytes.Index(uncompressed, termSeparatorSplitSlice)
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if i < 0 {
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break
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}
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visitor(di.field, uncompressed[0:i])
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uncompressed = uncompressed[i+1:]
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}
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return nil
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}
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func (di *docValueIterator) getDocValueLocs(docNum uint64) (uint64, uint64) {
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i := sort.Search(len(di.curChunkHeader), func(i int) bool {
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return di.curChunkHeader[i].DocNum >= docNum
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})
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if i < len(di.curChunkHeader) && di.curChunkHeader[i].DocNum == docNum {
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return di.curChunkHeader[i].DocDvLoc, di.curChunkHeader[i].DocDvLen
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}
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return math.MaxUint64, math.MaxUint64
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}
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// VisitDocumentFieldTerms is an implementation of the
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// DocumentFieldTermVisitable interface
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func (s *SegmentBase) VisitDocumentFieldTerms(localDocNum uint64, fields []string,
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visitor index.DocumentFieldTermVisitor) error {
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fieldIDPlus1 := uint16(0)
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ok := true
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for _, field := range fields {
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if fieldIDPlus1, ok = s.fieldsMap[field]; !ok {
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continue
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}
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// find the chunkNumber where the docValues are stored
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docInChunk := localDocNum / uint64(s.chunkFactor)
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if dvIter, exists := s.fieldDvIterMap[fieldIDPlus1-1]; exists &&
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dvIter != nil {
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// check if the chunk is already loaded
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if docInChunk != dvIter.curChunkNumber() {
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err := dvIter.loadDvChunk(docInChunk, localDocNum, s)
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if err != nil {
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continue
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}
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}
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_ = dvIter.visitDocValues(localDocNum, visitor)
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}
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}
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return nil
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}
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// VisitableDocValueFields returns the list of fields with
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// persisted doc value terms ready to be visitable using the
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// VisitDocumentFieldTerms method.
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func (s *Segment) VisitableDocValueFields() ([]string, error) {
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var rv []string
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for fieldID, field := range s.fieldsInv {
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if dvIter, ok := s.fieldDvIterMap[uint16(fieldID)]; ok &&
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dvIter != nil {
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rv = append(rv, field)
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}
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}
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return rv, nil
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}
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