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load.go
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load.go
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// Copyright (c) 2020 The Bluge Authors.
//
// 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 ice
import (
"encoding/binary"
"fmt"
segment "github.com/blugelabs/bluge_segment_api"
"github.com/couchbase/vellum"
)
// Open returns an impl of a segment
func Load(data *segment.Data) (segment.Segment, error) {
return load(data)
}
func load(data *segment.Data) (*Segment, error) {
footer, err := parseFooter(data)
if err != nil {
return nil, fmt.Errorf("error parsing footer: %w", err)
}
rv := &Segment{
data: data.Slice(0, data.Len()-footerLen),
footer: footer,
fieldsMap: make(map[string]uint16),
fieldDvReaders: make(map[uint16]*docValueReader),
fieldFSTs: make(map[uint16]*vellum.FST),
fieldDocs: make(map[uint16]uint64),
fieldFreqs: make(map[uint16]uint64),
}
// FIXME temporarily map to existing footer fields
// rv.memCRC = footer.crc
// rv.chunkMode = footer.chunkMode
// rv.numDocs = footer.numDocs
// rv.storedIndexOffset = footer.storedIndexOffset
// rv.fieldsIndexOffset = footer.fieldsIndexOffset
// rv.docValueOffset = footer.docValueOffset
err = rv.loadFields()
if err != nil {
return nil, err
}
err = rv.loadDvReaders()
if err != nil {
return nil, err
}
rv.updateSize()
return rv, nil
}
const fileAddrWidth = 8
func (s *Segment) loadFields() error {
// NOTE for now we assume the fields index immediately precedes
// the footer, and if this changes, need to adjust accordingly (or
// store explicit length), where s.mem was sliced from s.mm in Open().
fieldsIndexEnd := uint64(s.data.Len())
// iterate through fields index
var fieldID uint64
for s.footer.fieldsIndexOffset+(fileAddrWidth*fieldID) < fieldsIndexEnd {
addrData, err := s.data.Read(int(s.footer.fieldsIndexOffset+(fileAddrWidth*fieldID)),
int(s.footer.fieldsIndexOffset+(fileAddrWidth*fieldID)+fileAddrWidth))
if err != nil {
return err
}
addr := binary.BigEndian.Uint64(addrData)
dictLocData, err := s.data.Read(int(addr), int(fieldsIndexEnd))
if err != nil {
return err
}
dictLoc, read := binary.Uvarint(dictLocData)
n := uint64(read)
s.dictLocs = append(s.dictLocs, dictLoc)
var nameLen uint64
nameLenData, err := s.data.Read(int(addr+n), int(fieldsIndexEnd))
if err != nil {
return err
}
nameLen, read = binary.Uvarint(nameLenData)
n += uint64(read)
nameData, err := s.data.Read(int(addr+n), int(addr+n+nameLen))
if err != nil {
return err
}
n += nameLen
fieldDocData, err := s.data.Read(int(addr+n), int(fieldsIndexEnd))
if err != nil {
return err
}
fieldDocVal, read := binary.Uvarint(fieldDocData)
n += uint64(read)
fieldFreqData, err := s.data.Read(int(addr+n), int(fieldsIndexEnd))
if err != nil {
return err
}
fieldFreqVal, _ := binary.Uvarint(fieldFreqData)
name := string(nameData)
s.fieldsInv = append(s.fieldsInv, name)
s.fieldsMap[name] = uint16(fieldID + 1)
s.fieldDocs[uint16(fieldID)] = fieldDocVal
s.fieldFreqs[uint16(fieldID)] = fieldFreqVal
fieldID++
}
return nil
}