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indexes.go
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indexes.go
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// _ _
// __ _____ __ ___ ___ __ _| |_ ___
// \ \ /\ / / _ \/ _` \ \ / / |/ _` | __/ _ \
// \ V V / __/ (_| |\ V /| | (_| | || __/
// \_/\_/ \___|\__,_| \_/ |_|\__,_|\__\___|
//
// Copyright © 2016 - 2024 Weaviate B.V. All rights reserved.
//
// CONTACT: hello@weaviate.io
//
package segmentindex
import (
"bufio"
"bytes"
"encoding/binary"
"io"
"os"
"path/filepath"
"sort"
"github.com/pkg/errors"
)
type Indexes struct {
Keys []Key
SecondaryIndexCount uint16
ScratchSpacePath string
}
func (s Indexes) WriteTo(w io.Writer) (int64, error) {
var currentOffset uint64 = HeaderSize
if len(s.Keys) > 0 {
currentOffset = uint64(s.Keys[len(s.Keys)-1].ValueEnd)
}
var written int64
if _, err := os.Stat(s.ScratchSpacePath); err == nil {
// exists, we need to delete
// This could be the case if Weaviate shut down unexpectedly (i.e. crashed)
// while a compaction was running. We can safely discard the contents of
// the scratch space.
if err := os.RemoveAll(s.ScratchSpacePath); err != nil {
return written, errors.Wrap(err, "clean up previous scratch space")
}
} else if os.IsNotExist(err) {
// does not exist yet, nothing to - will be created in the next step
} else {
return written, errors.Wrap(err, "check for scratch space directory")
}
if err := os.Mkdir(s.ScratchSpacePath, 0o777); err != nil {
return written, errors.Wrap(err, "create scratch space")
}
primaryFileName := filepath.Join(s.ScratchSpacePath, "primary")
primaryFD, err := os.Create(primaryFileName)
if err != nil {
return written, err
}
primaryFDBuffered := bufio.NewWriter(primaryFD)
n, err := s.buildAndMarshalPrimary(primaryFDBuffered, s.Keys)
if err != nil {
return written, err
}
if err := primaryFDBuffered.Flush(); err != nil {
return written, err
}
primaryFD.Seek(0, io.SeekStart)
// pretend that primary index was already written, then also account for the
// additional offset pointers (one for each secondary index)
currentOffset = currentOffset + uint64(n) +
uint64(s.SecondaryIndexCount)*8
// secondaryIndicesBytes := bytes.NewBuffer(nil)
secondaryFileName := filepath.Join(s.ScratchSpacePath, "secondary")
secondaryFD, err := os.Create(secondaryFileName)
if err != nil {
return written, err
}
secondaryFDBuffered := bufio.NewWriter(secondaryFD)
if s.SecondaryIndexCount > 0 {
offsets := make([]uint64, s.SecondaryIndexCount)
for pos := range offsets {
n, err := s.buildAndMarshalSecondary(secondaryFDBuffered, pos, s.Keys)
if err != nil {
return written, err
} else {
written += int64(n)
}
offsets[pos] = currentOffset
currentOffset = offsets[pos] + uint64(n)
}
if err := binary.Write(w, binary.LittleEndian, &offsets); err != nil {
return written, err
}
written += int64(len(offsets)) * 8
}
if err := secondaryFDBuffered.Flush(); err != nil {
return written, err
}
secondaryFD.Seek(0, io.SeekStart)
if n, err := io.Copy(w, primaryFD); err != nil {
return written, err
} else {
written += int64(n)
}
if n, err := io.Copy(w, secondaryFD); err != nil {
return written, err
} else {
written += int64(n)
}
if err := primaryFD.Close(); err != nil {
return written, err
}
if err := secondaryFD.Close(); err != nil {
return written, err
}
if err := os.RemoveAll(s.ScratchSpacePath); err != nil {
return written, err
}
return written, nil
}
// pos indicates the position of a secondary index, assumes unsorted keys and
// sorts them
func (s *Indexes) buildAndMarshalSecondary(w io.Writer, pos int,
keys []Key,
) (int64, error) {
keyNodes := make([]Node, len(keys))
i := 0
for _, key := range keys {
if pos >= len(key.SecondaryKeys) {
// a secondary key is not guaranteed to be present. For example, a delete
// operation could pe performed using only the primary key
continue
}
keyNodes[i] = Node{
Key: key.SecondaryKeys[pos],
Start: uint64(key.ValueStart),
End: uint64(key.ValueEnd),
}
i++
}
keyNodes = keyNodes[:i]
sort.Slice(keyNodes, func(a, b int) bool {
return bytes.Compare(keyNodes[a].Key, keyNodes[b].Key) < 0
})
index := NewBalanced(keyNodes)
n, err := index.MarshalBinaryInto(w)
if err != nil {
return 0, err
}
return n, nil
}
// assumes sorted keys and does NOT sort them again
func (s *Indexes) buildAndMarshalPrimary(w io.Writer, keys []Key) (int64, error) {
keyNodes := make([]Node, len(keys))
for i, key := range keys {
keyNodes[i] = Node{
Key: key.Key,
Start: uint64(key.ValueStart),
End: uint64(key.ValueEnd),
}
}
index := NewBalanced(keyNodes)
n, err := index.MarshalBinaryInto(w)
if err != nil {
return -1, err
}
return n, nil
}