VictoriaMetrics/lib/mergeset/part_header.go
Aliaksandr Valialkin 42bba64aa7
lib/{mergeset,storage}: explicitly fsync the created part directory listing
Previously the created part directory listing was fsynced implicitly
when storing metadata.json file in it.

Also remove superflouous fsync for part directory listing,
which was called at blockStreamWriter.MustClose().
After that the metadata.json file is created, so an additional fsync
for the directory contents is needed.
2023-04-13 21:03:08 -07:00

135 lines
3.6 KiB
Go

package mergeset
import (
"encoding/hex"
"encoding/json"
"fmt"
"os"
"path/filepath"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
)
type partHeader struct {
// The number of items the part contains.
itemsCount uint64
// The number of blocks the part contains.
blocksCount uint64
// The first item in the part.
firstItem []byte
// The last item in the part.
lastItem []byte
}
type partHeaderJSON struct {
ItemsCount uint64
BlocksCount uint64
FirstItem hexString
LastItem hexString
}
type hexString []byte
func (hs hexString) MarshalJSON() ([]byte, error) {
h := hex.EncodeToString(hs)
b := make([]byte, 0, len(h)+2)
b = append(b, '"')
b = append(b, h...)
b = append(b, '"')
return b, nil
}
func (hs *hexString) UnmarshalJSON(data []byte) error {
if len(data) < 2 {
return fmt.Errorf("too small data string: got %q; must be at least 2 bytes", data)
}
if data[0] != '"' || data[len(data)-1] != '"' {
return fmt.Errorf("missing heading and/or tailing quotes in the data string %q", data)
}
data = data[1 : len(data)-1]
b, err := hex.DecodeString(string(data))
if err != nil {
return fmt.Errorf("cannot hex-decode %q: %w", data, err)
}
*hs = b
return nil
}
func (ph *partHeader) Reset() {
ph.itemsCount = 0
ph.blocksCount = 0
ph.firstItem = ph.firstItem[:0]
ph.lastItem = ph.lastItem[:0]
}
func (ph *partHeader) String() string {
return fmt.Sprintf("partHeader{itemsCount: %d, blocksCount: %d, firstItem: %X, lastItem: %X}",
ph.itemsCount, ph.blocksCount, ph.firstItem, ph.lastItem)
}
func (ph *partHeader) CopyFrom(src *partHeader) {
ph.itemsCount = src.itemsCount
ph.blocksCount = src.blocksCount
ph.firstItem = append(ph.firstItem[:0], src.firstItem...)
ph.lastItem = append(ph.lastItem[:0], src.lastItem...)
}
func (ph *partHeader) ReadMetadata(partPath string) error {
ph.Reset()
// Read ph fields from metadata.
metadataPath := filepath.Join(partPath, metadataFilename)
metadata, err := os.ReadFile(metadataPath)
if err != nil {
return fmt.Errorf("cannot read %q: %w", metadataPath, err)
}
var phj partHeaderJSON
if err := json.Unmarshal(metadata, &phj); err != nil {
return fmt.Errorf("cannot parse %q: %w", metadataPath, err)
}
if phj.ItemsCount <= 0 {
return fmt.Errorf("part %q cannot contain zero items", partPath)
}
ph.itemsCount = phj.ItemsCount
if phj.BlocksCount <= 0 {
return fmt.Errorf("part %q cannot contain zero blocks", partPath)
}
if phj.BlocksCount > phj.ItemsCount {
return fmt.Errorf("the number of blocks cannot exceed the number of items in the part %q; got blocksCount=%d, itemsCount=%d",
partPath, phj.BlocksCount, phj.ItemsCount)
}
ph.blocksCount = phj.BlocksCount
ph.firstItem = append(ph.firstItem[:0], phj.FirstItem...)
ph.lastItem = append(ph.lastItem[:0], phj.LastItem...)
return nil
}
func (ph *partHeader) WriteMetadata(partPath string) error {
phj := &partHeaderJSON{
ItemsCount: ph.itemsCount,
BlocksCount: ph.blocksCount,
FirstItem: append([]byte{}, ph.firstItem...),
LastItem: append([]byte{}, ph.lastItem...),
}
metadata, err := json.Marshal(&phj)
if err != nil {
logger.Panicf("BUG: cannot marshal partHeader metadata: %s", err)
}
metadataPath := filepath.Join(partPath, metadataFilename)
// There is no need in calling fs.WriteFileAtomically() here,
// since the file is created only once during part creatinng
// and the part directory is synced aftewards.
if err := fs.WriteFileAndSync(metadataPath, metadata); err != nil {
return fmt.Errorf("cannot create %q: %w", metadataPath, err)
}
return nil
}