VictoriaMetrics/lib/mergeset/part_header.go
hagen1778 1154f90d2d
lib/mergeset: fix typos in comments
Signed-off-by: hagen1778 <roman@victoriametrics.com>
2024-08-07 15:54:15 +02:00

131 lines
3.5 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) MustReadMetadata(partPath string) {
ph.Reset()
// Read ph fields from metadata.
metadataPath := filepath.Join(partPath, metadataFilename)
metadata, err := os.ReadFile(metadataPath)
if err != nil {
logger.Panicf("FATAL: cannot read %q: %s", metadataPath, err)
}
var phj partHeaderJSON
if err := json.Unmarshal(metadata, &phj); err != nil {
logger.Panicf("FATAL: cannot parse %q: %s", metadataPath, err)
}
if phj.ItemsCount <= 0 {
logger.Panicf("FATAL: part %q cannot contain zero items", partPath)
}
ph.itemsCount = phj.ItemsCount
if phj.BlocksCount <= 0 {
logger.Panicf("FATAL: part %q cannot contain zero blocks", partPath)
}
if phj.BlocksCount > phj.ItemsCount {
logger.Panicf("FATAL: 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...)
}
func (ph *partHeader) MustWriteMetadata(partPath string) {
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.MustWriteAtomic() here,
// since the file is created only once during part creation
// and the part directory is synced afterward.
fs.MustWriteSync(metadataPath, metadata)
}