VictoriaMetrics/lib/mergeset/part_header.go
Aliaksandr Valialkin e2de5bf763
lib/{storage,mergeset}: convert InitFromFilePart to MustInitFromFilePart
Callers of InitFromFilePart log the error and exit.
It is better to log the error with the path to the part and the call stack
directly inside the MustInitFromFilePart() function.
This simplifies the code at callers' side while leaving the same level of debuggability.
2023-04-14 15:47:20 -07:00

130 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 creatinng
// and the part directory is synced aftewards.
fs.MustWriteSync(metadataPath, metadata)
}