You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
274 lines
6.5 KiB
Go
274 lines
6.5 KiB
Go
package snapshot
|
|
|
|
import (
|
|
"encoding/json"
|
|
"fmt"
|
|
"io"
|
|
"log"
|
|
"os"
|
|
"path/filepath"
|
|
"runtime"
|
|
"strings"
|
|
|
|
"github.com/rqlite/rqlite/db"
|
|
)
|
|
|
|
// Sink is a sink for writing snapshot data to a Snapshot store.
|
|
type Sink struct {
|
|
workDir string
|
|
curGenDir string
|
|
nextGenDir string
|
|
meta *Meta
|
|
|
|
dataFD *os.File
|
|
|
|
logger *log.Logger
|
|
closed bool
|
|
}
|
|
|
|
// NewSink creates a new Sink object.
|
|
func NewSink(workDir, currGenDir, nextGenDir string, meta *Meta) *Sink {
|
|
return &Sink{
|
|
workDir: workDir,
|
|
curGenDir: currGenDir,
|
|
nextGenDir: nextGenDir,
|
|
meta: meta,
|
|
logger: log.New(os.Stderr, "snapshot-sink: ", log.LstdFlags),
|
|
}
|
|
}
|
|
|
|
// Open opens the sink for writing.
|
|
func (s *Sink) Open() error {
|
|
dataPath := filepath.Join(s.workDir, "snapshot-data.tmp")
|
|
dataFD, err := os.Create(dataPath)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
s.dataFD = dataFD
|
|
return nil
|
|
}
|
|
|
|
// Write writes snapshot data to the sink. The snapshot is not in place
|
|
// until Close is called.
|
|
func (s *Sink) Write(p []byte) (n int, err error) {
|
|
return s.dataFD.Write(p)
|
|
}
|
|
|
|
// ID returns the ID of the snapshot being written.
|
|
func (s *Sink) ID() string {
|
|
return s.meta.ID
|
|
}
|
|
|
|
// Cancel cancels the snapshot.
|
|
func (s *Sink) Cancel() error {
|
|
s.closed = true
|
|
return s.cleanup()
|
|
}
|
|
|
|
// Close closes the sink, and finalizes creation of the snapshot.
|
|
func (s *Sink) Close() error {
|
|
if s.closed {
|
|
return nil
|
|
}
|
|
s.closed = true
|
|
defer s.cleanup()
|
|
return s.processSnapshotData()
|
|
}
|
|
|
|
func (s *Sink) processSnapshotData() error {
|
|
if _, err := s.dataFD.Seek(0, 0); err != nil {
|
|
return err
|
|
}
|
|
|
|
strHdr, _, err := NewStreamHeaderFromReader(s.dataFD)
|
|
if err != nil {
|
|
return fmt.Errorf("error reading stream header: %v", err)
|
|
}
|
|
if strHdr.GetVersion() != streamVersion {
|
|
return fmt.Errorf("unsupported snapshot version %d", strHdr.GetVersion())
|
|
}
|
|
|
|
if incSnap := strHdr.GetIncrementalSnapshot(); incSnap != nil {
|
|
return s.processIncrementalSnapshot(incSnap)
|
|
}
|
|
fullSnap := strHdr.GetFullSnapshot()
|
|
if fullSnap == nil {
|
|
return fmt.Errorf("got nil FullSnapshot")
|
|
}
|
|
return s.processFullSnapshot(fullSnap)
|
|
}
|
|
|
|
func (s *Sink) processIncrementalSnapshot(incSnap *IncrementalSnapshot) error {
|
|
s.logger.Printf("processing incremental snapshot")
|
|
|
|
incSnapDir := tmpName(filepath.Join(s.curGenDir, s.meta.ID))
|
|
walPath := filepath.Join(incSnapDir, snapWALFile)
|
|
if err := os.WriteFile(walPath, incSnap.Data, 0644); err != nil {
|
|
return fmt.Errorf("error writing WAL data: %v", err)
|
|
}
|
|
if err := s.writeMeta(incSnapDir, false); err != nil {
|
|
return err
|
|
}
|
|
|
|
// We're done! Move the directory into place.
|
|
dstDir, err := moveFromTmpSync(incSnapDir)
|
|
if err != nil {
|
|
s.logger.Printf("failed to move incremental snapshot directory into place: %s", err)
|
|
return err
|
|
}
|
|
s.logger.Printf("incremental snapshot (ID %s) written to %s", s.meta.ID, dstDir)
|
|
return nil
|
|
}
|
|
|
|
func (s *Sink) processFullSnapshot(fullSnap *FullSnapshot) error {
|
|
s.logger.Printf("processing full snapshot")
|
|
|
|
// We need a new generational directory, and need to create the first
|
|
// snapshot in that directory.
|
|
nextGenDir := tmpName(s.nextGenDir)
|
|
if err := os.MkdirAll(nextGenDir, 0755); err != nil {
|
|
return fmt.Errorf("error creating full snapshot directory: %v", err)
|
|
}
|
|
|
|
// Write out base SQLite file.
|
|
sqliteBasePath := filepath.Join(nextGenDir, baseSqliteFile)
|
|
dbInfo := fullSnap.GetDb()
|
|
if dbInfo == nil {
|
|
return fmt.Errorf("got nil DB info")
|
|
}
|
|
sqliteBaseFD, err := os.Create(sqliteBasePath)
|
|
if err != nil {
|
|
return fmt.Errorf("error creating SQLite file: %v", err)
|
|
}
|
|
if _, err := io.CopyN(sqliteBaseFD, s.dataFD, dbInfo.Size); err != nil {
|
|
return fmt.Errorf("error writing SQLite file data: %v", err)
|
|
}
|
|
if err := sqliteBaseFD.Close(); err != nil {
|
|
return fmt.Errorf("error closing SQLite file: %v", err)
|
|
}
|
|
|
|
// Write out any WALs.
|
|
var walFiles []string
|
|
for i, wal := range fullSnap.GetWals() {
|
|
if wal == nil {
|
|
return fmt.Errorf("got nil WAL")
|
|
}
|
|
|
|
walName := filepath.Join(nextGenDir, baseSqliteWALFile+fmt.Sprintf("%d", i))
|
|
walFD, err := os.Create(walName)
|
|
if err != nil {
|
|
return fmt.Errorf("error creating WAL file: %v", err)
|
|
}
|
|
if _, err := io.CopyN(walFD, s.dataFD, wal.Size); err != nil {
|
|
return fmt.Errorf("error writing WAL file data: %v", err)
|
|
}
|
|
if err := walFD.Close(); err != nil {
|
|
return fmt.Errorf("error closing WAL file: %v", err)
|
|
}
|
|
walFiles = append(walFiles, walName)
|
|
}
|
|
|
|
// Checkpoint the WAL files into the base SQLite file
|
|
if err := db.ReplayWAL(sqliteBasePath, walFiles, false); err != nil {
|
|
return fmt.Errorf("error checkpointing WAL: %v", err)
|
|
}
|
|
|
|
// Now create the first snapshot directory in the new generation.
|
|
snapDir := filepath.Join(nextGenDir, s.meta.ID)
|
|
if err := os.MkdirAll(snapDir, 0755); err != nil {
|
|
return fmt.Errorf("error creating full snapshot directory: %v", err)
|
|
}
|
|
if err := s.writeMeta(snapDir, true); err != nil {
|
|
return err
|
|
}
|
|
|
|
// We're done! Move the directory into place.
|
|
dstDir, err := moveFromTmpSync(nextGenDir)
|
|
if err != nil {
|
|
s.logger.Printf("failed to move full snapshot directory into place: %s", err)
|
|
return err
|
|
}
|
|
s.logger.Printf("full snapshot (ID %s) written to %s", s.meta.ID, dstDir)
|
|
return nil
|
|
}
|
|
|
|
func (s *Sink) writeMeta(dir string, full bool) error {
|
|
fh, err := os.Create(filepath.Join(dir, metaFileName))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer fh.Close()
|
|
s.meta.Full = full
|
|
|
|
// Write out as JSON
|
|
enc := json.NewEncoder(fh)
|
|
if err = enc.Encode(s.meta); err != nil {
|
|
return err
|
|
}
|
|
|
|
if err := fh.Sync(); err != nil {
|
|
return err
|
|
}
|
|
return fh.Close()
|
|
}
|
|
|
|
func (s *Sink) cleanup() error {
|
|
if s.dataFD != nil {
|
|
if err := s.dataFD.Close(); err != nil {
|
|
return err
|
|
}
|
|
if err := os.Remove(s.dataFD.Name()); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
|
|
if err := os.RemoveAll(tmpName(s.nextGenDir)); err != nil {
|
|
return err
|
|
}
|
|
if err := os.RemoveAll(tmpName(s.curGenDir)); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func parentDir(dir string) string {
|
|
return filepath.Dir(dir)
|
|
}
|
|
|
|
func tmpName(path string) string {
|
|
return path + tmpSuffix
|
|
}
|
|
|
|
func nonTmpName(path string) string {
|
|
return strings.TrimSuffix(path, tmpSuffix)
|
|
}
|
|
|
|
func moveFromTmpSync(src string) (string, error) {
|
|
dst := nonTmpName(src)
|
|
if err := os.Rename(src, dst); err != nil {
|
|
return "", err
|
|
}
|
|
|
|
// Sync parent directory to ensure snapshot is visible, but it's only
|
|
// needed on *nix style file systems.
|
|
if runtime.GOOS != "windows" {
|
|
if err := syncDir(parentDir(dst)); err != nil {
|
|
return "", err
|
|
}
|
|
}
|
|
return dst, nil
|
|
}
|
|
|
|
func syncDir(dir string) error {
|
|
fh, err := os.Open(dir)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer fh.Close()
|
|
|
|
if err := fh.Sync(); err != nil {
|
|
return err
|
|
}
|
|
return fh.Close()
|
|
}
|