// Recover a database session; need external synchronization.
func (s *session) recover() (err error) {
defer func() {
if os.IsNotExist(err) {
// Don't return os.ErrNotExist if the underlying storage contains
// other files that belong to LevelDB. So the DB won't get trashed.
if files, _ := s.stor.GetFiles(storage.TypeAll); len(files) > 0 {
err = ErrCorrupted{Type: CorruptedManifest, Err: errors.New("leveldb: manifest file missing")}
}
}
}()
file, err := s.stor.GetManifest()
if err != nil {
return
}
reader, err := file.Open()
if err != nil {
return
}
defer reader.Close()
strict := s.o.GetStrict(opt.StrictManifest)
jr := journal.NewReader(reader, dropper{s, file}, strict, true)
staging := s.version_NB().newStaging()
rec := &sessionRecord{}
for {
var r io.Reader
r, err = jr.Next()
if err != nil {
if err == io.EOF {
err = nil
break
}
return
}
err = rec.decode(r)
if err == nil {
// save compact pointers
for _, r := range rec.compactionPointers {
s.stCptrs[r.level] = iKey(r.ikey)
}
// commit record to version staging
staging.commit(rec)
} else if strict {
return ErrCorrupted{Type: CorruptedManifest, Err: err}
} else {
s.logf("manifest error: %v (skipped)", err)
}
rec.resetCompactionPointers()
rec.resetAddedTables()
rec.resetDeletedTables()
}
switch {
case !rec.has(recComparer):
return ErrCorrupted{Type: CorruptedManifest, Err: errors.New("leveldb: manifest missing comparer name")}
case rec.comparer != s.icmp.uName():
return ErrCorrupted{Type: CorruptedManifest, Err: errors.New("leveldb: comparer mismatch, " + "want '" + s.icmp.uName() + "', " + "got '" + rec.comparer + "'")}
case !rec.has(recNextNum):
return ErrCorrupted{Type: CorruptedManifest, Err: errors.New("leveldb: manifest missing next file number")}
case !rec.has(recJournalNum):
return ErrCorrupted{Type: CorruptedManifest, Err: errors.New("leveldb: manifest missing journal file number")}
case !rec.has(recSeq):
return ErrCorrupted{Type: CorruptedManifest, Err: errors.New("leveldb: manifest missing seq number")}
}
s.manifestFile = file
s.setVersion(staging.finish())
s.setFileNum(rec.nextNum)
s.recordCommited(rec)
return nil
}
func (db *DB) recoverJournal() error {
// Get all tables and sort it by file number.
journalFiles_, err := db.s.getFiles(storage.TypeJournal)
if err != nil {
return err
}
journalFiles := files(journalFiles_)
journalFiles.sort()
// Discard older journal.
prev := -1
for i, file := range journalFiles {
if file.Num() >= db.s.stJournalNum {
if prev >= 0 {
i--
journalFiles[i] = journalFiles[prev]
}
journalFiles = journalFiles[i:]
break
} else if file.Num() == db.s.stPrevJournalNum {
prev = i
}
}
var jr *journal.Reader
var of storage.File
var mem *memdb.DB
batch := new(Batch)
cm := newCMem(db.s)
buf := new(util.Buffer)
// Options.
strict := db.s.o.GetStrict(opt.StrictJournal)
checksum := db.s.o.GetStrict(opt.StrictJournalChecksum)
writeBuffer := db.s.o.GetWriteBuffer()
recoverJournal := func(file storage.File) error {
db.logf("journal@recovery recovering @%d", file.Num())
reader, err := file.Open()
if err != nil {
return err
}
defer reader.Close()
// Create/reset journal reader instance.
if jr == nil {
jr = journal.NewReader(reader, dropper{db.s, file}, strict, checksum)
} else {
jr.Reset(reader, dropper{db.s, file}, strict, checksum)
}
// Flush memdb and remove obsolete journal file.
if of != nil {
if mem.Len() > 0 {
if err := cm.flush(mem, 0); err != nil {
return err
}
}
if err := cm.commit(file.Num(), db.seq); err != nil {
return err
}
cm.reset()
of.Remove()
of = nil
}
// Replay journal to memdb.
mem.Reset()
for {
r, err := jr.Next()
if err != nil {
if err == io.EOF {
break
}
return err
}
buf.Reset()
if _, err := buf.ReadFrom(r); err != nil {
if err == io.ErrUnexpectedEOF {
continue
} else {
return err
}
}
if err := batch.decode(buf.Bytes()); err != nil {
return err
}
if err := batch.memReplay(mem); err != nil {
return err
}
// Save sequence number.
db.seq = batch.seq + uint64(batch.len())
// Flush it if large enough.
if mem.Size() >= writeBuffer {
if err := cm.flush(mem, 0); err != nil {
return err
}
mem.Reset()
}
}
of = file
return nil
}
// Recover all journals.
if len(journalFiles) > 0 {
db.logf("journal@recovery F·%d", len(journalFiles))
// Mark file number as used.
db.s.markFileNum(journalFiles[len(journalFiles)-1].Num())
mem = memdb.New(db.s.icmp, writeBuffer)
for _, file := range journalFiles {
if err := recoverJournal(file); err != nil {
return err
}
}
// Flush the last journal.
if mem.Len() > 0 {
if err := cm.flush(mem, 0); err != nil {
return err
}
}
}
// Create a new journal.
if _, err := db.newMem(0); err != nil {
return err
}
// Commit.
if err := cm.commit(db.journalFile.Num(), db.seq); err != nil {
// Close journal.
if db.journal != nil {
db.journal.Close()
db.journalWriter.Close()
}
return err
}
// Remove the last obsolete journal file.
if of != nil {
of.Remove()
}
return nil
}