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// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
// All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
package leveldb
import (
"fmt"
"io"
"os"
"sync"
"github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/journal"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/syndtr/goleveldb/leveldb/storage"
)
// ErrManifestCorrupted records manifest corruption. This error will be
// wrapped with errors.ErrCorrupted.
type ErrManifestCorrupted struct {
Field string
Reason string
}
func (e *ErrManifestCorrupted) Error() string {
return fmt.Sprintf("leveldb: manifest corrupted (field '%s'): %s", e.Field, e.Reason)
}
func newErrManifestCorrupted(fd storage.FileDesc, field, reason string) error {
return errors.NewErrCorrupted(fd, &ErrManifestCorrupted{field, reason})
}
// session represent a persistent database session.
type session struct {
// Need 64-bit alignment.
stNextFileNum int64 // current unused file number
stJournalNum int64 // current journal file number; need external synchronization
stPrevJournalNum int64 // prev journal file number; no longer used; for compatibility with older version of leveldb
stTempFileNum int64
stSeqNum uint64 // last mem compacted seq; need external synchronization
stor storage.Storage
storLock storage.Locker
o *cachedOptions
icmp *iComparer
tops *tOps
manifest *journal.Writer
manifestWriter storage.Writer
manifestFd storage.FileDesc
stCompPtrs []internalKey // compaction pointers; need external synchronization
stVersion *version // current version
vmu sync.Mutex
}
// Creates new initialized session instance.
func newSession(stor storage.Storage, o *opt.Options) (s *session, err error) {
if stor == nil {
return nil, os.ErrInvalid
}
storLock, err := stor.Lock()
if err != nil {
return
}
s = &session{
stor: stor,
storLock: storLock,
}
s.setOptions(o)
s.tops = newTableOps(s)
s.setVersion(newVersion(s))
s.log("log@legend F·NumFile S·FileSize N·Entry C·BadEntry B·BadBlock Ke·KeyError D·DroppedEntry L·Level Q·SeqNum T·TimeElapsed")
return
}
// Close session.
func (s *session) close() {
s.tops.close()
if s.manifest != nil {
s.manifest.Close()
}
if s.manifestWriter != nil {
s.manifestWriter.Close()
}
s.manifest = nil
s.manifestWriter = nil
s.setVersion(&version{s: s, closing: true})
}
// Release session lock.
func (s *session) release() {
s.storLock.Unlock()
}
// Create a new database session; need external synchronization.
func (s *session) create() error {
// create manifest
return s.newManifest(nil, nil)
}
// 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 fds, _ := s.stor.List(storage.TypeAll); len(fds) > 0 {
err = &errors.ErrCorrupted{Fd: storage.FileDesc{Type: storage.TypeManifest}, Err: &errors.ErrMissingFiles{}}
}
}
}()
fd, err := s.stor.GetMeta()
if err != nil {
return
}
reader, err := s.stor.Open(fd)
if err != nil {
return
}
defer reader.Close()
var (
// Options.
strict = s.o.GetStrict(opt.StrictManifest)
jr = journal.NewReader(reader, dropper{s, fd}, strict, true)
rec = &sessionRecord{}
staging = s.stVersion.newStaging()
)
for {
var r io.Reader
r, err = jr.Next()
if err != nil {
if err == io.EOF {
err = nil
break
}
return errors.SetFd(err, fd)
}
err = rec.decode(r)
if err == nil {
// save compact pointers
for _, r := range rec.compPtrs {
s.setCompPtr(r.level, internalKey(r.ikey))
}
// commit record to version staging
staging.commit(rec)
} else {
err = errors.SetFd(err, fd)
if strict || !errors.IsCorrupted(err) {
return
}
s.logf("manifest error: %v (skipped)", errors.SetFd(err, fd))
}
rec.resetCompPtrs()
rec.resetAddedTables()
rec.resetDeletedTables()
}
switch {
case !rec.has(recComparer):
return newErrManifestCorrupted(fd, "comparer", "missing")
case rec.comparer != s.icmp.uName():
return newErrManifestCorrupted(fd, "comparer", fmt.Sprintf("mismatch: want '%s', got '%s'", s.icmp.uName(), rec.comparer))
case !rec.has(recNextFileNum):
return newErrManifestCorrupted(fd, "next-file-num", "missing")
case !rec.has(recJournalNum):
return newErrManifestCorrupted(fd, "journal-file-num", "missing")
case !rec.has(recSeqNum):
return newErrManifestCorrupted(fd, "seq-num", "missing")
}
s.manifestFd = fd
s.setVersion(staging.finish())
s.setNextFileNum(rec.nextFileNum)
s.recordCommited(rec)
return nil
}
// Commit session; need external synchronization.
func (s *session) commit(r *sessionRecord) (err error) {
v := s.version()
defer v.release()
// spawn new version based on current version
nv := v.spawn(r)
if s.manifest == nil {
// manifest journal writer not yet created, create one
err = s.newManifest(r, nv)
} else {
err = s.flushManifest(r)
}
// finally, apply new version if no error rise
if err == nil {
s.setVersion(nv)
}
return
}
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