func (t *tOps) lookup(f *tFile) (c cache.Object, err error) {
num := f.file.Num()
c, ok := t.cacheNS.Get(num, func() (ok bool, value interface{}, charge int, fin cache.SetFin) {
var r storage.Reader
r, err = f.file.Open()
if err != nil {
return
}
o := t.s.o
var cacheNS cache.Namespace
if bc := o.GetBlockCache(); bc != nil {
cacheNS = bc.GetNamespace(num)
}
ok = true
value = table.NewReader(r, int64(f.size), cacheNS, o)
charge = 1
fin = func() {
r.Close()
}
return
})
if !ok && err == nil {
err = ErrClosed
}
return
}
// Recover recovers and opens a DB with missing or corrupted manifest files
// for the given storage. It will ignore any manifest files, valid or not.
// The DB must already exist or it will returns an error.
// Also, Recover will ignore ErrorIfMissing and ErrorIfExist options.
//
// The DB must be closed after use, by calling Close method.
func Recover(p storage.Storage, o *opt.Options) (db *DB, err error) {
s, err := newSession(p, o)
if err != nil {
return
}
defer func() {
if err != nil {
s.close()
s.release()
}
}()
// get all files
ff0, err := s.getFiles(storage.TypeAll)
if err != nil {
return
}
ff := files(ff0)
ff.sort()
s.logf("db@recovery F·%d", len(ff))
rec := new(sessionRecord)
// recover tables
var nt *tFile
for _, f := range ff {
if f.Type() != storage.TypeTable {
continue
}
var r storage.Reader
r, err = f.Open()
if err != nil {
return
}
var size int64
size, err = r.Seek(0, 2)
r.Close()
if err != nil {
return
}
t := newTFile(f, uint64(size), nil, nil)
iter := s.tops.newIterator(t, nil, nil)
// min ikey
if iter.First() {
t.min = iter.Key()
} else {
err = iter.Error()
iter.Release()
if err != nil {
return
} else {
continue
}
}
// max ikey
if iter.Last() {
t.max = iter.Key()
} else {
err = iter.Error()
iter.Release()
if err != nil {
return
} else {
continue
}
}
iter.Release()
s.logf("db@recovery found table @%d S·%s %q:%q", t.file.Num(), shortenb(int(t.size)), t.min, t.max)
// add table to level 0
rec.addTableFile(0, t)
nt = t
}
// extract largest seq number from newest table
if nt != nil {
var lseq uint64
iter := s.tops.newIterator(nt, nil, nil)
for iter.Next() {
seq, _, ok := iKey(iter.Key()).parseNum()
if !ok {
continue
}
if seq > lseq {
lseq = seq
}
}
iter.Release()
rec.setSeq(lseq)
}
// set file num based on largest one
if len(ff) > 0 {
s.stFileNum = ff[len(ff)-1].Num() + 1
} else {
s.stFileNum = 0
}
// create brand new manifest
err = s.create()
if err != nil {
return
}
// commit record
err = s.commit(rec)
if err != nil {
return
}
return openDB(s)
}