func BenchmarkDBReadReverse(b *testing.B) {
p := openDBBench(b)
p.populate(b.N)
p.fill()
p.drop()
iter := p.newIter()
b.ResetTimer()
iter.Last()
for iter.Prev() {
}
b.StopTimer()
b.SetBytes(116)
p.close()
}
// Recover recover database with missing or corrupted manifest file. It will
// ignore any manifest files, valid or not.
func Recover(d desc.Desc, o *opt.Options) (db *DB, err error) {
s := newSession(d, o)
// get all files
ff := files(s.getFiles(desc.TypeAll))
ff.sort()
s.printf("Recover: started, files=%d", len(ff))
rec := new(sessionRecord)
// recover tables
ro := &opt.ReadOptions{}
var nt *tFile
for _, f := range ff {
if f.Type() != desc.TypeTable {
continue
}
var size uint64
size, err = f.Size()
if err != nil {
return
}
t := newTFile(f, size, nil, nil)
iter := s.tops.newIterator(t, ro)
// min ikey
if iter.First() {
t.min = iter.Key()
} else if iter.Error() != nil {
err = iter.Error()
return
} else {
continue
}
// max ikey
if iter.Last() {
t.max = iter.Key()
} else if iter.Error() != nil {
err = iter.Error()
return
} else {
continue
}
// 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, ro)
for iter.Next() {
seq, _, ok := iKey(iter.Key()).parseNum()
if !ok {
continue
}
if seq > lseq {
lseq = seq
}
}
rec.setSeq(lseq)
}
// set file num based on largest one
s.stFileNum = ff[len(ff)-1].Num() + 1
// create brand new manifest
err = s.create()
if err != nil {
return
}
// commit record
err = s.commit(rec)
if err != nil {
return
}
return open(s)
}