mirror of
https://github.com/go-gitea/gitea.git
synced 2024-08-30 16:17:28 +02:00
361 lines
6.8 KiB
Go
361 lines
6.8 KiB
Go
// Copyright (c) 2012, Suryandaru Triandana <syndtr@gmail.com>
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// All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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package leveldb
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import (
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"errors"
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"math/rand"
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"runtime"
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"sync"
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"sync/atomic"
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"github.com/syndtr/goleveldb/leveldb/iterator"
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"github.com/syndtr/goleveldb/leveldb/opt"
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"github.com/syndtr/goleveldb/leveldb/util"
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)
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var (
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errInvalidInternalKey = errors.New("leveldb: Iterator: invalid internal key")
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)
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type memdbReleaser struct {
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once sync.Once
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m *memDB
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}
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func (mr *memdbReleaser) Release() {
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mr.once.Do(func() {
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mr.m.decref()
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})
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}
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func (db *DB) newRawIterator(auxm *memDB, auxt tFiles, slice *util.Range, ro *opt.ReadOptions) iterator.Iterator {
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strict := opt.GetStrict(db.s.o.Options, ro, opt.StrictReader)
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em, fm := db.getMems()
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v := db.s.version()
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tableIts := v.getIterators(slice, ro)
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n := len(tableIts) + len(auxt) + 3
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its := make([]iterator.Iterator, 0, n)
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if auxm != nil {
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ami := auxm.NewIterator(slice)
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ami.SetReleaser(&memdbReleaser{m: auxm})
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its = append(its, ami)
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}
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for _, t := range auxt {
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its = append(its, v.s.tops.newIterator(t, slice, ro))
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}
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emi := em.NewIterator(slice)
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emi.SetReleaser(&memdbReleaser{m: em})
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its = append(its, emi)
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if fm != nil {
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fmi := fm.NewIterator(slice)
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fmi.SetReleaser(&memdbReleaser{m: fm})
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its = append(its, fmi)
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}
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its = append(its, tableIts...)
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mi := iterator.NewMergedIterator(its, db.s.icmp, strict)
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mi.SetReleaser(&versionReleaser{v: v})
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return mi
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}
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func (db *DB) newIterator(auxm *memDB, auxt tFiles, seq uint64, slice *util.Range, ro *opt.ReadOptions) *dbIter {
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var islice *util.Range
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if slice != nil {
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islice = &util.Range{}
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if slice.Start != nil {
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islice.Start = makeInternalKey(nil, slice.Start, keyMaxSeq, keyTypeSeek)
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}
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if slice.Limit != nil {
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islice.Limit = makeInternalKey(nil, slice.Limit, keyMaxSeq, keyTypeSeek)
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}
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}
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rawIter := db.newRawIterator(auxm, auxt, islice, ro)
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iter := &dbIter{
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db: db,
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icmp: db.s.icmp,
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iter: rawIter,
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seq: seq,
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strict: opt.GetStrict(db.s.o.Options, ro, opt.StrictReader),
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key: make([]byte, 0),
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value: make([]byte, 0),
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}
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atomic.AddInt32(&db.aliveIters, 1)
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runtime.SetFinalizer(iter, (*dbIter).Release)
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return iter
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}
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func (db *DB) iterSamplingRate() int {
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return rand.Intn(2 * db.s.o.GetIteratorSamplingRate())
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}
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type dir int
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const (
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dirReleased dir = iota - 1
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dirSOI
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dirEOI
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dirBackward
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dirForward
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)
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// dbIter represent an interator states over a database session.
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type dbIter struct {
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db *DB
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icmp *iComparer
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iter iterator.Iterator
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seq uint64
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strict bool
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smaplingGap int
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dir dir
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key []byte
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value []byte
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err error
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releaser util.Releaser
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}
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func (i *dbIter) sampleSeek() {
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ikey := i.iter.Key()
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i.smaplingGap -= len(ikey) + len(i.iter.Value())
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for i.smaplingGap < 0 {
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i.smaplingGap += i.db.iterSamplingRate()
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i.db.sampleSeek(ikey)
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}
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}
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func (i *dbIter) setErr(err error) {
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i.err = err
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i.key = nil
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i.value = nil
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}
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func (i *dbIter) iterErr() {
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if err := i.iter.Error(); err != nil {
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i.setErr(err)
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}
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}
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func (i *dbIter) Valid() bool {
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return i.err == nil && i.dir > dirEOI
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}
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func (i *dbIter) First() bool {
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if i.err != nil {
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return false
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} else if i.dir == dirReleased {
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i.err = ErrIterReleased
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return false
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}
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if i.iter.First() {
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i.dir = dirSOI
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return i.next()
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}
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i.dir = dirEOI
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i.iterErr()
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return false
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}
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func (i *dbIter) Last() bool {
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if i.err != nil {
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return false
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} else if i.dir == dirReleased {
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i.err = ErrIterReleased
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return false
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}
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if i.iter.Last() {
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return i.prev()
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}
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i.dir = dirSOI
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i.iterErr()
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return false
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}
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func (i *dbIter) Seek(key []byte) bool {
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if i.err != nil {
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return false
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} else if i.dir == dirReleased {
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i.err = ErrIterReleased
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return false
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}
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ikey := makeInternalKey(nil, key, i.seq, keyTypeSeek)
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if i.iter.Seek(ikey) {
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i.dir = dirSOI
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return i.next()
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}
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i.dir = dirEOI
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i.iterErr()
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return false
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}
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func (i *dbIter) next() bool {
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for {
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if ukey, seq, kt, kerr := parseInternalKey(i.iter.Key()); kerr == nil {
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i.sampleSeek()
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if seq <= i.seq {
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switch kt {
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case keyTypeDel:
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// Skip deleted key.
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i.key = append(i.key[:0], ukey...)
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i.dir = dirForward
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case keyTypeVal:
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if i.dir == dirSOI || i.icmp.uCompare(ukey, i.key) > 0 {
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i.key = append(i.key[:0], ukey...)
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i.value = append(i.value[:0], i.iter.Value()...)
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i.dir = dirForward
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return true
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}
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}
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}
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} else if i.strict {
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i.setErr(kerr)
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break
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}
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if !i.iter.Next() {
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i.dir = dirEOI
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i.iterErr()
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break
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}
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}
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return false
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}
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func (i *dbIter) Next() bool {
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if i.dir == dirEOI || i.err != nil {
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return false
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} else if i.dir == dirReleased {
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i.err = ErrIterReleased
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return false
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}
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if !i.iter.Next() || (i.dir == dirBackward && !i.iter.Next()) {
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i.dir = dirEOI
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i.iterErr()
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return false
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}
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return i.next()
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}
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func (i *dbIter) prev() bool {
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i.dir = dirBackward
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del := true
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if i.iter.Valid() {
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for {
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if ukey, seq, kt, kerr := parseInternalKey(i.iter.Key()); kerr == nil {
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i.sampleSeek()
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if seq <= i.seq {
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if !del && i.icmp.uCompare(ukey, i.key) < 0 {
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return true
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}
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del = (kt == keyTypeDel)
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if !del {
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i.key = append(i.key[:0], ukey...)
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i.value = append(i.value[:0], i.iter.Value()...)
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}
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}
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} else if i.strict {
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i.setErr(kerr)
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return false
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}
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if !i.iter.Prev() {
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break
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}
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}
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}
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if del {
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i.dir = dirSOI
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i.iterErr()
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return false
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}
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return true
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}
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func (i *dbIter) Prev() bool {
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if i.dir == dirSOI || i.err != nil {
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return false
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} else if i.dir == dirReleased {
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i.err = ErrIterReleased
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return false
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}
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switch i.dir {
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case dirEOI:
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return i.Last()
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case dirForward:
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for i.iter.Prev() {
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if ukey, _, _, kerr := parseInternalKey(i.iter.Key()); kerr == nil {
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i.sampleSeek()
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if i.icmp.uCompare(ukey, i.key) < 0 {
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goto cont
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}
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} else if i.strict {
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i.setErr(kerr)
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return false
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}
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}
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i.dir = dirSOI
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i.iterErr()
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return false
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}
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cont:
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return i.prev()
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}
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func (i *dbIter) Key() []byte {
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if i.err != nil || i.dir <= dirEOI {
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return nil
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}
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return i.key
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}
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func (i *dbIter) Value() []byte {
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if i.err != nil || i.dir <= dirEOI {
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return nil
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}
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return i.value
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}
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func (i *dbIter) Release() {
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if i.dir != dirReleased {
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// Clear the finalizer.
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runtime.SetFinalizer(i, nil)
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if i.releaser != nil {
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i.releaser.Release()
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i.releaser = nil
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}
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i.dir = dirReleased
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i.key = nil
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i.value = nil
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i.iter.Release()
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i.iter = nil
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atomic.AddInt32(&i.db.aliveIters, -1)
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i.db = nil
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}
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}
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func (i *dbIter) SetReleaser(releaser util.Releaser) {
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if i.dir == dirReleased {
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panic(util.ErrReleased)
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}
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if i.releaser != nil && releaser != nil {
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panic(util.ErrHasReleaser)
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}
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i.releaser = releaser
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}
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func (i *dbIter) Error() error {
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return i.err
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}
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