/
leveldb.go
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/
leveldb.go
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// Copyright 2015 Keybase, Inc. All rights reserved. Use of
// this source code is governed by the included BSD license.
package libkb
import (
"fmt"
"os"
"strings"
"sync"
"github.com/syndtr/goleveldb/leveldb"
errors "github.com/syndtr/goleveldb/leveldb/errors"
"github.com/syndtr/goleveldb/leveldb/filter"
"github.com/syndtr/goleveldb/leveldb/opt"
)
// table names
const (
levelDbTableLo = "lo"
levelDbTableKv = "kv"
)
type levelDBOps interface {
Delete(key []byte, wo *opt.WriteOptions) error
Get(key []byte, ro *opt.ReadOptions) (value []byte, err error)
Put(key, value []byte, wo *opt.WriteOptions) error
Write(b *leveldb.Batch, wo *opt.WriteOptions) error
}
func levelDbPut(ops levelDBOps, id DbKey, aliases []DbKey, value []byte) (err error) {
defer convertNoSpaceError(err)
idb := id.ToBytes(levelDbTableKv)
if len(aliases) == 0 {
// if no aliases, just do a put
return ops.Put(idb, value, nil)
}
batch := new(leveldb.Batch)
batch.Put(idb, value)
if aliases != nil {
for _, alias := range aliases {
batch.Put(alias.ToBytes(levelDbTableLo), idb)
}
}
return ops.Write(batch, nil)
}
func levelDbGetWhich(ops levelDBOps, id DbKey, which string) (val []byte, found bool, err error) {
val, err = ops.Get(id.ToBytes(which), nil)
found = false
if err == nil {
found = true
} else if err == leveldb.ErrNotFound {
err = nil
}
return val, found, err
}
func levelDbGet(ops levelDBOps, id DbKey) (val []byte, found bool, err error) {
return levelDbGetWhich(ops, id, levelDbTableKv)
}
func levelDbLookup(ops levelDBOps, id DbKey) (val []byte, found bool, err error) {
val, found, err = levelDbGetWhich(ops, id, levelDbTableLo)
if found {
if tab, id2, err2 := DbKeyParse(string(val)); err2 != nil {
err = err2
} else if tab != levelDbTableKv {
err = fmt.Errorf("bad alias; expected 'kv' but got '%s'", tab)
} else {
val, found, err = levelDbGetWhich(ops, id2, levelDbTableKv)
}
}
return val, found, err
}
func levelDbDelete(ops levelDBOps, id DbKey) (err error) {
defer convertNoSpaceError(err)
return ops.Delete(id.ToBytes(levelDbTableKv), nil)
}
type LevelDb struct {
// We use a RWMutex here to ensure close doesn't happen in the middle of
// other DB operations, and DB operations doesn't happen after close. The
// lock should be considered for the db pointer and dbOpenerOnce pointer,
// rather than the DB itself. More specifically, close does Lock(), while
// other DB operations does RLock().
sync.RWMutex
db *leveldb.DB
dbOpenerOnce *sync.Once
filename string
Contextified
}
func NewLevelDb(g *GlobalContext, filename func() string) *LevelDb {
return &LevelDb{
Contextified: NewContextified(g),
filename: filename(),
dbOpenerOnce: new(sync.Once),
}
}
// Explicit open does nothing we'll wait for a lazy open
func (l *LevelDb) Open() error { return nil }
// Opts returns the options for all leveldb databases.
//
// PC: I think it's worth trying a bloom filter. From docs:
// "In many cases, a filter can cut down the number of disk
// seeks from a handful to a single disk seek per DB.Get call."
func (l *LevelDb) Opts() *opt.Options {
return &opt.Options{
OpenFilesCacheCapacity: l.G().Env.GetLevelDBNumFiles(),
Filter: filter.NewBloomFilter(10),
}
}
func (l *LevelDb) doWhileOpenAndNukeIfCorrupted(action func() error) (err error) {
err = func() error {
l.RLock()
defer l.RUnlock()
// This only happens at first ever doWhileOpenAndNukeIfCorrupted call, or
// when doOpenerOnce is just reset in Nuke()
l.dbOpenerOnce.Do(func() {
l.G().Log.Debug("+ LevelDb.open")
fn := l.GetFilename()
l.G().Log.Debug("| Opening LevelDB for local cache: %v %s", l, fn)
l.G().Log.Debug("| Opening LevelDB options: %+v", l.Opts())
l.db, err = leveldb.OpenFile(fn, l.Opts())
if err != nil {
if _, ok := err.(*errors.ErrCorrupted); ok {
l.G().Log.Debug("| LevelDb was corrupted; attempting recovery (%v)", err)
l.db, err = leveldb.RecoverFile(fn, nil)
if err != nil {
l.G().Log.Debug("| Recovery failed: %v", err)
} else {
l.G().Log.Debug("| Recovery succeeded!")
}
}
}
l.G().Log.Debug("- LevelDb.open -> %s", ErrToOk(err))
})
if err != nil {
return err
}
if l.db == nil {
// This means DB is already closed. We are preventing lazy-opening after
// closing, so just return error here.
return LevelDBOpenClosedError{}
}
return action()
}()
// If the file is corrupt, just nuke and act like we didn't find anything
if l.nukeIfCorrupt(err) {
err = nil
}
// Notably missing here is the error handling for when DB open fails but on
// an error other than "db is corrupted". We simply return the error here
// without resetting `dbOpenerOcce` (i.e. next call into LevelDb would result
// in a LevelDBOpenClosedError), because if DB open fails, retrying it
// wouldn't help. We should find the root cause and deal with it.
// MM: 10/12/2017: I am changing the above policy. I am not so sure retrying it won't help,
// we should at least try instead of auto returning LevelDBOpenClosederror.
if err != nil {
l.Lock()
if l.db == nil {
l.G().Log.Debug("LevelDb: doWhileOpenAndNukeIfCorrupted: resetting sync one: %s", err)
l.dbOpenerOnce = new(sync.Once)
}
l.Unlock()
}
return err
}
// ForceOpen opens the leveldb file. This is used in situations
// where we want to get around the lazy open and make sure we can
// use it later.
func (l *LevelDb) ForceOpen() error {
return l.doWhileOpenAndNukeIfCorrupted(func() error { return nil })
}
func (l *LevelDb) GetFilename() string {
if len(l.filename) == 0 {
l.G().Log.Fatalf("DB filename empty")
}
return l.filename
}
func (l *LevelDb) Close() error {
l.Lock()
defer l.Unlock()
return l.closeLocked()
}
func (l *LevelDb) closeLocked() error {
var err error
if l.db != nil {
l.G().Log.Debug("Closing LevelDB local cache: %s", l.GetFilename())
err = l.db.Close()
l.db = nil
// In case we just nuked DB and reset the dbOpenerOnce, this makes sure it
// doesn't open the DB again.
l.dbOpenerOnce.Do(func() {})
}
return err
}
func (l *LevelDb) isCorrupt(err error) bool {
if err == nil {
return false
}
// If the error is of type ErrCorrupted, then we nuke
if _, ok := err.(*errors.ErrCorrupted); ok {
return true
}
// Sometimes the LevelDB library will return generic error messages about
// corruption, also nuke on them
if strings.Contains(err.Error(), "corrupt") {
return true
}
return false
}
func (l *LevelDb) Nuke() (fn string, err error) {
l.Lock()
// We need to do deferred Unlock here in Nuke rather than delegating to
// l.Close() because we'll be re-opening the database later, and it's
// necesary to block other doWhileOpenAndNukeIfCorrupted() calls.
defer l.Unlock()
defer l.G().Trace("LevelDb::Nuke", func() error { return err })()
err = l.closeLocked()
if err != nil {
return "", err
}
fn = l.GetFilename()
err = os.RemoveAll(fn)
if err != nil {
return fn, err
}
// reset dbOpenerOnce since this is not a explicit close and there might be
// more legitimate DB operations coming in
l.dbOpenerOnce = new(sync.Once)
return fn, err
}
func (l *LevelDb) nukeIfCorrupt(err error) bool {
if l.isCorrupt(err) {
l.G().Log.Debug("LevelDB file corrupted, nuking database and starting fresh")
if _, err := l.Nuke(); err != nil {
l.G().Log.Debug("Error nuking LevelDB file: %s", err)
return false
}
return true
}
return false
}
func (l *LevelDb) Put(id DbKey, aliases []DbKey, value []byte) error {
return l.doWhileOpenAndNukeIfCorrupted(func() error {
return levelDbPut(l.db, id, aliases, value)
})
}
func (l *LevelDb) Get(id DbKey) (val []byte, found bool, err error) {
err = l.doWhileOpenAndNukeIfCorrupted(func() error {
val, found, err = levelDbGet(l.db, id)
return err
})
return val, found, err
}
func (l *LevelDb) Lookup(id DbKey) (val []byte, found bool, err error) {
err = l.doWhileOpenAndNukeIfCorrupted(func() error {
val, found, err = levelDbLookup(l.db, id)
return err
})
return val, found, err
}
func (l *LevelDb) Delete(id DbKey) error {
err := l.doWhileOpenAndNukeIfCorrupted(func() error {
return levelDbDelete(l.db, id)
})
return err
}
func (l *LevelDb) OpenTransaction() (LocalDbTransaction, error) {
var (
ltr LevelDbTransaction
err error
)
if ltr.tr, err = l.db.OpenTransaction(); err != nil {
return LevelDbTransaction{}, err
}
return ltr, nil
}
type LevelDbTransaction struct {
tr *leveldb.Transaction
}
func (l LevelDbTransaction) Put(id DbKey, aliases []DbKey, value []byte) error {
return levelDbPut(l.tr, id, aliases, value)
}
func (l LevelDbTransaction) Get(id DbKey) (val []byte, found bool, err error) {
return levelDbGet(l.tr, id)
}
func (l LevelDbTransaction) Lookup(id DbKey) (val []byte, found bool, err error) {
return levelDbLookup(l.tr, id)
}
func (l LevelDbTransaction) Delete(id DbKey) error {
return levelDbDelete(l.tr, id)
}
func (l LevelDbTransaction) Commit() (err error) {
defer convertNoSpaceError(err)
return l.tr.Commit()
}
func (l LevelDbTransaction) Discard() {
l.tr.Discard()
}
func convertNoSpaceError(err error) error {
if IsNoSpaceOnDeviceError(err) {
// embed in exportable error type
err = NoSpaceOnDeviceError{Desc: err.Error()}
}
return err
}