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251 lines
4.7 KiB
251 lines
4.7 KiB
package db
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import (
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"fmt"
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"sort"
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"sync"
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)
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func init() {
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registerDBCreator(MemDBBackend, func(name string, dir string) (DB, error) {
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return NewMemDB(), nil
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}, false)
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}
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var _ DB = (*MemDB)(nil)
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type MemDB struct {
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mtx sync.Mutex
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db map[string][]byte
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}
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func NewMemDB() *MemDB {
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database := &MemDB{
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db: make(map[string][]byte),
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}
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return database
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}
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// Implements atomicSetDeleter.
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func (db *MemDB) Mutex() *sync.Mutex {
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return &(db.mtx)
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}
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// Implements DB.
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func (db *MemDB) Get(key []byte) []byte {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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key = nonNilBytes(key)
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return db.db[string(key)]
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}
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// Implements DB.
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func (db *MemDB) Has(key []byte) bool {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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key = nonNilBytes(key)
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_, ok := db.db[string(key)]
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return ok
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}
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// Implements DB.
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func (db *MemDB) Set(key []byte, value []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.SetNoLock(key, value)
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}
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// Implements DB.
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func (db *MemDB) SetSync(key []byte, value []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.SetNoLock(key, value)
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}
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// Implements atomicSetDeleter.
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func (db *MemDB) SetNoLock(key []byte, value []byte) {
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db.SetNoLockSync(key, value)
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}
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// Implements atomicSetDeleter.
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func (db *MemDB) SetNoLockSync(key []byte, value []byte) {
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key = nonNilBytes(key)
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value = nonNilBytes(value)
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db.db[string(key)] = value
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}
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// Implements DB.
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func (db *MemDB) Delete(key []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.DeleteNoLock(key)
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}
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// Implements DB.
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func (db *MemDB) DeleteSync(key []byte) {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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db.DeleteNoLock(key)
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}
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// Implements atomicSetDeleter.
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func (db *MemDB) DeleteNoLock(key []byte) {
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db.DeleteNoLockSync(key)
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}
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// Implements atomicSetDeleter.
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func (db *MemDB) DeleteNoLockSync(key []byte) {
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key = nonNilBytes(key)
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delete(db.db, string(key))
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}
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// Implements DB.
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func (db *MemDB) Close() {
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// Close is a noop since for an in-memory
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// database, we don't have a destination
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// to flush contents to nor do we want
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// any data loss on invoking Close()
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// See the discussion in https://github.com/tendermint/tmlibs/pull/56
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}
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// Implements DB.
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func (db *MemDB) Print() {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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for key, value := range db.db {
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fmt.Printf("[%X]:\t[%X]\n", []byte(key), value)
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}
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}
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// Implements DB.
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func (db *MemDB) Stats() map[string]string {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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stats := make(map[string]string)
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stats["database.type"] = "memDB"
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stats["database.size"] = fmt.Sprintf("%d", len(db.db))
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return stats
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}
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// Implements DB.
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func (db *MemDB) NewBatch() Batch {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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return &memBatch{db, nil}
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}
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//----------------------------------------
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// Iterator
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// Implements DB.
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func (db *MemDB) Iterator(start, end []byte) Iterator {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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keys := db.getSortedKeys(start, end, false)
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return newMemDBIterator(db, keys, start, end)
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}
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// Implements DB.
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func (db *MemDB) ReverseIterator(start, end []byte) Iterator {
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db.mtx.Lock()
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defer db.mtx.Unlock()
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keys := db.getSortedKeys(end, start, true)
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return newMemDBIterator(db, keys, start, end)
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}
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// We need a copy of all of the keys.
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// Not the best, but probably not a bottleneck depending.
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type memDBIterator struct {
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db DB
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cur int
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keys []string
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start []byte
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end []byte
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}
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var _ Iterator = (*memDBIterator)(nil)
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// Keys is expected to be in reverse order for reverse iterators.
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func newMemDBIterator(db DB, keys []string, start, end []byte) *memDBIterator {
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return &memDBIterator{
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db: db,
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cur: 0,
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keys: keys,
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start: start,
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end: end,
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}
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}
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// Implements Iterator.
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func (itr *memDBIterator) Domain() ([]byte, []byte) {
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return itr.start, itr.end
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}
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// Implements Iterator.
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func (itr *memDBIterator) Valid() bool {
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return 0 <= itr.cur && itr.cur < len(itr.keys)
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}
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// Implements Iterator.
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func (itr *memDBIterator) Next() {
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itr.assertIsValid()
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itr.cur++
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}
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// Implements Iterator.
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func (itr *memDBIterator) Key() []byte {
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itr.assertIsValid()
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return []byte(itr.keys[itr.cur])
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}
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// Implements Iterator.
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func (itr *memDBIterator) Value() []byte {
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itr.assertIsValid()
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key := []byte(itr.keys[itr.cur])
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return itr.db.Get(key)
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}
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// Implements Iterator.
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func (itr *memDBIterator) Close() {
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itr.keys = nil
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itr.db = nil
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}
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func (itr *memDBIterator) assertIsValid() {
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if !itr.Valid() {
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panic("memDBIterator is invalid")
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}
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}
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//----------------------------------------
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// Misc.
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func (db *MemDB) getSortedKeys(start, end []byte, reverse bool) []string {
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keys := []string{}
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for key, _ := range db.db {
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if IsKeyInDomain([]byte(key), start, end, false) {
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keys = append(keys, key)
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}
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}
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sort.Strings(keys)
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if reverse {
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nkeys := len(keys)
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for i := 0; i < nkeys/2; i++ {
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keys[i] = keys[nkeys-i-1]
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}
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}
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return keys
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}
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