698a25b8e2
When a key is deleted in a for loop, calling cursor.next() jumps a key. As a result we must seek to the prefix again, until all keys with the prefix are deleted.
363 lines
6.3 KiB
Go
363 lines
6.3 KiB
Go
// Copyright © 2016 Abcum Ltd
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package kvs
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import (
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"bytes"
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"math"
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"github.com/boltdb/bolt"
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"github.com/abcum/surreal/util/cryp"
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"github.com/abcum/surreal/util/snap"
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)
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// TX is a distributed database transaction.
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type TX struct {
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db *DB
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ck []byte
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tx *bolt.Tx
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bu *bolt.Bucket
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}
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// All retrieves all key:value items in the db.
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func (tx *TX) All() (kvs []*KV, err error) {
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err = tx.bu.ForEach(func(key, val []byte) (err error) {
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kv, err := get(tx, key, val)
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if err != nil {
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return
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}
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kvs = append(kvs, kv)
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return nil
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})
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return
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}
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// Get retrieves a single key:value item.
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func (tx *TX) Get(key []byte) (kv *KV, err error) {
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val := tx.bu.Get(key)
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return get(tx, key, val)
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}
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// MGet retrieves multiple key:value items.
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func (tx *TX) MGet(keys ...[]byte) (kvs []*KV, err error) {
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for _, key := range keys {
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val := tx.bu.Get(key)
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kv, err := get(tx, key, val)
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if err != nil {
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return nil, err
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}
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kvs = append(kvs, kv)
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}
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return
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}
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// PGet retrieves the range of rows which are prefixed with `pre`.
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func (tx *TX) PGet(pre []byte) (kvs []*KV, err error) {
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cu := tx.bu.Cursor()
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for key, val := cu.Seek(pre); bytes.HasPrefix(key, pre); key, val = cu.Next() {
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kv, err := get(tx, key, val)
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if err != nil {
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return nil, err
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}
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kvs = append(kvs, kv)
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}
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return
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}
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// RGet retrieves the range of `max` rows between `beg` (inclusive) and
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// `end` (exclusive). To return the range in descending order, ensure
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// that `end` sorts lower than `beg` in the key value store.
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func (tx *TX) RGet(beg, end []byte, max uint64) (kvs []*KV, err error) {
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if max == 0 {
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max = math.MaxUint64
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}
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cu := tx.bu.Cursor()
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if bytes.Compare(beg, end) < 1 {
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for key, val := cu.Seek(beg); key != nil && max > 0 && bytes.Compare(key, end) < 0; key, val = cu.Next() {
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kv, err := get(tx, key, val)
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if err != nil {
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return nil, err
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}
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kvs = append(kvs, kv)
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max--
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}
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}
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if bytes.Compare(beg, end) > 1 {
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for key, val := cu.Seek(end); key != nil && max > 0 && bytes.Compare(beg, key) < 0; key, val = cu.Prev() {
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kv, err := get(tx, key, val)
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if err != nil {
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return nil, err
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}
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kvs = append(kvs, kv)
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max--
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}
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}
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return
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}
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// Put sets the value for a key.
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func (tx *TX) Put(key, val []byte) (err error) {
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if !tx.tx.Writable() {
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err = &TXError{err}
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return
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}
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if val, err = snap.Encode(val); err != nil {
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err = &DBError{err}
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return
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}
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if val, err = cryp.Encrypt(tx.ck, val); err != nil {
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err = &CKError{err}
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return
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}
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if err = tx.bu.Put(key, val); err != nil {
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err = &DBError{err}
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return
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}
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return
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}
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// CPut conditionally sets the value for a key if the existing value is equal
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// to the expected value. To conditionally set a value only if there is no
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// existing entry pass nil for the expected value.
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func (tx *TX) CPut(key, val, exp []byte) (err error) {
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if !tx.tx.Writable() {
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err = &TXError{err}
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return
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}
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now, _ := tx.Get(key)
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if !bytes.Equal(now.val, exp) {
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err = &KVError{err, key, now.val, exp}
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return
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}
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if val, err = snap.Encode(val); err != nil {
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err = &DBError{err}
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return
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}
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if val, err = cryp.Encrypt(tx.ck, val); err != nil {
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err = &CKError{err}
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return
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}
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if err = tx.bu.Put(key, val); err != nil {
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err = &DBError{err}
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return
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}
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return
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}
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// Del deletes a single key:value item.
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func (tx *TX) Del(key []byte) (err error) {
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if !tx.tx.Writable() {
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err = &TXError{err}
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return
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}
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if err = tx.bu.Delete(key); err != nil {
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err = &DBError{err}
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return
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}
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return
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}
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// CDel conditionally deletes a key if the existing value is equal to the
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// expected value.
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func (tx *TX) CDel(key, exp []byte) (err error) {
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if !tx.tx.Writable() {
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err = &TXError{err}
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return
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}
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now, _ := tx.Get(key)
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if !bytes.Equal(now.val, exp) {
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err = &KVError{err, key, now.val, exp}
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return
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}
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if err = tx.bu.Delete(key); err != nil {
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err = &DBError{err}
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return
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}
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return
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}
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// MDel deletes multiple key:value items.
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func (tx *TX) MDel(keys ...[]byte) (err error) {
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if !tx.tx.Writable() {
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err = &TXError{err}
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return
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}
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for _, key := range keys {
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if err = tx.bu.Delete(key); err != nil {
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err = &DBError{err}
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return
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}
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}
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return
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}
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// PDel deletes the range of rows which are prefixed with `pre`.
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func (tx *TX) PDel(pre []byte) (err error) {
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cu := tx.bu.Cursor()
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for key, _ := cu.Seek(pre); bytes.HasPrefix(key, pre); key, _ = cu.Seek(pre) {
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if err = tx.bu.Delete(key); err != nil {
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err = &DBError{err}
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return
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}
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}
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return
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}
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// RDel deletes the range of `max` rows between `beg` (inclusive) and
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// `end` (exclusive). To delete the range in descending order, ensure
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// that `end` sorts lower than `beg` in the key value store.
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func (tx *TX) RDel(beg, end []byte, max uint64) (err error) {
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if max == 0 {
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max = math.MaxUint64
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}
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if !tx.tx.Writable() {
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err = &TXError{err}
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return
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}
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cu := tx.bu.Cursor()
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if bytes.Compare(beg, end) < 1 {
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for key, _ := cu.Seek(beg); key != nil && max > 0 && bytes.Compare(key, end) < 0; key, _ = cu.Seek(beg) {
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if err = tx.bu.Delete(key); err != nil {
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err = &DBError{err}
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return
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}
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max--
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}
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}
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if bytes.Compare(beg, end) > 1 {
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for key, _ := cu.Seek(end); key != nil && max > 0 && bytes.Compare(beg, key) < 0; key, _ = cu.Seek(end) {
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if err = tx.bu.Delete(key); err != nil {
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err = &DBError{err}
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return
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}
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max--
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}
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}
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return
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}
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func (tx *TX) Close() (err error) {
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return tx.Rollback()
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}
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func (tx *TX) Commit() (err error) {
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return tx.tx.Commit()
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}
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func (tx *TX) Rollback() (err error) {
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return tx.tx.Rollback()
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}
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func get(tx *TX, key, val []byte) (kv *KV, err error) {
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kv = &KV{
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exi: (val != nil),
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key: key,
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val: val,
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}
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kv.val, err = cryp.Decrypt(tx.ck, kv.val)
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if err != nil {
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err = &CKError{err}
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return
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}
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kv.val, err = snap.Decode(kv.val)
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if err != nil {
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err = &DBError{err}
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return
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}
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return
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}
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