mirror of https://github.com/tikv/client-go.git
137 lines
3.2 KiB
Go
137 lines
3.2 KiB
Go
// Copyright 2021 TiKV Authors
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// NOTE: The code in this file is based on code from the
|
|
// TiDB project, licensed under the Apache License v 2.0
|
|
//
|
|
// https://github.com/pingcap/tidb/tree/cc5e161ac06827589c4966674597c137cc9e809c/store/tikv/unionstore/memdb_snapshot.go
|
|
//
|
|
|
|
// Copyright 2020 PingCAP, Inc.
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package unionstore
|
|
|
|
import (
|
|
tikverr "github.com/tikv/client-go/v2/error"
|
|
)
|
|
|
|
// SnapshotGetter returns a Getter for a snapshot of MemBuffer.
|
|
func (db *MemDB) SnapshotGetter() Getter {
|
|
return &memdbSnapGetter{
|
|
db: db,
|
|
cp: db.getSnapshot(),
|
|
}
|
|
}
|
|
|
|
// SnapshotIter returns a Iterator for a snapshot of MemBuffer.
|
|
func (db *MemDB) SnapshotIter(start, end []byte) Iterator {
|
|
it := &memdbSnapIter{
|
|
MemdbIterator: &MemdbIterator{
|
|
db: db,
|
|
start: start,
|
|
end: end,
|
|
},
|
|
cp: db.getSnapshot(),
|
|
}
|
|
it.init()
|
|
return it
|
|
}
|
|
|
|
func (db *MemDB) getSnapshot() MemDBCheckpoint {
|
|
if len(db.stages) > 0 {
|
|
return db.stages[0]
|
|
}
|
|
return db.vlog.checkpoint()
|
|
}
|
|
|
|
type memdbSnapGetter struct {
|
|
db *MemDB
|
|
cp MemDBCheckpoint
|
|
}
|
|
|
|
func (snap *memdbSnapGetter) Get(key []byte) ([]byte, error) {
|
|
x := snap.db.traverse(key, false)
|
|
if x.isNull() {
|
|
return nil, tikverr.ErrNotExist
|
|
}
|
|
if x.vptr.isNull() {
|
|
// A flag only key, act as value not exists
|
|
return nil, tikverr.ErrNotExist
|
|
}
|
|
v, ok := snap.db.vlog.getSnapshotValue(x.vptr, &snap.cp)
|
|
if !ok {
|
|
return nil, tikverr.ErrNotExist
|
|
}
|
|
return v, nil
|
|
}
|
|
|
|
type memdbSnapIter struct {
|
|
*MemdbIterator
|
|
value []byte
|
|
cp MemDBCheckpoint
|
|
}
|
|
|
|
func (i *memdbSnapIter) Value() []byte {
|
|
return i.value
|
|
}
|
|
|
|
func (i *memdbSnapIter) Next() error {
|
|
i.value = nil
|
|
for i.Valid() {
|
|
if err := i.MemdbIterator.Next(); err != nil {
|
|
return err
|
|
}
|
|
if i.setValue() {
|
|
return nil
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (i *memdbSnapIter) setValue() bool {
|
|
if !i.Valid() {
|
|
return false
|
|
}
|
|
if v, ok := i.db.vlog.getSnapshotValue(i.curr.vptr, &i.cp); ok {
|
|
i.value = v
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (i *memdbSnapIter) init() {
|
|
if len(i.start) == 0 {
|
|
i.seekToFirst()
|
|
} else {
|
|
i.seek(i.start)
|
|
}
|
|
|
|
if !i.setValue() {
|
|
err := i.Next()
|
|
_ = err // memdbIterator will never fail
|
|
}
|
|
}
|