forked from tikv/client-go
/
memdb_snapshot.go
136 lines (121 loc) · 3.18 KB
/
memdb_snapshot.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
// 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/JK1Zhang/client-go/v3/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
}
}