-
Notifications
You must be signed in to change notification settings - Fork 144
/
TransactionDb.ts
157 lines (113 loc) · 3.24 KB
/
TransactionDb.ts
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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
// Copyright 2017-2019 @polkadot/db authors & contributors
// This software may be modified and distributed under the terms
// of the Apache-2.0 license. See the LICENSE file for details.
import { BaseDb, TxDb, ProgressCb } from '../types';
import { assert, isNull, logger } from '@polkadot/util';
interface OverlayItem {
key: Uint8Array;
value: Uint8Array | null;
}
const l = logger('db/transact');
export default class TransactionDb implements TxDb {
private backing: BaseDb;
private txOverlay: Map<string, OverlayItem> = new Map();
private txStarted: boolean;
constructor (backing: BaseDb) {
this.backing = backing;
this.txStarted = false;
}
public transaction<T> (fn: () => T): T {
l.debug((): string[] => ['transaction']);
try {
this.createTx();
const result = fn();
if (result) {
this.commitTx();
} else {
this.revertTx();
}
return result;
} catch (error) {
this.revertTx();
throw error;
}
}
public close (): void {
this.backing.close();
}
public open (): void {
this.backing.open();
}
public drop (): void {
this.backing.drop();
}
public empty (): void {
this.backing.empty();
}
public rename (base: string, file: string): void {
this.backing.rename(base, file);
}
public maintain (fn: ProgressCb): void {
assert(this.txStarted === false, 'Cannot maintain inside an open transaction');
this.backing.maintain(fn);
}
public size (): number {
return this.backing.size();
}
public del (key: Uint8Array): void {
if (this.txStarted) {
this.txOverlay.set(key.toString(), { key, value: null });
return;
}
this.backing.del(key);
}
public get (key: Uint8Array): Uint8Array | null {
// l.debug(() => ['get', u8aToHex(key)]);
if (this.txStarted) {
const value = this.txOverlay.get(key.toString());
if (value) {
return value.value;
}
}
return this.backing.get(key);
}
public put (key: Uint8Array, value: Uint8Array): void {
// l.debug(() => ['put', u8aToHex(key), u8aToHex(value)]);
if (this.txStarted) {
this.txOverlay.set(key.toString(), { key, value });
return;
}
return this.backing.put(key, value);
}
private createTx (): void {
l.debug((): string[] => ['createTx']);
assert(!this.txStarted, 'Cannot create a transaction when one is already active');
this.txOverlay.clear();
this.txStarted = true;
}
private commitTx (): void {
l.debug((): [string, number, string] => ['commitTx', Object.keys(this.txOverlay).length, 'keys']);
assert(this.txStarted, 'Cannot commit when not in transaction');
if (this.backing.txStart) {
this.backing.txStart();
}
this.txOverlay.forEach(({ key, value }): void => {
if (isNull(value)) {
this.backing.del(key);
} else {
this.backing.put(key, value);
}
});
if (this.backing.txCommit) {
this.backing.txCommit();
}
this.txOverlay.clear();
this.txStarted = false;
}
private revertTx (): void {
l.debug((): string[] => ['revertTx']);
assert(this.txStarted, 'Cannot revert when not in transaction');
this.txOverlay.clear();
this.txStarted = false;
}
}