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
|
// Remarks for SubscriptionHub:
// 1. Compared with 'push' sematics in rxjs subject, we need 'pull'. In other words, no subscription, no updating.
// 2. Make api easier to use and write less boilerplate codes.
//
// There might be some bugs, especially memory leaks and in asynchronization codes.
import { pull } from 'lodash';
export type Subscriber<TData> = (data: TData) => void;
export class Subscription {
constructor(private _onUnsubscribe: () => void) {}
unsubscribe(): void {
this._onUnsubscribe();
}
}
export class NoValue {}
export class SubscriptionLine<TData> {
private _current: TData | NoValue = new NoValue();
private _observers: Subscriber<TData>[] = [];
constructor(private config?: { onZeroObserver?: () => void }) {}
subscribe(subscriber: Subscriber<TData>): Subscription {
this._observers.push(subscriber);
if (!(this._current instanceof NoValue)) {
subscriber(this._current);
}
return new Subscription(() => this.unsubscribe(subscriber));
}
private unsubscribe(subscriber: Subscriber<TData>): void {
if (!this._observers.includes(subscriber)) return;
pull(this._observers, subscriber);
if (this._observers.length === 0) {
this?.config?.onZeroObserver?.();
}
}
next(value: TData): void {
this._current = value;
this._observers.forEach((observer) => observer(value));
}
nextWithOld(updator: (old: TData | NoValue) => TData): void {
const value = updator(this._current);
this._current = value;
this._observers.forEach((observer) => observer(value));
}
}
export interface ISubscriptionHub<TKey, TData> {
subscribe(key: TKey, subscriber: Subscriber<TData>): Subscription;
}
export class SubscriptionHub<TKey, TData>
implements ISubscriptionHub<TKey, TData> {
private keyToString: (key: TKey) => string;
private setup?: (
key: TKey,
next: (value: TData) => void,
line: SubscriptionLine<TData>
) => (() => void) | void;
private readonly subscriptionLineMap = new Map<
string,
{
line: SubscriptionLine<TData>;
destroyer: (() => void) | undefined;
destroyTimer?: number; // Cancel it when resubscribe.
}
>();
// setup is called after creating line and if it returns a function as destroyer, then when the line is destroyed the destroyer will be called.
constructor(config?: {
keyToString?: (key: TKey) => string;
setup?: (key: TKey, next: (value: TData) => void) => (() => void) | void;
}) {
this.keyToString =
config?.keyToString ??
((value): string => {
if (typeof value === 'string') return value;
else
throw new Error(
'Default keyToString function only pass string value.'
);
});
this.setup = config?.setup;
}
subscribe(key: TKey, subscriber: Subscriber<TData>): Subscription {
const keyString = this.keyToString(key);
const line = (() => {
const info = this.subscriptionLineMap.get(keyString);
if (info == null) {
const { setup } = this;
const newLine = new SubscriptionLine<TData>({
onZeroObserver: () => {
const i = this.subscriptionLineMap.get(keyString);
if (i != null) {
i.destroyTimer = window.setTimeout(() => {
i.destroyer?.();
this.subscriptionLineMap.delete(keyString);
}, 10000);
}
},
});
const destroyer = setup?.(key, newLine.next.bind(newLine), newLine);
this.subscriptionLineMap.set(keyString, {
line: newLine,
destroyer: destroyer != null ? destroyer : undefined,
});
return newLine;
} else {
if (info.destroyTimer != null) {
window.clearTimeout(info.destroyTimer);
info.destroyTimer = undefined;
}
return info.line;
}
})();
return line.subscribe(subscriber);
}
update(key: TKey, value: TData): void {
const keyString = this.keyToString(key);
const info = this.subscriptionLineMap.get(keyString);
if (info != null) {
info.line.next(value);
}
}
updateWithOld(key: TKey, updator: (old: TData | NoValue) => TData): void {
const keyString = this.keyToString(key);
const info = this.subscriptionLineMap.get(keyString);
if (info != null) {
info.line.nextWithOld(updator);
}
}
}
|
