blob: 25f7b54d31c62c6c1e8d7703fe81bac4b353d8e6 (
plain)
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
|
export type FetchFunction<K, V> = (key: K) => Promise<V>;
type ResolveReject<V> = Parameters<ConstructorParameters<typeof Promise<V>>[0]>;
type ResolverPair<V> = {
resolve: ResolveReject<V>[0];
reject: ResolveReject<V>[1];
};
export class DebounceLoader<K, V> {
private resolverMap = new Map<K, ResolverPair<V>>();
private promiseMap = new Map<K, Promise<V>>();
private resolvedPromise = Promise.resolve();
constructor(private loadFn: FetchFunction<K, V>) {}
public load(key: K): Promise<V> {
const promise = this.promiseMap.get(key);
if (typeof promise !== 'undefined') {
return promise;
}
const isFirst = this.promiseMap.size === 0;
const newPromise = new Promise<V>((resolve, reject) => {
this.resolverMap.set(key, { resolve, reject });
});
this.promiseMap.set(key, newPromise);
if (isFirst) {
this.enqueueDebouncedLoadJob();
}
return newPromise;
}
private runDebouncedLoad(): void {
const resolvers = [...this.resolverMap];
this.resolverMap.clear();
this.promiseMap.clear();
for (const [key, { resolve, reject }] of resolvers) {
this.loadFn(key).then(resolve, reject);
}
}
private enqueueDebouncedLoadJob(): void {
this.resolvedPromise.then(() => {
process.nextTick(() => {
this.runDebouncedLoad();
});
});
}
}
|
