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-rw-r--r--server/helpers/promise-cache.ts21
1 files changed, 21 insertions, 0 deletions
diff --git a/server/helpers/promise-cache.ts b/server/helpers/promise-cache.ts
new file mode 100644
index 000000000..07e8a9962
--- /dev/null
+++ b/server/helpers/promise-cache.ts
@@ -0,0 +1,21 @@
1export class PromiseCache <A, R> {
2 private readonly running = new Map<string, Promise<R>>()
3
4 constructor (
5 private readonly fn: (arg: A) => Promise<R>,
6 private readonly keyBuilder: (arg: A) => string
7 ) {
8 }
9
10 run (arg: A) {
11 const key = this.keyBuilder(arg)
12
13 if (this.running.has(key)) return this.running.get(key)
14
15 const p = this.fn(arg)
16
17 this.running.set(key, p)
18
19 return p.finally(() => this.running.delete(key))
20 }
21}