@daisugi/kintsugi/src/reuse_promise.ts

Kintsugi is a set of utilities to help build a fault tolerant services.

import { SimpleMemoryStore } from './simple_memory_store.js';
import { stringifyArgs } from './stringify_args.js';
import type { AsyncFn } from './types.js';

export function reusePromise(fn: AsyncFn) {
  const simpleMemoryStore = new SimpleMemoryStore();

  return async function (this: unknown, ...args: any[]) {
    const cacheKey = stringifyArgs(args) as string;
    const cacheResponse = simpleMemoryStore.get(cacheKey);
    if (cacheResponse.isSuccess) {
      return cacheResponse.getValue();
    }
    const response = fn.apply(this, args).then(
      (value: any) => {
        simpleMemoryStore.delete(cacheKey);
        return value;
      },
      (reason: any) => {
        simpleMemoryStore.delete(cacheKey);
        throw reason;
      },
    );
    simpleMemoryStore.set(cacheKey, response);
    return response;
  };
}