NotFounds / deno-singleflight

provides a duplicate function call suppression

deno-singleflight

provides a duplicate function call suppression

Usage

import { SingleFlight } from "...";

const SG = new SingleFlight();
await SG
  .Do("foo", () => {
    const ret = heavy(); // heavy request/function
    return ret;
  })
  .then((res) => res);

Example for de-dup

import { SingleFlight } from "./mod.ts";

const SG = new SingleFlight();
const n = 5;

const promises: Promise<any>[] = [];
for (let i = 0; i < n; i++) {
  promises.push(SG.Do("bar", () => `${i}`));
}

Promise.all(promises).then((ret) => {
  ret.forEach((x) => console.log(x))
});

Running this returns the following result.

$ cat example.ts
import { SingleFlight } from "./mod.ts";

const SG = new SingleFlight();
const n = 5;

const promises: Promise<any>[] = [];
for (let i = 0; i < n; i++) {
  promises.push(SG.Do("bar", () => `${i}`));
}

Promise.all(promises).then((ret) => {
  ret.forEach((x) => console.log(x))
});

$ deno run example.ts
0
0
0
0
0

Only the first function call is evaluated.

References

• singleflight.go | sync/singleflight

License

Copyright © 2021 NotFounds.

This library is released under the MIT License.

---

This library is developed based on zcong1993/singleflight (LICENSE)