rolly-retry

A retry, failover library with types.

State

!npm version
!npm downloads

!license

!build
!coverage
!coverage
!coverage

Motivation

1. I needed a way to call a function n times until the call succeeds.
1. I needed to be able to define a successful call.
1. I wanted to try calling 1 or more different functions until one succeeded.

Usage

$3

``typescript
import { retry } from "rolly-retry";

/**
* call retriable_func("value")
* until the result === "success"
* up to 4 times
*/
await retry(
async () => await retriable_func("value"),
(result) => result === "success",
4
);
`

$3


`typescript
import { retry } from "rolly-retry";

/**
* call primary_retriable()
* until the result === "success"
* up to 4 times
* otherwise, call backup_retriable()
* until the result === "success"
* up to 4 times
*/
await retry(
[
async () => await primary_retriable(),
async () => await backup_retriable(),
],
(result) => result === "success",
4
);
`

$3

You can pass a back off to the retry. The back off will cause a delay after the first retry.
Backoffs reset for each function.

`typescript
import { retry } from "rolly-retry";

await retry(
[
async () => await func_i_want_to_try(1)
],
(result) => false,
3,
{
constant: 10, // constant 10ms delay after first try
linear: 20 // linear X20ms delay after first try
}
);
expect(calls).toBe(3);
/**
* Call Constant Linear Delay TotalMs
* 0: 0 0 0 0
* 1: 10 20 30 30
* 2: 10 40 50 80
*/
`

$3


`typescript
import { retry } from "rolly-retry";

let value = "";
await retry(() => (value += "a"), (result) => result === "aaa", 4);
expect(value).toBe("aaa");
`

Install

`
npm i rolly-retry
`

Avoid

$3

Function calls within a retry(func | [funcs]) operation are essentially synchronous. If you want to asynchronously retry many unrelated functions start multiple retries. e.g.,
`typescript
import { retry } from "rolly-retry";

const retryOne = retry(funcGroupOne, successOne, 2);
const retryTwo = retry(funcGroupTwo, successTwo, 2);
const allResults = await Promise.allSettled([retryOne, retryTwo]);
``