@foxglove/ros1/src/backoff.ts

Standalone TypeScript implementation of the ROS 1 (Robot Operating System) protocol with a pluggable transport layer

// Implements truncated exponential backoff with jitter. Each retry, the backoff
// time is increased by 2^retries plus a random amount of jitter. The maximum
// time returned by this method is capped at `maxMs`.
export function backoffTime(
  retries: number,
  maxMs = 10000,
  maxJitterMs = 1000,
  rng: () => number = Math.random,
): number {
  const randomMs = rng() * maxJitterMs;
  return Math.min(Math.pow(2, retries) + randomMs, maxMs);
}

// Wait for a period of time determined by the truncated exponential backoff
// with jitter algorithm implemented in `backoffTime()`.
export async function backoff(
  retries: number,
  maxMs = 10000,
  maxJitterMs = 1000,
  rng: () => number = Math.random,
): Promise<void> {
  await new Promise((resolve) =>
    setTimeout(resolve, backoffTime(retries, maxMs, maxJitterMs, rng)),
  );
}

// Continue to call an async function until it completes without throwing an
// exception
export async function retryForever<T>(fn: () => Promise<T>): Promise<T> {
  let retries = 0;

  for (;;) {
    try {
      return await fn();
      // eslint-disable-next-line @typescript-eslint/no-unused-vars
    } catch (_err) {
      await backoff(++retries);
    }
  }
}