Define retry.setMaxCount

[parzhitsky]

Definition:

declare function setMaxCount(retryCount: number, onExceeded: "resolve" | "reject" = "reject"): void;
declare function setMaxCount(retryCount: number, onExceeded: () => unknown): void;

Usage:

(All actions here are limited to 3 attempts total: one initial attempt and two additional retries.)

retry.setMaxCount(2);
retry.setMaxCount(2, "reject");
// rejects with reason: "Maximum retry count exceeded after 2 retries (3 attempts total)"

retry.setMaxCount(2, "resolve");
// resolves `undefined` (a.k.a "silently fails")

retry.setMaxCount(2, () => reject("Could not do this"));
// rejects with reason: "Could not do this"

retry.setMaxCount(2, () => resolve(42));
// resolves `42`

Idempotence

Setting maximum retry count is an idempotent action, — only the first call (per each retry entity) will take effect. This also includes subsequent calls of the same line when retrying the attempt.

retryable((resolve, reject, retry) => {
  retry.setMaxCount(2); // <- first call sets limit to 2 retries / 3 attempts, next calls are ignored
  retry.setMaxCount(5); // <- ignored
  retry.setMaxCount(0); // <- ignored
  retry.setMaxCount(Infinity); // <- ignored
});

retryable((resolve, reject, retry) => {
  retry.setMaxCount(2); // <- first call sets limit to 2 retries / 3 attempts, next calls are ignored
  retry.setMaxCount(NaN); // <- ignored
});

retryable((resolve, reject, retry) => {
  retry.setMaxCount(NaN); // <- throws error (invalid retry count)
  // execution stops, anything after the erroneous line is a dead code
});

One big example with multiple retry entities:

await Promise.all([
  retryable((res, rej, retry) => {
    retry.setMaxCount(17); // <- first call sets limit to 17 retries / 18 attempts, next calls are ignored
    retry.setMaxCount(42); // <- ignored
  }),
  retryable((res, rej, retry) => {
    retry.setMaxCount(42); // <- first call sets limit to 42 retries / 43 attempts, next calls are ignored
    retry.setMaxCount(17); // <- ignored
  }),
]);

[parzhitsky]

I'm gonna rename setLimit to setMaxCount, since "limit" is ambiguous:

retry.setLimit(4); // how many attempts in total there are?

… while "max" clearly (almost clearly) conveys the idea:

retry.setMaxCount(4); // allowed 4 retries, 5 attempts in total; 6th attempt is disallowed