@ckeditor/ckeditor5-utils/src/retry.js

Miscellaneous utilities used by CKEditor 5.

/**
 * @license Copyright (c) 2003-2025, CKSource Holding sp. z o.o. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
 */
/**
 * @module utils/retry
 */
import wait from './wait.js';
/**
 * Tries calling the given callback until it sucessfully resolves.
 *
 * If the callback fails `maxAttempts` times, the returned promise is rejected with the last error.
 *
 * @typeParam TResult The result of a successful callback invocation.
 * @param callback The function to call until it succeeds.
 * @param options Configuration options.
 * @param options.maxAttempts Maximum number of attempts.
 * @param options.retryDelay The time in milliseconds between attempts. By default it implements exponential back-off policy.
 * @param options.signal The signal to abort further retries. The callback itself is not aborted automatically.
 */
export default async function retry(callback, options = {}) {
    const { maxAttempts = 4, retryDelay = exponentialDelay(), signal = (new AbortController()).signal } = options;
    signal.throwIfAborted();
    for (let attempt = 0;; attempt++) {
        try {
            return await callback();
        }
        catch (err) {
            const isLast = attempt + 1 >= maxAttempts;
            if (isLast) {
                throw err;
            }
        }
        await wait(retryDelay(attempt), { signal });
    }
}
/**
 * Creates a function that calculates exponential back-off delay. Pass it as `options.retryDelay` to {@link ~retry}.
 *
 * @param options.delay Base delay between invocations. Defaults to 1s.
 * @param options.factor How much to increase the delay. Defaults to 2x.
 * @param options.maxDelay Maximum timeout. Even if higher timeout is calculated, it cannot get higher than this value. Default to 10s.
 * @returns The function calculating the delay.
 */
export function exponentialDelay(options = {}) {
    const { delay = 1000, factor = 2, maxDelay = 10000 } = options;
    return attempt => Math.min(factor ** attempt * delay, maxDelay);
}