rate-limit/durable-object.mjs

Functions

Imports

It imports rate-limit/core.mjs. No module of this repo imports it.

Source

1// A Workers built-in, not an npm package.
2import { DurableObject } from "cloudflare:workers";
3import { hitRules, idleDeadline, purgeExpired } from "./core.mjs";
4
5/**
6 * The Durable Object class a Worker exports and binds (SQLite-backed). One instance per key holds
7 * every window for that key. After the longest window ends an alarm deletes its storage, so an idle
8 * key's instance is released.
9 *
10 * A Worker that already has a Durable Object class it cannot rename can extend this one: the counting
11 * lives in its own table, apart from anything the subclass stores.
12 */
13export class RateLimiter extends DurableObject {
14  /**
15   * @param {import("./core.mjs").Rule[]} rules
16   * @param {number} [nowMs]
17   */
18  async hit(rules, nowMs = Date.now()) {
19    // The count is one synchronous block (hitRules has no await); the alarm write follows it.
20    const result = hitRules(this.ctx.storage.sql, rules, nowMs);
21    if (result.ok) await this.ctx.storage.setAlarm(idleDeadline(rules, nowMs));
22    return result;
23  }
24
25  async alarm() {
26    const remaining = purgeExpired(this.ctx.storage.sql, Date.now());
27    if (remaining !== null) await this.ctx.storage.setAlarm(remaining);
28  }
29}