Dedup

createDedup() is an in-process key-set with fixed-window TTL. Use to drop duplicates of the same logical request inside a window - webhook delivery, idempotency keys, retry storms.

Setup

// src/lib/server/dedup.js
import { createDedup } from 'svelte-adapter-uws/plugins/dedup';

export const seen = createDedup({ ttlMs: 60_000 });

Usage

import { seen } from '$lib/server/dedup';

if (await seen.acquire(requestId)) {
  // First time we have seen this id within the window.
  await processWebhook(payload);
} else {
  // Duplicate - drop silently or return 200 OK to the sender.
}

API

Method	Description
`acquire(key)`	`true` if first time within the window; `false` for duplicates.
`has(key)`	Membership check without acquiring.
`delete(key)`	Force-evict a key.
`clear()`	Drop all entries.

Options

Option	Default	Description
`ttlMs`	`60000`	Window size in ms.
`maxKeys`	`1_000_000`	Capacity cap. Past the cap, oldest entries evict.
`maxIdLength`	`256`	Reject `acquire(key)` / `has(key)` / `delete(key)` calls where `key.length > maxIdLength` synchronously. Pass `Infinity` to disable.

The 256-char maxIdLength is a defense-in-depth bound. Pre-cap, a 1 MB wire-supplied key would anchor a 1 MB heap entry until the TTL elapsed. The cap throws synchronously with the actual length, so callers can log the offender.

Dedup

Setup

Usage

API

Options

See also