WRNexusJS/packages/queue/README.md

@wrnexus/queue

A background job queue with delays, retries + exponential backoff, recurring jobs, and concurrent workers.

Part of the WrNexus framework — an SSR-first, Bun-native full-stack web framework.

Overview

@wrnexus/queue is a server-side in-process job queue. You register named workers, enqueue jobs (optionally delayed or recurring), and let the queue poll and run them on a timer — with per-job retry limits and doubling backoff between attempts. The default store lives in memory; the design allows a pluggable driver to back it with Redis/SQL for durability across restarts. Reach for it when you need to defer work (emails, webhooks, cleanup) off the request path without a heavyweight external broker. Tests can drive it deterministically via drain().

Installation

bun add @wrnexus/queue

Private package — the machine must be authenticated to the wrnexus npm org (a read token in ~/.npmrc). Requires Bun (Node is not supported).

API

The package exports a single factory plus its supporting types.

createQueue(options?): Queue

Creates a new queue instance.

function createQueue(options?: QueueOptions): Queue;

QueueOptions

Option	Type	Default	Description
maxAttempts	number	3	Default max attempts per job before it is dead-lettered.
backoffMs	number	1000	Base retry backoff in ms; doubles per attempt.
pollMs	number	250	Poll interval used once start() is called (ms).
onFailed	(job: Job, error: unknown) => void	—	Called when a job exhausts its attempts.
concurrency	number	unlimited	Maximum jobs claimed by one drain() call.
capacity	number	unlimited	Maximum queued plus active jobs before adds reject.
now	() => number	Date.now	Clock injection for deterministic tests.

Queue

The object returned by createQueue.

Method	Signature	Description
add	add<T>(name, data: T, options?: AddOptions): Promise<Job<T>>	Enqueue a job under a worker name. Returns the created job.
process	process<T>(name, handler: JobHandler<T>): void	Register the worker that runs jobs of the given name.
drain	drain(now?: number): Promise<number>	Run every job whose runAt ≤ now, once. Returns how many ran.
start	start(): void	Begin polling every pollMs. No-op if already started.
stop	stop(): void	Stop the poll timer.
shutdown	shutdown({ force? }): Promise<void>	Stop accepting jobs and await active work; force aborts it.
size	size(): number	Number of jobs currently queued.
get/list	get(id) / list(name?)	Inspect defensive copies of pending jobs.
cancel	cancel(id): boolean	Remove queued work or abort an active handler.
failed	failed(): Job[]	Inspect exhausted jobs in the dead-letter collection.
retry	retry(id): Promise<boolean>	Reset and requeue a dead-lettered job.

AddOptions

Option	Type	Description
delayMs	number	Delay before the job becomes runnable (ms).
maxAttempts	number	Max attempts before dead-lettering. Defaults to the queue's maxAttempts.
repeat	number	Re-enqueue this job this many ms after each successful run (recurring).
priority	number	Higher values are selected first among due jobs.
idempotencyKey	string	Return the matching pending job instead of enqueueing a duplicate.

JobHandler<T>

type JobHandler<T = unknown> = (
  job: Job<T>,
  context: { signal: AbortSignal },
) => void | Promise<void>;

Job<T>

interface Job<T = unknown> {
  id: string; // e.g. "job_1"
  name: string;
  data: T;
  attempts: number;
  maxAttempts: number;
  runAt: number; // epoch ms; job runs when now ≥ runAt
  repeat?: number; // if set, re-enqueue this many ms after each success
}

Usage

Register workers, enqueue jobs, then start the poller:

import { createQueue } from "@wrnexus/queue";

const queue = createQueue({ maxAttempts: 3, backoffMs: 1000 });

// Register a worker for the "email" job name.
queue.process<{ to: string }>("email", async (job) => {
  await send(job.data.to);
});

// Enqueue a delayed job with up to 3 attempts.
await queue.add("email", { to: "a@b.com" }, { delayMs: 5000, maxAttempts: 3 });

queue.start(); // begin polling; queue.stop() to halt

Use context.signal in network/database calls so forced shutdown and active cancellation finish promptly. For process termination, prefer await queue.shutdown(); use { force: true } only after your grace period.

Durable queue

createDurableQueue({ store }) retains jobs until their handler succeeds and supports atomic leases when a driver implements QueueStore.claim. It exposes the same cancellation/shutdown behavior plus list, failed, and retry. The included memoryQueueStore() is useful for tests; production Redis/SQL drivers should make claim() atomic to prevent two workers executing one job.

Recurring jobs

Pass repeat to re-enqueue a job a fixed interval after each successful run:

queue.process("heartbeat", async () => ping());
await queue.add("heartbeat", {}, { repeat: 60_000 }); // runs ~every minute

Handling permanent failures

When a job's attempts reaches maxAttempts, it is dropped and onFailed fires instead of retrying:

const queue = createQueue({
  onFailed: (job, error) => {
    console.error(`job ${job.id} (${job.name}) gave up`, error);
  },
});

Deterministic testing

Instead of start(), inject a clock and drive the queue with drain():

let clock = 0;
const queue = createQueue({ now: () => clock });

queue.process("task", async () => {
  /* ... */
});
await queue.add("task", {}, { delayMs: 5000 });

clock = 5000;
const ran = await queue.drain(); // => 1

Durable workflows and approvals

createWorkflowEngine(store) executes dependency-ordered steps and persists every transition, result, progress update, failure, cancellation, and approval record. Approval steps pause safely and can resume after a process restart because the snapshot lives in the supplied WorkflowStore.

const workflow = defineDurableWorkflow({
  name: "publish-report",
  steps: [
    { name: "build", run: buildReport },
    { name: "approve", dependsOn: ["build"], approval: true, run: (report) => report },
    { name: "publish", dependsOn: ["approve"], run: publishReport },
  ],
});

const run = await engine.start(workflow, input);
await engine.approve(workflow, run.id, "approve", currentUser.id);

Use memoryWorkflowStore() for tests. Production stores implement the small get, put, and list contract using the same transactional database or durable service as the application.

Retry & backoff behavior

• On a thrown handler error, the job is retried while attempts < maxAttempts.
• The next runAt is set to now + backoffMs * 2^(attempts - 1) (exponential backoff): with backoffMs: 1000 the delays are 1s, 2s, 4s, …
• A job whose worker name has no registered handler stays queued until one is registered (it is not counted as runnable by drain).
• drain is re-entrant-safe: overlapping calls are skipped while one is running.

Requirements / Notes

• Bun-only runtime (Node is not supported), consistent with the rest of the WrNexus framework. The queue itself relies only on standard timers (setInterval/clearInterval) and has no runtime dependencies.
• The default store is in-process, so queued jobs do not survive a restart; a pluggable driver is intended for backing it with Redis/SQL for durability.
• Works alongside @wrnexus/core for offloading work from the request path.