Choosing a broker

What it is

The broker is the only piece every producer and worker must agree on. gisila_queue ships three: InMemoryBroker, RedisBroker and RabbitBroker. Your task code doesn’t change between them.

When to use it

Situation	Broker
Unit and integration tests	`InMemoryBroker`
A single process that wants background work, losing in-flight tasks on crash is fine	`InMemoryBroker`
Production, several processes or hosts	`RedisBroker`
You also want results, dedupe, revoke, beat leader election, events	`RedisBroker` (everything else is Redis too)
You already run RabbitMQ and want its tooling and durability	`RabbitBroker` (+ Redis for results etc.)

Default to Redis. With GisilaQueue.redis one URL gives you broker, results, control channel, beat lock and state, and optional events, all namespaced.

When not to use it

Don’t use InMemoryBroker across processes or isolates; it is a Dart object.
Don’t point RedisBroker at Redis Cluster: its scripts touch keys derived from message contents, which Cluster doesn’t allow across slots. Use a single Redis or a primary with replicas.
Don’t pick RabbitMQ just for durability if you have no RabbitMQ yet; Redis with persistence (AOF) is simpler to run alongside the result backend you need anyway.

How it works

	InMemory	Redis	RabbitMQ
Delivery	at-most-once	at-least-once	at-least-once
Crash recovery	none	visibility timeout (5 min default)	on connection loss
Delayed messages	in-process list	sorted set, promoted about every second	TTL delay buckets (100 ms × 2ⁿ) with dead-letter exchange; no plugin
Idle workers	poll every 25 ms	`BLPOP` on notify lists (wake immediately)	push consumers
Queue priority	list order	list order	list order (local inbox)
Undecodable payloads	n/a	parked on `<prefix>:dead`	rejected (dropped)
CLI tools (`WorkerCli`, `inspect`, `rose`)	no	yes	no (build the app by hand)
`inspect` unacked count	n/a	`unackedCount()`	RabbitMQ management UI

The result backend, beat lock and state store, control channel and event transport have Redis and in-memory implementations only. A RabbitMQ deployment that needs results across processes uses RedisResultBackend next to RabbitBroker, with the same prefix.

Example

import 'package:gisila_queue/gisila_queue.dart';

GisilaQueue buildApp(String env) => switch (env) {
      'test' => GisilaQueue(broker: InMemoryBroker(), backend: InMemoryResultBackend()),
      'rabbit' => GisilaQueue(
          broker: RabbitBroker(host: 'rabbit', prefix: 'shop'),
          backend: RedisResultBackend(host: 'redis', prefix: 'shop'),
        ),
      _ => GisilaQueue.redis(namespace: 'shop', host: 'redis'),
    };