Class: RedisPubSub

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:43

Redis-backed implementation of the PubSubEngine contract.

Uses two separate ioredis connections — one for publishing (PUBLISH) and one dedicated to blocking subscribe commands (SUBSCRIBE / PSUBSCRIBE). This separation is required because a Redis client in subscribe mode can only issue subscribe/unsubscribe commands.

Construct via GraphQLPubSubModule.forRoot or GraphQLPubSubModule.forRootAsync in module-based apps.

Example

const pubsub = new RedisPubSub({ connection: { host: "localhost", port: 6379 } });

// Publish
await pubsub.publish("ORDER_CREATED", { id: 1 });

// Subscribe
const subId = await pubsub.subscribe("ORDER_CREATED", (payload) => {
  console.log(payload);
});

// Later…
pubsub.unsubscribe(subId);
await pubsub.close();

Implements

• PubSubEngine

Accessors

channelCount

Get Signature

get channelCount(): number;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:384

Number of distinct Redis channels (after triggerTransform) that this instance is currently subscribed to.

Returns

number

---

subscriptionCount

Get Signature

get subscriptionCount(): number;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:376

Number of active per-iterator subscriptions currently held in memory.

Useful for exporting as a metric — steady growth here when client churn is normal is a sign that subscription iterators aren't being returned on disconnect (typically a dirty-WebSocket-close issue).

Returns

number

Constructors

Constructor

new RedisPubSub(options?): RedisPubSub;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:71

Parameters

Parameter	Type
options	RedisPubSubOptions

Returns

RedisPubSub

Methods

asyncIterator()

asyncIterator<T>(triggers, options?): AsyncIterator<T>;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:346

Creates an AsyncIterator over the given triggers for use in GraphQL subscription resolvers.

Type Parameters

Type Parameter
T

Parameters

Parameter	Type
triggers	string | string[]
options?	AsyncIteratorOptions

Returns

AsyncIterator<T>

Example

// In a GraphQL resolver:
subscribe() {
  return pubsub.asyncIterator<OrderCreatedEvent>("ORDER_CREATED");
}

Implementation of

PubSubEngine.asyncIterator

---

close()

close(): Promise<void>;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:417

Gracefully closes both Redis connections.

Call this during application shutdown to allow open sockets to drain.

Returns

Promise<void>

---

debug()

debug(): {
  channelCount: number;
  channels: {
     subscribers: number;
     trigger: string;
  }[];
  subscriptionCount: number;
};

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:396

Snapshot of the subscription state for observability.

The returned structure is a copy — mutating it does not affect the internal maps. Intended for /health endpoints, metric collectors, and regression tests for leak detection. Preferable to reaching into subscriptionMap via as unknown as { subscriptionMap }.

Returns

{
  channelCount: number;
  channels: {
     subscribers: number;
     trigger: string;
  }[];
  subscriptionCount: number;
}

Name	Type	Defined in
channelCount	number	packages/graphql-pubsub/src/redis-pubsub.ts:398
channels	{ subscribers: number; trigger: string; }[]	packages/graphql-pubsub/src/redis-pubsub.ts:399
subscriptionCount	number	packages/graphql-pubsub/src/redis-pubsub.ts:397

---

getPublisher()

getPublisher(): Redis;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:365

Returns the underlying publisher Redis client.

Returns

Redis

---

getSubscriber()

getSubscriber(): Redis;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:360

Returns the underlying subscriber Redis client.

Returns

Redis

Warning

Do not issue regular Redis commands on this client — it is in subscribe mode and only accepts (P)SUBSCRIBE / (P)UNSUBSCRIBE.

---

publish()

publish(trigger, payload): Promise<void>;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:142

Publishes payload to the Redis channel derived from trigger.

The payload is serialised with the custom RedisPubSubOptions.serializer when provided, otherwise JSON.stringify.

Parameters

Parameter	Type
trigger	string
payload	unknown

Returns

Promise<void>

Implementation of

PubSubEngine.publish

---

subscribe()

subscribe<T>(
   trigger, 
   onMessage, 
   options?
): Promise<number>;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:160

Subscribes to trigger and invokes onMessage for every incoming message.

If another subscriber already holds a subscription for the same resolved channel, the existing Redis subscription is reused — no additional SUBSCRIBE command is issued.

Type Parameters

Type Parameter	Default type
T	unknown

Parameters

Parameter	Type
trigger	string
onMessage	MessageHandler<T>
options	SubscriptionOptions

Returns

Promise<number>

A numeric subscription ID used with unsubscribe.

Implementation of

PubSubEngine.subscribe

---

unsubscribe()

unsubscribe(subId): void;

Defined in: packages/graphql-pubsub/src/redis-pubsub.ts:298

Cancels the subscription identified by subId.

When the cancelled subscription was the last one for its Redis channel, the corresponding UNSUBSCRIBE / PUNSUBSCRIBE command is issued.

Parameters

Parameter	Type
subId	number

Returns

void

Throws

If subId is not a known subscription.

Implementation of

PubSubEngine.unsubscribe