Class: PubSubAsyncIterator<T>

Defined in: packages/graphql-pubsub/src/pubsub-async-iterator.ts:31

Async iterator for GraphQL subscriptions backed by a PubSubEngine.

Implements the AsyncIterator / AsyncIterable protocols so it can be used directly in GraphQL resolvers:

yield* pubsub.asyncIterator<MyEvent>("MY_EVENT");

Internally it maintains two queues:

• pullQueue – pending next() promises waiting for a message.
• pushQueue – messages that arrived before next() was called.

To prevent unbounded memory growth the push-queue is capped at MAX_QUEUE_SIZE; oldest entries are dropped when the limit is exceeded (similar to a lossy channel).

Type Parameters

Type Parameter
T

Implements

• AsyncIterator<T>

Constructors

Constructor

new PubSubAsyncIterator<T>(
   pubsub, 
   triggers, 
   options?
): PubSubAsyncIterator<T>;

Defined in: packages/graphql-pubsub/src/pubsub-async-iterator.ts:54

Parameters

Parameter	Type
pubsub	PubSubEngine
triggers	string[]
options?	AsyncIteratorOptions

Returns

PubSubAsyncIterator<T>

Methods

[asyncIterator]()

asyncIterator: AsyncIterator<T>;

Defined in: packages/graphql-pubsub/src/pubsub-async-iterator.ts:112

Makes this object usable in for await…of loops.

Returns

AsyncIterator<T>

---

next()

next(): Promise<IteratorResult<T, any>>;

Defined in: packages/graphql-pubsub/src/pubsub-async-iterator.ts:80

Returns the next message, waiting if none is buffered yet.

Returns

Promise<IteratorResult<T, any>>

Implementation of

AsyncIterator.next

---

return()

return(): Promise<IteratorResult<T, any>>;

Defined in: packages/graphql-pubsub/src/pubsub-async-iterator.ts:98

Terminates the iterator and unsubscribes from all triggers.

Returns

Promise<IteratorResult<T, any>>

Implementation of

AsyncIterator.return

---

throw()

throw(error): Promise<IteratorResult<T, any>>;

Defined in: packages/graphql-pubsub/src/pubsub-async-iterator.ts:105

Terminates the iterator, unsubscribes, then re-throws error.

Parameters

Parameter	Type
error	unknown

Returns

Promise<IteratorResult<T, any>>

Implementation of

AsyncIterator.throw