Created
October 29, 2023 20:17
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import { | |
Chunk, | |
Deferred, | |
Duration, | |
Effect, | |
Queue, | |
Ref, | |
Request, | |
RequestResolver, | |
} from "effect" | |
interface DataLoaderItem<A extends Request.Request<any, any>> { | |
readonly request: A | |
readonly deferred: Deferred.Deferred< | |
Request.Request.Error<A>, | |
Request.Request.Success<A> | |
> | |
} | |
export const dataLoader = <A extends Request.Request<any, any>>( | |
self: RequestResolver.RequestResolver<A, never>, | |
options: { | |
readonly window: Duration.DurationInput | |
readonly maxBatchSize?: number | |
}, | |
) => | |
Effect.gen(function* (_) { | |
const queue = yield* _(Queue.unbounded<DataLoaderItem<A>>()) | |
const batch = yield* _(Ref.make(Chunk.empty<DataLoaderItem<A>>())) | |
const takeOne = Effect.flatMap(Queue.take(queue), item => | |
Ref.updateAndGet(batch, Chunk.append(item)), | |
) | |
const takeRest = takeOne.pipe( | |
Effect.repeatUntil( | |
items => | |
options.maxBatchSize !== undefined && | |
items.length >= options.maxBatchSize, | |
), | |
Effect.timeout(options.window), | |
Effect.zipRight(Ref.getAndSet(batch, Chunk.empty())), | |
) | |
yield* _( | |
takeOne, | |
Effect.zipRight(takeRest), | |
Effect.flatMap( | |
Effect.filter(({ deferred }) => Deferred.isDone(deferred), { | |
negate: true, | |
}), | |
), | |
Effect.flatMap( | |
Effect.forEach( | |
({ request, deferred }) => | |
Effect.flatMap(Effect.exit(Effect.request(request, self)), exit => | |
Deferred.complete(deferred, exit), | |
), | |
{ batching: true, discard: true }, | |
), | |
), | |
Effect.forever, | |
Effect.forkScoped, | |
) | |
return RequestResolver.fromFunctionEffect((request: A) => | |
Effect.flatMap( | |
Deferred.make<Request.Request.Error<A>, Request.Request.Success<A>>(), | |
deferred => | |
Queue.offer(queue, { request, deferred }).pipe( | |
Effect.zipRight(Deferred.await(deferred)), | |
Effect.onInterrupt(() => Deferred.interrupt(deferred)), | |
), | |
), | |
) | |
}) |
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