<A>(self: PubSub<A>): Effect.Effect<number>Returns the current number of messages retained by the PubSub for active
subscribers.
Details
If the PubSub has been shut down, the returned effect succeeds with 0.
The size is not a count of waiting subscribers or suspended publishers.
Example (Getting PubSub size)
import { Effect, PubSub } from "effect"
const program = Effect.gen(function*() {
const pubsub = yield* PubSub.bounded<string>(10)
// Initially empty
const initialSize = yield* PubSub.size(pubsub)
console.log("Initial size:", initialSize) // 0
yield* Effect.scoped(Effect.gen(function*() {
const subscription = yield* PubSub.subscribe(pubsub)
// Publish some messages for the active subscription
yield* PubSub.publish(pubsub, "msg1")
yield* PubSub.publish(pubsub, "msg2")
const afterPublish = yield* PubSub.size(pubsub)
console.log("After publishing:", afterPublish) // 2
yield* PubSub.takeAll(subscription)
}))
})export const const size: <A>(
self: PubSub<A>
) => Effect.Effect<number>
Returns the current number of messages retained by the PubSub for active
subscribers.
Details
If the PubSub has been shut down, the returned effect succeeds with 0.
The size is not a count of waiting subscribers or suspended publishers.
Example (Getting PubSub size)
import { Effect, PubSub } from "effect"
const program = Effect.gen(function*() {
const pubsub = yield* PubSub.bounded<string>(10)
// Initially empty
const initialSize = yield* PubSub.size(pubsub)
console.log("Initial size:", initialSize) // 0
yield* Effect.scoped(Effect.gen(function*() {
const subscription = yield* PubSub.subscribe(pubsub)
// Publish some messages for the active subscription
yield* PubSub.publish(pubsub, "msg1")
yield* PubSub.publish(pubsub, "msg2")
const afterPublish = yield* PubSub.size(pubsub)
console.log("After publishing:", afterPublish) // 2
yield* PubSub.takeAll(subscription)
}))
})
size = <function (type parameter) A in <A>(self: PubSub<A>): Effect.Effect<number>A>(self: PubSub<A>(parameter) self: {
pubsub: PubSub.Atomic<A>;
subscribers: PubSub.Subscribers<A>;
scope: Scope.Closeable;
shutdownHook: Latch.Latch;
shutdownFlag: MutableRef.MutableRef<boolean>;
strategy: PubSub.Strategy<A>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}
interface PubSub<in out A>A PubSub<A> is an asynchronous message hub into which publishers can publish
messages of type A and subscribers can subscribe to take messages of type
A.
Example (Publishing and subscribing to messages)
import { Effect, PubSub } from "effect"
const program = Effect.gen(function*() {
// Create a bounded PubSub with capacity 10
const pubsub = yield* PubSub.bounded<string>(10)
// Subscribe and consume messages
yield* Effect.scoped(Effect.gen(function*() {
const subscription = yield* PubSub.subscribe(pubsub)
// Publish messages
yield* PubSub.publish(pubsub, "Hello")
yield* PubSub.publish(pubsub, "World")
const message1 = yield* PubSub.take(subscription)
const message2 = yield* PubSub.take(subscription)
console.log(message1, message2) // "Hello", "World"
}))
})
Companion namespace containing the low-level building blocks used by
PubSub, including atomic implementations, backing subscriptions, replay
windows, and delivery strategies.
PubSub<function (type parameter) A in <A>(self: PubSub<A>): Effect.Effect<number>A>): import EffectEffect.type Effect.Effect = /*unresolved*/ anyEffect<number> => import EffectEffect.sync(() => const sizeUnsafe: <A>(
self: PubSub<A>
) => number
Returns the current number of messages retained by the PubSub for active
subscribers synchronously.
When to use
Use when an immediate PubSub size snapshot is needed outside effectful code
and concurrent changes between the check and later use are acceptable.
Details
Returns 0 after shutdown. Because this is an unsafe synchronous snapshot,
prefer size in effectful code.
Example (Reading size synchronously)
import { PubSub } from "effect"
// Unsafe synchronous size check
declare const pubsub: PubSub.PubSub<string>
const size = PubSub.sizeUnsafe(pubsub)
console.log("Current size:", size)
sizeUnsafe(self: PubSub<A>(parameter) self: {
pubsub: PubSub.Atomic<A>;
subscribers: PubSub.Subscribers<A>;
scope: Scope.Closeable;
shutdownHook: Latch.Latch;
shutdownFlag: MutableRef.MutableRef<boolean>;
strategy: PubSub.Strategy<A>;
pipe: { <A>(this: A): A; <A, B = never>(this: A, ab: (_: A) => B): B; <A, B = never, C = never>(this: A, ab: (_: A) => B, bc: (_: B) => C): C; <A, B = never, C = never, D = never>(this: A, ab: (_: A) => B, bc: (_: B) => C, cd: (_: C) => D): D; <…;
}