Class BoundedPubSubPow2

packages/effect/src/internal/pubsub.ts:402–494

@internal

/** @internal */
class BoundedPubSubPow2<in out A> implements AtomicPubSub<A> {
  array: Array<A>
  mask: number
  publisherIndex = 0
  subscribers: Array<number>
  subscriberCount = 0
  subscribersIndex = 0

  constructor(readonly capacity: number, readonly replayBuffer: ReplayBuffer<A> | undefined) {
    this.array = Array.from({ length: capacity })
    this.mask = capacity - 1
    this.subscribers = Array.from({ length: capacity })
  }

  replayWindow(): ReplayWindow<A> {
    return this.replayBuffer ? new ReplayWindowImpl(this.replayBuffer) : emptyReplayWindow
  }

  isEmpty(): boolean {
    return this.publisherIndex === this.subscribersIndex
  }

  isFull(): boolean {
    return this.publisherIndex === this.subscribersIndex + this.capacity
  }

  size(): number {
    return this.publisherIndex - this.subscribersIndex
  }

  publish(value: A): boolean {
    if (this.isFull()) {
      return false
    }
    if (this.subscriberCount !== 0) {
      const index = this.publisherIndex & this.mask
      this.array[index] = value
      this.subscribers[index] = this.subscriberCount
      this.publisherIndex += 1
    }
    if (this.replayBuffer) {
      this.replayBuffer.offer(value)
    }
    return true
  }

  publishAll(elements: Iterable<A>): Chunk.Chunk<A> {
    if (this.subscriberCount === 0) {
      if (this.replayBuffer) {
        this.replayBuffer.offerAll(elements)
      }
      return Chunk.empty()
    }
    const chunk = Chunk.fromIterable(elements)
    const n = chunk.length
    const size = this.publisherIndex - this.subscribersIndex
    const available = this.capacity - size
    const forPubSub = Math.min(n, available)