Class UnboundedPubSubSubscription

repos/effect/packages/effect/src/PubSub.ts:2148–2255

    this.subscriberIndex = subscriberIndex
    this.unsubscribed = unsubscribed
  }

  isEmpty(): boolean {
    if (this.unsubscribed) {
      return true
    }
    let empty = true
    let loop = true
    while (loop) {
      if (this.subscriberHead === this.self.publisherTail) {
        loop = false
      } else {
        if (this.subscriberHead.next!.value !== AbsentValue) {
          empty = false
          loop = false
        } else {
          this.subscriberHead = this.subscriberHead.next!
          this.subscriberIndex += 1
        }
      }
    }
    return empty
  }

  size() {
    if (this.unsubscribed) {
      return 0
    }
    return this.self.publisherIndex - Math.max(this.subscriberIndex, this.self.subscribersIndex)
  }

  poll(): A | MutableList.Empty {
    if (this.unsubscribed) {
      return MutableList.Empty
    }
    let loop = true
    let polled: A | MutableList.Empty = MutableList.Empty
    while (loop) {
      if (this.subscriberHead === this.self.publisherTail) {
        loop = false
      } else {
        const elem = this.subscriberHead.next!.value
        if (elem !== AbsentValue) {
          polled = elem
          this.subscriberHead.subscribers -= 1
          if (this.subscriberHead.subscribers === 0) {
            this.self.publisherHead = this.self.publisherHead.next!
            this.self.publisherHead.value = AbsentValue
            this.self.subscribersIndex += 1
          }
          loop = false
        }
        this.subscriberHead = this.subscriberHead.next!
        this.subscriberIndex += 1
      }
    }
    return polled
  }