Class MailboxImpl

packages/effect/src/internal/mailbox.ts:72–468

const constDone = [empty, true] as const

class MailboxImpl<A, E> extends Effectable.Class<readonly [messages: Chunk.Chunk<A>, done: boolean], E>
  implements Api.Mailbox<A, E>
{
  readonly [TypeId]: Api.TypeId = TypeId
  readonly [ReadonlyTypeId]: Api.ReadonlyTypeId = ReadonlyTypeId
  private state: MailboxState<A, E> = {
    _tag: "Open",
    takers: new Set(),
    offers: new Set(),
    awaiters: new Set()
  }
  private messages: Array<A> = []
  private messagesChunk = Chunk.empty<A>()
  constructor(
    readonly scheduler: Scheduler,
    private capacity: number,
    readonly strategy: "suspend" | "dropping" | "sliding"
  ) {
    super()
  }

  offer(message: A): Effect<boolean> {
    return core.suspend(() => {
      if (this.state._tag !== "Open") {
        return exitFalse
      } else if (this.messages.length + this.messagesChunk.length >= this.capacity) {
        switch (this.strategy) {
          case "dropping":
            return exitFalse
          case "suspend":
            if (this.capacity <= 0 && this.state.takers.size > 0) {
              this.messages.push(message)
              this.releaseTaker()
              return exitTrue
            }
            return this.offerRemainingSingle(message)
          case "sliding":
            this.unsafeTake()
            this.messages.push(message)
            return exitTrue
        }
      }
      this.messages.push(message)
      this.scheduleReleaseTaker()
      return exitTrue
    })
  }
  unsafeOffer(message: A): boolean {
    if (this.state._tag !== "Open") {
      return false
    } else if (this.messages.length + this.messagesChunk.length >= this.capacity) {
      if (this.strategy === "sliding") {
        this.unsafeTake()
        this.messages.push(message)
        return true
      } else if (this.capacity <= 0 && this.state.takers.size > 0) {
        this.messages.push(message)
        this.releaseTaker()