Class Latch

packages/effect/src/internal/effect/circular.ts:134–201

export const makeSemaphore = (permits: number) => core.sync(() => unsafeMakeSemaphore(permits))

class Latch extends Effectable.Class<void> implements Effect.Latch {
  waiters: Array<(_: Effect.Effect<void>) => void> = []
  scheduled = false
  constructor(private isOpen: boolean) {
    super()
  }

  commit() {
    return this.await
  }

  private unsafeSchedule(fiber: Fiber.RuntimeFiber<void>) {
    if (this.scheduled || this.waiters.length === 0) {
      return core.void
    }
    this.scheduled = true
    fiber.currentScheduler.scheduleTask(this.flushWaiters, fiber.getFiberRef(core.currentSchedulingPriority), fiber)
    return core.void
  }
  private flushWaiters = () => {
    this.scheduled = false
    const waiters = this.waiters
    this.waiters = []
    for (let i = 0; i < waiters.length; i++) {
      waiters[i](core.exitVoid)
    }
  }

  open = core.withFiberRuntime<void>((fiber) => {
    if (this.isOpen) {
      return core.void
    }
    this.isOpen = true
    return this.unsafeSchedule(fiber)
  })
  unsafeOpen() {
    if (this.isOpen) return
    this.isOpen = true
    this.flushWaiters()
  }
  release = core.withFiberRuntime<void>((fiber) => {
    if (this.isOpen) {
      return core.void
    }
    return this.unsafeSchedule(fiber)
  })
  await = core.asyncInterrupt<void>((resume) => {
    if (this.isOpen) {
      return resume(core.void)
    }
    this.waiters.push(resume)
    return core.sync(() => {
      const index = this.waiters.indexOf(resume)
      if (index !== -1) {
        this.waiters.splice(index, 1)
      }
    })
  })