if (nanoTime >= waitUntil) return null
          val editCountBefore = editCount
          yieldUntil { nanoTime >= waitUntil || editCount > editCountBefore }
        }
      }
    }

    override fun put(element: T) {
      taskRunner.lock.withLock {
        delegate.put(element)
        editCount++
      }
    }

    override fun iterator() = error("unsupported")