check(index != -1)

    calls.removeAt(index)
    this.connection = null

    if (calls.isEmpty()) {
      connection.idleAtNs = System.nanoTime()
      if (connectionPool.connectionBecameIdle(connection)) {
        return connection.socket()
      }
    }

    return null
  }

  private fun timeoutExit(cause: IOException?): IOException? {
    if (timeoutEarlyExit) return cause