輪詢工作狀態

結構化資料檔案不會立即產生，Display & Video 360 可能需要幾秒到幾小時才能產生結構化資料檔案。

如要判斷工作是否完成，請定期使用 sdfdownloadtasks.operations.get 擷取作業，並檢查 done 欄位是否為 True，以及工作是否完成。這個程序稱為「輪詢」。

如果工作已完成，系統會設定 response 或 error 欄位。如果 error 欄位已填入資料，表示工作失敗，且失敗詳細資料會顯示在產生的 Status 物件中。如果「response」欄位已填入資料，表示 Display & Video 360 已成功產生結構化資料檔案。從 response.resourceName 中提供的位置下載產生的檔案。

如果輪詢實作項目效率不彰，檢查長時間執行的報表時，會耗用大量 API 請求配額。如要限制重試次數並節省配額，請使用指數輪詢。

以下是如何使用指數退避演算法輪詢 SDF 下載操作：

# Provide the name of the sdfdownloadtask operation.
operation_name = operation-name

# Set the following values that control retry behavior while the operation
# is running.
# Minimum amount of time between polling requests. Defaults to 5 seconds.
min_retry_interval = 5
# Maximum amount of time between polling requests. Defaults to 5 minutes.
max_retry_interval = 5 * 60
# Maximum amount of time to spend polling. Defaults to 5 hours.
max_retry_elapsed_time = 5 * 60 * 60

# Configure the sdfdownloadtasks.operations.get request.
get_request = service.sdfdownloadtasks().operations().get(operation_name)

sleep = 0

start_time = time.time()
while True:
  # Get current status of the report.
  operation = get_request.execute()

  if "done" in operation:
    if "error" in operation:
      print(
        f'The operation finished in error with code '
        f'{operation["error"]["code"]}: {operation["error"]["message"]}')
    else:
      print(
        f'The operation completed successfully. The resulting files can be '
        f'downloaded at {operation["response"]["resourceName"]}.')
    break
  elif time.time() - start_time > max_retry_elapsed_time:
    print("SDF generation deadline exceeded.")
    break

  sleep = next_sleep_interval(sleep)
  print(
    f'Operation {operation_name} is still running, sleeping for '
    f'{sleep} seconds.')
  time.sleep(sleep)

def next_sleep_interval(previous_sleep_interval):
  """Calculates the next sleep interval based on the previous."""
  min_interval = previous_sleep_interval or min_retry_interval
  max_interval = previous_sleep_interval * 3 or min_retry_interval
  return min(max_retry_interval, random.randint(min_interval, max_interval))