轮询任务状态

结构化数据文件不会立即生成。Display & Video 360 可能需要几秒到几小时的时间来生成 SDF。

如需确定任务是否已完成，请定期使用 sdfdownloadtasks.operations.get 检索操作，并检查 done 字段是否为 True，以及任务是否已完成。此过程称为“轮询”。

如果任务已完成，则会设置 response 或 error 字段。如果 error 字段已填充，则表示任务失败，并且结果 Status 对象中提供了有关失败的详细信息。如果 response 字段已填充，则表示 Display & Video 360 已成功生成 SDF。从 response.resourceName 中提供的位置下载生成的文件。

如果轮询实现代码效率低下，在检查需要很长时间才能生成的报告时，会消耗大量 API 请求配额。为了限制重试次数并节省配额，请使用指数退避算法。

以下展示了如何使用指数退避算法轮询 SDF 下载操作：

# 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))