สถานะงานแบบสำรวจ

การสร้างไฟล์ข้อมูลที่มีโครงสร้าง (SDF) อาจใช้เวลาตั้งแต่ 2-3 วินาทีไปจนถึงหลายชั่วโมง งานจะเสร็จสมบูรณ์เมื่อฟิลด์ done ใน Operation เป็น True

Operation จะระบุด้วยชื่อในรูปแบบ /sdfdownloadtasks/operations/{id} เรียกข้อมูล Operation ที่มีชื่อนี้เป็นประจำโดยใช้ sdfdownloadtasks.operations.get เพื่อดูว่างานเสร็จสิ้นแล้วหรือไม่ กระบวนการนี้เรียกว่า "การสำรวจ"

หาก done เป็น True ระบบจะตั้งค่าฟิลด์ response หรือ error งานที่ไม่สำเร็จจะตั้งค่าฟิลด์ error ออบเจ็กต์ Status ที่กำหนดจะให้รายละเอียดเกี่ยวกับความล้มเหลว งานที่สำเร็จจะตั้งค่าฟิลด์ response ดาวน์โหลด SDF ที่ได้จาก response.resourceName

การสำรวจที่ไม่มีประสิทธิภาพอาจใช้โควต้าคำขอ API จำนวนมาก จำกัดการลองใหม่และประหยัดโควต้าโดยใช้ Exponential Backoff

วิธีสำรวจงานดาวน์โหลด SDF โดยใช้ Exponential Backoff มีดังนี้

Java

// Provide the name of the sdfdownloadtask operation.
String operationName = operation-name;

// Configure the Operations.get request.
Sdfdownloadtasks.Operations.Get operationRequest =
    service.sdfdownloadtasks().operations().get(operationName);

// Configure exponential backoff for checking the status of our operation.
ExponentialBackOff backOff =
    new ExponentialBackOff.Builder()
        .setInitialIntervalMillis(5000) // setting initial interval to five seconds
        .setMaxIntervalMillis(5000 * 60) // setting max interval to five minutes
        .setMaxElapsedTimeMillis(5000 * 60 * 60) // setting max elapsed time to five hours
        .build();
long backoffMillis = 0;

// Create default operation variable.
Operation operation = new Operation();

do {
  // Sleep before retrieving operation again.
  Thread.sleep(backoffMillis);

  // Retrieve operation.
  operation = operationRequest.execute();

  // If operation is not done, calculate next sleep period.
  if (operation.getDone() == null) {
    backoffMillis = backOff.nextBackOffMillis();
    if (backoffMillis == ExponentialBackOff.STOP) {
      System.out.printf("The operation has taken more than five hours to complete.%n");
      break;
    }
    System.out.printf(
        "Operation %s is still running, sleeping for %s milliseconds.%n",
        operationName, backoffMillis);
  }
} while (operation.getDone() == null);

// Check whether operation finished with an error, or is completed and ready to download.
if (operation.getDone() != null) {
  if (operation.getError() != null) {
    System.out.printf(
        "The operation finished in error with code %s: %s%n",
        operation.getError().getCode(), operation.getError().getMessage());
  } else {
    System.out.printf(
        "The operation completed successfully. Resource %s was created.%n",
        operation.getResponse().get("resourceName").toString());
  }
}

Python

# 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

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))

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

sleep = 0
start_time = time.time()

while True:
  # Retrieve the operation.
  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)

PHP

// The following values control retry behavior while the task is processing.
// Minimum amount of time between polling requests. Defaults to 5 seconds.
$minRetryInterval = 5;
// Maximum amount of time between polling requests. Defaults to 5 minutes.
$maxRetryInterval = 300;
// Maximum amount of time to spend polling. Defaults to 5 hours.
$maxRetryElapsedTime = 18000;

// Provide the name of the sdfdownloadtask operation.
$operationName = operation-name;

// Poll operation.
$sleep = 0;
$startTime = time();
do {
    try {
        // Call the API, retrieving the SDF Download Task.
        $operation = $this->service->sdfdownloadtasks_operations->get(
            $operationName
        );
    } catch (\Exception $e) {
        $this->renderError($e);
        return;
    }

    // Check if retrieved operation is finished.
    if ($operation->getDone() === true) {
        if($operation->getError() !== null) {
            $error = $operation->getError();
            printf(
                'The operation finished in error with code %s: %s<br>',
                $error->setCode(),
                $error->setMessage()
            );
            break;
        } else {
            $response = $operation->getResponse();
            printf(
                'The operation completed successfully. Resource %s '
                    . 'was created.<br>',
                $response['resourceName']
            );
            break;
        }
    } elseif (time() - $startTime > self::MAX_RETRY_ELAPSED_TIME) {
        print '<p>SDF download task processing deadline exceeded</p>';
        break;
    }

    // Generate next sleep interval.
    $minInterval = max($minRetryInterval, $sleep);
    $maxInterval = max(
        $minRetryInterval,
        $sleep * 3
    );
    $sleep = min($maxRetryInterval, rand($minInterval, $maxInterval));

    // Sleep a determined amount of time before retrieving the operation
    // again.
    printf(
        'Operation %s is still running, sleeping for %d seconds<br>',
        $operationName,
        $sleep
    );
    sleep($sleep);
} while (true);