指数回退策略应对服务限频

//使用逐步增加的方式来延迟重试某个操作
InitDelayValue = 100
For(Retries = 0; Retries < MAX_RETRIES; Retries = Retries+1)
        wait for (2^Retries * InitDelayValue) milliseconds
        Status = KmsApiRequest()
        IF Status == SUCCESS
            BREAK // Succeeded, stop calling the API again.
        ELSE IF Status = THROTTLED || Status == SERVER_NOT_READY
            CONTINUE // Failed due to throttling or server busy, try again.
        ELSE
            BREAK // another error occurs, stop calling the API again.
        END IF

# -*- coding: utf-8 -*-
import base64
import math
import time
import os
from tencentcloud.common import credential
from tencentcloud.common.exception.tencent_cloud_sdk_exception import TencentCloudSDKException
from tencentcloud.common.profile.client_profile import ClientProfile
from tencentcloud.common.profile.http_profile import HttpProfile
from tencentcloud.kms.v20190118 import kms_client, models


def KmsInit(region="ap-guangzhou", secretId="", secretKey=""):
          try:
                credProfile = credential.Credential(secretId, secretKey)
                client = kms_client.KmsClient(credProfile, region)
                return client
          except TencentCloudSDKException as err:
                print(err)
                return None

def BackoffFunction(RetryCount):
            InitDelayValue = 100
            DelayTime = math.pow(2, RetryCount) * InitDelayValue
            return DelayTime

if __name__ == '__main__':
            # 用户自定义参
            secretId = os.getenv('SECRET_ID')         # read from environment variable or use whitebox encryption to protect secret ID
            secretKey = os.getenv('SECRET_KEY')   # read from environment variable or use whitebox encryption to protect secret key    region = "ap-guangzhou"
            region = "ap-guangzhou"
            keyId = "replace-with-realkeyid"
            plaintext = "abcdefg123456789abcdefg123456789abcdefg"
            Retries = 0
            MaxRetries = 10
            client = KmsInit(region, secretId, secretKey)
            req = models.EncryptRequest()
            req.KeyId = keyId
            req.Plaintext = base64.b64encode(plaintext)
            while Retries < MaxRetries:
                try:
                    Retries += 1
                    rsp = client.Encrypt(req)  # 调用加密接口
                    print 'plaintext: ',plaintext,'CiphertextBlob: ',rsp.CiphertextBlob
                    break
                except TencentCloudSDKException as err:
                    if err.code == 'InternalError' or err.code == 'RequestLimitExceeded':
                        if Retries == MaxRetries: 
                            break
                        time.sleep(BackoffFunction(Retries + 1))
                        continue
                    else:
                        print(err)
                        break
                except Exception as err:
                    print(err)
                    break