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3 |
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4 | import {
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5 | BaseRequestPolicy,
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6 | RequestPolicy,
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7 | RequestPolicyOptionsLike,
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8 | RequestPolicyFactory,
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9 | } from "./requestPolicy";
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10 | import { WebResourceLike } from "../webResource";
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11 | import { HttpOperationResponse } from "../httpOperationResponse";
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12 | import { Constants } from "../util/constants";
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13 | import { delay } from "../util/utils";
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14 |
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15 | const StatusCodes = Constants.HttpConstants.StatusCodes;
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16 | const DEFAULT_RETRY_COUNT = 3;
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17 |
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18 |
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19 |
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20 |
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21 | export interface ThrottlingRetryOptions {
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22 | |
23 |
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24 |
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25 | maxRetries?: number;
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26 | }
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27 |
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28 | export function throttlingRetryPolicy(
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29 | maxRetries: number = DEFAULT_RETRY_COUNT
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30 | ): RequestPolicyFactory {
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31 | return {
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32 | create: (nextPolicy: RequestPolicy, options: RequestPolicyOptionsLike) => {
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33 | return new ThrottlingRetryPolicy(nextPolicy, options, maxRetries);
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34 | },
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35 | };
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36 | }
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37 |
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38 |
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39 |
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40 |
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41 |
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42 |
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43 |
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44 | export class ThrottlingRetryPolicy extends BaseRequestPolicy {
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45 | private retryLimit: number;
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46 |
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47 | constructor(nextPolicy: RequestPolicy, options: RequestPolicyOptionsLike, retryLimit: number) {
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48 | super(nextPolicy, options);
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49 | this.retryLimit = retryLimit;
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50 | }
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51 |
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52 | public async sendRequest(httpRequest: WebResourceLike): Promise<HttpOperationResponse> {
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53 | return this._nextPolicy.sendRequest(httpRequest.clone()).then((response) => {
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54 | return this.retry(httpRequest, response, 0);
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55 | });
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56 | }
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57 |
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58 | private async retry(
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59 | httpRequest: WebResourceLike,
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60 | httpResponse: HttpOperationResponse,
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61 | retryCount: number
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62 | ): Promise<HttpOperationResponse> {
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63 | if (httpResponse.status !== StatusCodes.TooManyRequests) {
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64 | return httpResponse;
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65 | }
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66 |
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67 | const retryAfterHeader: string | undefined = httpResponse.headers.get(
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68 | Constants.HeaderConstants.RETRY_AFTER
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69 | );
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70 |
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71 | if (retryAfterHeader && retryCount < this.retryLimit) {
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72 | const delayInMs: number | undefined = ThrottlingRetryPolicy.parseRetryAfterHeader(
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73 | retryAfterHeader
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74 | );
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75 | if (delayInMs) {
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76 | await delay(delayInMs);
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77 | const res = await this._nextPolicy.sendRequest(httpRequest);
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78 | return this.retry(httpRequest, res, retryCount + 1);
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79 | }
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80 | }
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81 |
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82 | return httpResponse;
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83 | }
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84 |
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85 | public static parseRetryAfterHeader(headerValue: string): number | undefined {
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86 | const retryAfterInSeconds = Number(headerValue);
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87 | if (Number.isNaN(retryAfterInSeconds)) {
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88 | return ThrottlingRetryPolicy.parseDateRetryAfterHeader(headerValue);
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89 | } else {
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90 | return retryAfterInSeconds * 1000;
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91 | }
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92 | }
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93 |
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94 | public static parseDateRetryAfterHeader(headerValue: string): number | undefined {
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95 | try {
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96 | const now: number = Date.now();
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97 | const date: number = Date.parse(headerValue);
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98 | const diff = date - now;
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99 |
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100 | return Number.isNaN(diff) ? undefined : diff;
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101 | } catch (error) {
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102 | return undefined;
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103 | }
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104 | }
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105 | }
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