| 1 | import { isThrottlingError } from "@aws-sdk/service-error-classification";
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| 2 | export class DefaultRateLimiter {
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| 3 | constructor(options) {
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| 4 | this.currentCapacity = 0;
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| 5 | this.enabled = false;
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| 6 | this.lastMaxRate = 0;
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| 7 | this.measuredTxRate = 0;
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| 8 | this.requestCount = 0;
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| 9 | this.lastTimestamp = 0;
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| 10 | this.timeWindow = 0;
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| 11 | this.beta = options?.beta ?? 0.7;
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| 12 | this.minCapacity = options?.minCapacity ?? 1;
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| 13 | this.minFillRate = options?.minFillRate ?? 0.5;
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| 14 | this.scaleConstant = options?.scaleConstant ?? 0.4;
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| 15 | this.smooth = options?.smooth ?? 0.8;
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| 16 | const currentTimeInSeconds = this.getCurrentTimeInSeconds();
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| 17 | this.lastThrottleTime = currentTimeInSeconds;
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| 18 | this.lastTxRateBucket = Math.floor(this.getCurrentTimeInSeconds());
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| 19 | this.fillRate = this.minFillRate;
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| 20 | this.maxCapacity = this.minCapacity;
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| 21 | }
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| 22 | getCurrentTimeInSeconds() {
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| 23 | return Date.now() / 1000;
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| 24 | }
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| 25 | async getSendToken() {
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| 26 | return this.acquireTokenBucket(1);
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| 27 | }
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| 28 | async acquireTokenBucket(amount) {
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| 29 | if (!this.enabled) {
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| 30 | return;
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| 31 | }
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| 32 | this.refillTokenBucket();
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| 33 | if (amount > this.currentCapacity) {
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| 34 | const delay = ((amount - this.currentCapacity) / this.fillRate) * 1000;
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| 35 | await new Promise((resolve) => setTimeout(resolve, delay));
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| 36 | }
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| 37 | this.currentCapacity = this.currentCapacity - amount;
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| 38 | }
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| 39 | refillTokenBucket() {
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| 40 | const timestamp = this.getCurrentTimeInSeconds();
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| 41 | if (!this.lastTimestamp) {
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| 42 | this.lastTimestamp = timestamp;
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| 43 | return;
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| 44 | }
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| 45 | const fillAmount = (timestamp - this.lastTimestamp) * this.fillRate;
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| 46 | this.currentCapacity = Math.min(this.maxCapacity, this.currentCapacity + fillAmount);
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| 47 | this.lastTimestamp = timestamp;
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| 48 | }
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| 49 | updateClientSendingRate(response) {
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| 50 | let calculatedRate;
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| 51 | this.updateMeasuredRate();
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| 52 | if (isThrottlingError(response)) {
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| 53 | const rateToUse = !this.enabled ? this.measuredTxRate : Math.min(this.measuredTxRate, this.fillRate);
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| 54 | this.lastMaxRate = rateToUse;
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| 55 | this.calculateTimeWindow();
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| 56 | this.lastThrottleTime = this.getCurrentTimeInSeconds();
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| 57 | calculatedRate = this.cubicThrottle(rateToUse);
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| 58 | this.enableTokenBucket();
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| 59 | }
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| 60 | else {
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| 61 | this.calculateTimeWindow();
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| 62 | calculatedRate = this.cubicSuccess(this.getCurrentTimeInSeconds());
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| 63 | }
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| 64 | const newRate = Math.min(calculatedRate, 2 * this.measuredTxRate);
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| 65 | this.updateTokenBucketRate(newRate);
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| 66 | }
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| 67 | calculateTimeWindow() {
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| 68 | this.timeWindow = this.getPrecise(Math.pow((this.lastMaxRate * (1 - this.beta)) / this.scaleConstant, 1 / 3));
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| 69 | }
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| 70 | cubicThrottle(rateToUse) {
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| 71 | return this.getPrecise(rateToUse * this.beta);
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| 72 | }
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| 73 | cubicSuccess(timestamp) {
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| 74 | return this.getPrecise(this.scaleConstant * Math.pow(timestamp - this.lastThrottleTime - this.timeWindow, 3) + this.lastMaxRate);
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| 75 | }
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| 76 | enableTokenBucket() {
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| 77 | this.enabled = true;
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| 78 | }
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| 79 | updateTokenBucketRate(newRate) {
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| 80 | this.refillTokenBucket();
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| 81 | this.fillRate = Math.max(newRate, this.minFillRate);
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| 82 | this.maxCapacity = Math.max(newRate, this.minCapacity);
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| 83 | this.currentCapacity = Math.min(this.currentCapacity, this.maxCapacity);
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| 84 | }
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| 85 | updateMeasuredRate() {
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| 86 | const t = this.getCurrentTimeInSeconds();
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| 87 | const timeBucket = Math.floor(t * 2) / 2;
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| 88 | this.requestCount++;
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| 89 | if (timeBucket > this.lastTxRateBucket) {
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| 90 | const currentRate = this.requestCount / (timeBucket - this.lastTxRateBucket);
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| 91 | this.measuredTxRate = this.getPrecise(currentRate * this.smooth + this.measuredTxRate * (1 - this.smooth));
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| 92 | this.requestCount = 0;
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| 93 | this.lastTxRateBucket = timeBucket;
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| 94 | }
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| 95 | }
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| 96 | getPrecise(num) {
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| 97 | return parseFloat(num.toFixed(8));
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| 98 | }
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| 99 | }
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