Relocate statics below constructor
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@@ -10,6 +10,31 @@ import { ExponentialBackoffStoppedRetriesError, ExponentialBackoffMaxRetriesHitE
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* The growth rate is the factor by which the delay increases with each attempt.
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*/
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export class ExponentialBackoff {
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private readonly options: ExponentialBackoffOptions;
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/**
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* Creates a new exponential-backoff instance.
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*
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* Unspecified options use the defaults listed below.
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*
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* @param options - Exponential-backoff configuration overrides.
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* @param options.maxDelay - Maximum delay between retries. Default: `10_000` ms.
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* @param options.maxAttempts - Maximum number of attempts; `0` retries indefinitely. Default: `10`.
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* @param options.baseDelay - Delay used as the basis for the first retry. Default: `1_000` ms.
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* @param options.growthRate - Multiplier applied to the delay after each attempt. Default: `2`.
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* @param options.jitter - Maximum proportional reduction subtracted from each delay (0–1). Default: `0.1`.
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*/
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constructor(options: Partial<ExponentialBackoffOptions> = {}) {
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this.options = {
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maxDelay: 10_000,
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maxAttempts: 10,
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baseDelay: 1_000,
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growthRate: 2,
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jitter: 0.1,
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...options,
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};
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}
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/**
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* Create a new ExponentialBackoff instance
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*
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@@ -43,29 +68,31 @@ export class ExponentialBackoff {
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return backoff.run(taskFn, onError);
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}
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private readonly options: ExponentialBackoffOptions;
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/**
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* Creates a new exponential-backoff instance.
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* Calculate the delay before we should attempt to retry
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*
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* Unspecified options use the defaults listed below.
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*
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* @param options - Exponential-backoff configuration overrides.
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* @param options.maxDelay - Maximum delay between retries. Default: `10_000` ms.
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* @param options.maxAttempts - Maximum number of attempts; `0` retries indefinitely. Default: `10`.
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* @param options.baseDelay - Delay used as the basis for the first retry. Default: `1_000` ms.
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* @param options.growthRate - Multiplier applied to the delay after each attempt. Default: `2`.
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* @param options.jitter - Maximum proportional reduction subtracted from each delay (0–1). Default: `0.1`.
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* @param options - The configuration for the exponential backoff
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* @param attempt - The current attempt number
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* @returns The time in milliseconds before another attempt should be made
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*/
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constructor(options: Partial<ExponentialBackoffOptions> = {}) {
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this.options = {
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maxDelay: 10_000,
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maxAttempts: 10,
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baseDelay: 1_000,
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growthRate: 2,
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jitter: 0.1,
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...options,
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};
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public static calculateDelay(options: ExponentialBackoffOptions, attempt: number): number {
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// Get the power of the growth rate
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const power = options.growthRate ** attempt;
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// Get the delay before jitter or limit
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const rawDelay = options.baseDelay * power;
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// Cap the delay to the maximum. Do this before the jitter so jitter does not become larger than delay
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const cappedDelay = Math.min(rawDelay, options.maxDelay);
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// Get a random number for the amount to "jitter" the delay by
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const jitterAmount = Math.random();
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// Calculate the jitter
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const jitter = jitterAmount * options.jitter * cappedDelay;
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// Subtract the jitter from the delay
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return cappedDelay - jitter;
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}
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/**
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@@ -142,33 +169,6 @@ export class ExponentialBackoff {
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// We completed the loop without ever succeeding. Throw an ExponentialBackoffMaxRetriesHitError with all the errors we got
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throw new ExponentialBackoffMaxRetriesHitError(errors);
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}
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/**
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* Calculate the delay before we should attempt to retry
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*
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* @param options - The configuration for the exponential backoff
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* @param attempt - The current attempt number
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* @returns The time in milliseconds before another attempt should be made
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*/
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public static calculateDelay(options: ExponentialBackoffOptions, attempt: number): number {
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// Get the power of the growth rate
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const power = options.growthRate ** attempt;
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// Get the delay before jitter or limit
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const rawDelay = options.baseDelay * power;
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// Cap the delay to the maximum. Do this before the jitter so jitter does not become larger than delay
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const cappedDelay = Math.min(rawDelay, options.maxDelay);
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// Get a random number for the amount to "jitter" the delay by
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const jitterAmount = Math.random();
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// Calculate the jitter
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const jitter = jitterAmount * options.jitter * cappedDelay;
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// Subtract the jitter from the delay
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return cappedDelay - jitter;
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}
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}
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export type ExponentialBackoffOptions = {
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