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FullJitterBackoff.ts
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FullJitterBackoff.ts
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// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
import Backoff from './Backoff';
/**
* Implements the [Full Jitter algorithm](
* https://aws.amazon.com/blogs/architecture/exponential-backoff-and-jitter/)
* and also allows for specifying a fixed wait added to the full jitter backoff
* (which can be zero).
*/
export default class FullJitterBackoff implements Backoff {
private currentRetry: number = 0;
constructor(
private fixedWaitMs: number,
private shortBackoffMs: number,
private longBackoffMs: number
) {
if (this.fixedWaitMs < 0) {
this.fixedWaitMs = 0;
}
if (this.shortBackoffMs < 0) {
this.shortBackoffMs = 0;
}
if (this.longBackoffMs < 0) {
this.longBackoffMs = 0;
}
this.reset();
}
reset(): void {
this.currentRetry = 0;
}
nextBackoffAmountMs(): number {
const fullJitterMs =
Math.random() *
Math.min(this.longBackoffMs, this.shortBackoffMs * Math.pow(2.0, this.currentRetry)) +
this.fixedWaitMs;
this.currentRetry += 1;
return fullJitterMs;
}
}