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/*
This file is part of GNU Taler
(C) 2020 Taler Systems S.A.
GNU Taler is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
/**
* Helpers for dealing with retry timeouts.
*/
/**
* Imports.
*/
import { AbsoluteTime, Duration } from "@gnu-taler/taler-util";
export interface RetryInfo {
firstTry: AbsoluteTime;
nextRetry: AbsoluteTime;
retryCounter: number;
}
export interface RetryPolicy {
readonly backoffDelta: Duration;
readonly backoffBase: number;
readonly maxTimeout: Duration;
}
const defaultRetryPolicy: RetryPolicy = {
backoffBase: 1.5,
backoffDelta: { d_ms: 200 },
maxTimeout: { d_ms: 6000 },
};
export function updateRetryInfoTimeout(
r: RetryInfo,
p: RetryPolicy = defaultRetryPolicy,
): void {
const now = AbsoluteTime.now();
if (now.t_ms === "never") {
throw Error("assertion failed");
}
if (p.backoffDelta.d_ms === "forever") {
r.nextRetry = { t_ms: "never" };
return;
}
const nextIncrement =
p.backoffDelta.d_ms * Math.pow(p.backoffBase, r.retryCounter);
const t =
now.t_ms +
(p.maxTimeout.d_ms === "forever"
? nextIncrement
: Math.min(p.maxTimeout.d_ms, nextIncrement));
r.nextRetry = { t_ms: t };
}
export function getRetryDuration(
r: RetryInfo | undefined,
p: RetryPolicy = defaultRetryPolicy,
): Duration {
if (!r) {
// If we don't have any retry info, run immediately.
return { d_ms: 0 };
}
if (p.backoffDelta.d_ms === "forever") {
return { d_ms: "forever" };
}
const t = p.backoffDelta.d_ms * Math.pow(p.backoffBase, r.retryCounter);
return {
d_ms: p.maxTimeout.d_ms === "forever" ? t : Math.min(p.maxTimeout.d_ms, t),
};
}
export function resetRetryInfo(p: RetryPolicy = defaultRetryPolicy): RetryInfo {
const now = AbsoluteTime.now();
const info = {
firstTry: now,
nextRetry: now,
retryCounter: 0,
};
updateRetryInfoTimeout(info, p);
return info;
}
export namespace RetryInfo {
export function increment(
r: RetryInfo | undefined,
p: RetryPolicy = defaultRetryPolicy,
) {
if (!r) {
return resetRetryInfo(p);
}
const r2 = { ...r };
r2.retryCounter++;
updateRetryInfoTimeout(r2, p);
return r2;
}
}
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