111 lines
2.8 KiB
TypeScript
111 lines
2.8 KiB
TypeScript
/*
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This file is part of GNU Taler
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(C) 2020 Taler Systems S.A.
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GNU Taler is free software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation; either version 3, or (at your option) any later version.
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GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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GNU Taler; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
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*/
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/**
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* Helpers for dealing with retry timeouts.
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*/
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/**
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* Imports.
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*/
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import { AbsoluteTime, Duration } from "@gnu-taler/taler-util";
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export interface RetryInfo {
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firstTry: AbsoluteTime;
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nextRetry: AbsoluteTime;
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retryCounter: number;
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}
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export interface RetryPolicy {
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readonly backoffDelta: Duration;
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readonly backoffBase: number;
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readonly maxTimeout: Duration;
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}
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const defaultRetryPolicy: RetryPolicy = {
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backoffBase: 1.5,
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backoffDelta: Duration.fromSpec({ seconds: 1 }),
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maxTimeout: Duration.fromSpec({ minutes: 2 }),
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};
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function updateTimeout(
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r: RetryInfo,
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p: RetryPolicy = defaultRetryPolicy,
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): void {
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const now = AbsoluteTime.now();
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if (now.t_ms === "never") {
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throw Error("assertion failed");
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}
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if (p.backoffDelta.d_ms === "forever") {
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r.nextRetry = { t_ms: "never" };
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return;
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}
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const nextIncrement =
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p.backoffDelta.d_ms * Math.pow(p.backoffBase, r.retryCounter);
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const t =
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now.t_ms +
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(p.maxTimeout.d_ms === "forever"
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? nextIncrement
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: Math.min(p.maxTimeout.d_ms, nextIncrement));
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r.nextRetry = { t_ms: t };
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}
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export namespace RetryInfo {
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export function getDuration(
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r: RetryInfo | undefined,
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p: RetryPolicy = defaultRetryPolicy,
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): Duration {
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if (!r) {
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// If we don't have any retry info, run immediately.
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return { d_ms: 0 };
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}
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if (p.backoffDelta.d_ms === "forever") {
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return { d_ms: "forever" };
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}
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const t = p.backoffDelta.d_ms * Math.pow(p.backoffBase, r.retryCounter);
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return {
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d_ms:
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p.maxTimeout.d_ms === "forever" ? t : Math.min(p.maxTimeout.d_ms, t),
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};
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}
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export function reset(p: RetryPolicy = defaultRetryPolicy): RetryInfo {
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const now = AbsoluteTime.now();
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const info = {
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firstTry: now,
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nextRetry: now,
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retryCounter: 0,
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};
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updateTimeout(info, p);
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return info;
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}
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export function increment(
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r: RetryInfo | undefined,
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p: RetryPolicy = defaultRetryPolicy,
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): RetryInfo {
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if (!r) {
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return reset(p);
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}
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const r2 = { ...r };
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r2.retryCounter++;
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updateTimeout(r2, p);
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return r2;
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}
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}
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