54 lines
1.6 KiB
TypeScript
54 lines
1.6 KiB
TypeScript
/*
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* Copyright (C) 2026 Fluxer Contributors
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*
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* This file is part of Fluxer.
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*
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* Fluxer is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Fluxer is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
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*/
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import {Logger} from '@fluxer/api/src/Logger';
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import {recordCounter} from '@fluxer/telemetry/src/Metrics';
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import type {MiddlewareHandler} from 'hono';
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const MAX_CONCURRENT_REQUESTS = 500;
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const SKIP_PATHS = new Set(['/_health', '/internal/telemetry']);
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let inFlightRequests = 0;
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export const ConcurrencyLimitMiddleware: MiddlewareHandler = async (ctx, next) => {
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if (SKIP_PATHS.has(ctx.req.path)) {
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await next();
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return;
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}
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if (inFlightRequests >= MAX_CONCURRENT_REQUESTS) {
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recordCounter({name: 'api.concurrency_limit.rejected'});
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Logger.warn(
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{inFlightRequests, max: MAX_CONCURRENT_REQUESTS},
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'[concurrency-limit] Rejecting request, server at capacity',
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);
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ctx.header('Retry-After', '5');
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ctx.status(503);
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ctx.res = ctx.json({message: 'Server is at capacity, please retry shortly'}, 503);
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return;
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}
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inFlightRequests += 1;
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try {
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await next();
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} finally {
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inFlightRequests -= 1;
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}
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};
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