65 lines
2.0 KiB
TypeScript
65 lines
2.0 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 type {MetricsInterface} from '@fluxer/media_proxy/src/types/Metrics';
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import type {TracingInterface} from '@fluxer/media_proxy/src/types/Tracing';
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export class InMemoryCoalescer {
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private pending = new Map<string, Promise<unknown>>();
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private metrics: MetricsInterface | undefined;
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private tracing: TracingInterface | undefined;
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constructor(options?: {metrics?: MetricsInterface | undefined; tracing?: TracingInterface | undefined}) {
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this.metrics = options?.metrics;
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this.tracing = options?.tracing;
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}
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async coalesce<T>(key: string, fn: () => Promise<T>): Promise<T> {
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const existing = this.pending.get(key) as Promise<T> | undefined;
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if (existing) {
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this.metrics?.counter({name: 'media_proxy.cache.hit'});
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this.tracing?.addSpanEvent('cache.hit', {cache_key: key});
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return existing;
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}
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this.metrics?.counter({name: 'media_proxy.cache.miss'});
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this.tracing?.addSpanEvent('cache.miss', {cache_key: key});
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const promise = (async () => {
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try {
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if (this.tracing) {
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return await this.tracing.withSpan(
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{
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name: 'cache.compute',
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attributes: {cache_key: key},
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},
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async () => fn(),
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);
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}
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return await fn();
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} finally {
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this.pending.delete(key);
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}
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})();
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this.pending.set(key, promise);
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return promise;
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}
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}
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