53 lines
1.5 KiB
TypeScript
53 lines
1.5 KiB
TypeScript
/*
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Copyright 2022 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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export class AsyncQueue<T, V> {
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private isRunning = false;
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private queue: T[] = [];
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private error?: Error;
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constructor(
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private readonly reducer: (v: V, t: T) => Promise<V>,
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private value: V,
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private readonly contains: (t: T, queue: T[]) => boolean = (t, queue) => queue.includes(t)
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) {}
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push(t: T) {
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if (this.contains(t, this.queue)) {
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return;
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}
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this.queue.push(t);
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this.runLoopIfNeeded();
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}
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private async runLoopIfNeeded() {
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if (this.isRunning || this.error) {
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return;
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}
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this.isRunning = true;
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try {
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let item: T | undefined;
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while (item = this.queue.shift()) {
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this.value = await this.reducer(this.value, item);
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}
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} catch (err) {
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this.error = err;
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} finally {
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this.isRunning = false;
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}
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}
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}
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