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51 lines
1.2 KiB
TypeScript
51 lines
1.2 KiB
TypeScript
/**
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* Copyright (c) Microsoft Corporation.
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*
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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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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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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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import { ManualPromise } from './manualPromise';
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export class Semaphore {
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private _max: number;
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private _acquired = 0;
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private _queue: ManualPromise[] = [];
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constructor(max: number) {
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this._max = max;
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}
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setMax(max: number) {
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this._max = max;
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}
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acquire(): Promise<void> {
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const lock = new ManualPromise();
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this._queue.push(lock);
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this._flush();
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return lock;
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}
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release() {
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--this._acquired;
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this._flush();
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}
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private _flush() {
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while (this._acquired < this._max && this._queue.length) {
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++this._acquired;
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this._queue.shift()!.resolve();
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}
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}
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}
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