107 lines
2.8 KiB
TypeScript
107 lines
2.8 KiB
TypeScript
/*
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Copyright 2020 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 interface ILock {
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release(): void;
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}
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export class Lock implements ILock {
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private _promise?: Promise<void>;
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private _resolve?: (() => void);
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tryTake(): boolean {
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if (!this._promise) {
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this._promise = new Promise(resolve => {
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this._resolve = resolve;
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});
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return true;
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}
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return false;
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}
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async take(): Promise<void> {
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while(!this.tryTake()) {
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await this.released();
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}
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}
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get isTaken(): boolean {
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return !!this._promise;
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}
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release(): void {
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if (this._resolve) {
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this._promise = undefined;
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const resolve = this._resolve;
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this._resolve = undefined;
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resolve();
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}
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}
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released(): Promise<void> | undefined {
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return this._promise;
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}
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}
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export class MultiLock implements ILock {
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constructor(public readonly locks: Lock[]) {
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}
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release(): void {
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for (const lock of this.locks) {
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lock.release();
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}
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}
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}
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export function tests() {
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return {
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"taking a lock twice returns false": assert => {
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const lock = new Lock();
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assert.equal(lock.tryTake(), true);
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assert.equal(lock.isTaken, true);
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assert.equal(lock.tryTake(), false);
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},
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"can take a released lock again": assert => {
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const lock = new Lock();
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lock.tryTake();
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lock.release();
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assert.equal(lock.isTaken, false);
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assert.equal(lock.tryTake(), true);
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},
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"2 waiting for lock, only first one gets it": async assert => {
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const lock = new Lock();
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lock.tryTake();
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let first;
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lock.released()!.then(() => first = lock.tryTake());
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let second;
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lock.released()!.then(() => second = lock.tryTake());
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const promise = lock.released();
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lock.release();
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await promise;
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assert.strictEqual(first, true);
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assert.strictEqual(second, false);
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},
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"await non-taken lock": async assert => {
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const lock = new Lock();
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await lock.released();
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assert(true);
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}
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}
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}
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