64 lines
1.8 KiB
JavaScript
64 lines
1.8 KiB
JavaScript
"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.RWLock = void 0;
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const tslib_1 = require("tslib");
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const assert_1 = tslib_1.__importDefault(require("assert"));
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/**
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* 模拟一个读写锁，用于同步。
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* 注意，千万不要发生自己等自己
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*/
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class RWLock {
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readNumber;
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writeNumber;
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readWaiter;
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writeWaiter;
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constructor() {
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this.readNumber = 0;
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this.writeNumber = 0;
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this.readWaiter = [];
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this.writeWaiter = [];
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}
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async acquire(mode) {
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if (mode === 'S') {
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while (this.writeNumber > 0) {
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const p = new Promise((resolve) => this.readWaiter.push(resolve));
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await p;
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}
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this.readNumber++;
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}
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else {
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while (this.writeNumber || this.readNumber) {
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const p = new Promise((resolve) => this.writeWaiter.push(resolve));
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await p;
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}
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this.writeNumber++;
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}
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}
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release() {
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if (this.writeNumber) {
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(0, assert_1.default)(this.writeNumber === 1);
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this.writeNumber = 0;
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if (this.readWaiter.length > 0) {
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for (const f of this.readWaiter) {
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f(undefined);
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}
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this.readWaiter = [];
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}
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else if (this.writeWaiter.length > 0) {
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const f = this.writeWaiter.pop();
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f(undefined);
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}
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}
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else {
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(0, assert_1.default)(this.readNumber > 0);
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(0, assert_1.default)(this.readWaiter.length === 0);
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this.readNumber--;
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if (this.readNumber === 0) {
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const f = this.writeWaiter.pop();
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f && f(undefined);
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}
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}
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}
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}
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exports.RWLock = RWLock;
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