init

.github/workflows/main.yml

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+name: CI Pipeline
+
+# trigger build when pushing, or when creating a pull request
+on: [push, pull_request]
+
+jobs:
+  build:
+    # run build on latest ubuntu
+    runs-on: ubuntu-latest
+    steps:
+      # this will check out the current branch (https://github.com/actions/checkout#Push-a-commit-using-the-built-in-token)
+      - uses: actions/checkout@v2
+      # installing Node
+      - name: Use Node.js 12.x
+        uses: actions/setup-node@v1
+        with:
+          # this will use the latest Node 12 version
+          node-version: 12.x
+      # install dependencies using clean install to avoid package lock updates
+      - run: yarn install
+      # finally run the tests
+      - run: yarn coverage
+      # Save coverage report in Coveralls
+      - name: Coveralls
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}

.gitignore

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+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+lerna-debug.log*
+lib
+.vscode
+node_modules
+
+# Diagnostic reports (https://nodejs.org/api/report.html)
+report.[0-9]*.[0-9]*.[0-9]*.[0-9]*.json
+
+# Runtime data
+pids
+*.pid
+*.seed
+*.pid.lock
+
+# Directory for instrumented libs generated by jscoverage/JSCover
+lib-cov
+
+# Coverage directory used by tools like istanbul
+coverage
+*.lcov
+
+# nyc test coverage
+.nyc_output
+
+# Grunt intermediate storage (https://gruntjs.com/creating-plugins#storing-task-files)
+.grunt
+
+# Bower dependency directory (https://bower.io/)
+bower_components
+
+# node-waf configuration
+.lock-wscript
+
+# Compiled binary addons (https://nodejs.org/api/addons.html)
+build/Release
+
+# Dependency directories
+node_modules/
+jspm_packages/
+
+# TypeScript v1 declaration files
+typings/
+
+# TypeScript cache
+*.tsbuildinfo
+
+# Optional npm cache directory
+.npm
+
+# Optional eslint cache
+.eslintcache
+
+# Microbundle cache
+.rpt2_cache/
+.rts2_cache_cjs/
+.rts2_cache_es/
+.rts2_cache_umd/
+
+# Optional REPL history
+.node_repl_history
+
+# Output of 'npm pack'
+*.tgz
+
+# Yarn Integrity file
+.yarn-integrity
+
+# dotenv environment variables file
+.env
+.env.test
+
+# parcel-bundler cache (https://parceljs.org/)
+.cache
+
+# Next.js build output
+.next
+
+# Nuxt.js build / generate output
+.nuxt
+dist
+
+# Gatsby files
+.cache/
+# Comment in the public line in if your project uses Gatsby and *not* Next.js
+# https://nextjs.org/blog/next-9-1#public-directory-support
+# public
+
+# vuepress build output
+.vuepress/dist
+
+# Serverless directories
+.serverless/
+
+# FuseBox cache
+.fusebox/
+
+# DynamoDB Local files
+.dynamodb/
+
+# TernJS port file
+.tern-port
+.coveralls.yml

README.md

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+# jsemaphore
+
+[![Coverage Status](https://coveralls.io/repos/github/Jannchie/jsemaphore/badge.svg?branch=main)](https://coveralls.io/github/Jannchie/jsemaphore?branch=main) [![Language grade: JavaScript](https://img.shields.io/lgtm/grade/javascript/g/Jannchie/jsemaphore.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/Jannchie/jsemaphore/context:javascript)
+
+## Usage
+
+``` ts
+import { parseCookies, stringifyCookies } from "jsemaphore";
+cookies = "test=value; name=jsemaphore";
+let cookiesMap = parseCookies(cookies);
+cookiesMap.set("test", "new_value");
+const cookiesString = stringifyCookies(cookiesMap);
+
+// jest
+expect(cookiesString).toBe("test=new_value; name=jsemaphore");
+```

jest.config.js

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+module.exports = {
+  roots: ["<rootDir>"],
+  transform: {
+    "^.+\\.(ts|tsx)$": "ts-jest",
+  },
+  testTimeout: 5000,
+};

package.json

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+{
+  "name": "jsemaphore",
+  "version": "1.0.0",
+  "description": "Simple semaphore, just like semaphore in python.",
+  "main": "lib/index.js",
+  "repository": "https://github.com/Jannchie/spider-cookies",
+  "author": "Jannchie <jannchie@gmail.com>",
+  "license": "MIT",
+  "typings": "typings",
+  "scripts": {
+    "coveralls": "jest --coverage && cat ./coverage/lcov.info | coveralls",
+    "coverage": "jest --coverage"
+  },
+  "devDependencies": {
+    "@types/jest": "^26.0.21",
+    "coveralls": "^3.1.0",
+    "jest": "^26.6.3",
+    "ts-jest": "^26.5.4",
+    "typescript": "^4.2.3"
+  },
+  "keywords": [
+    "semaphore"
+  ]
+}

src/semaphore.ts

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+type PromiseInfo = {
+  resolve: (value: unknown) => void;
+  reject: (reason?: any) => void;
+};
+export class Semaphore {
+  private count: number;
+  private concurrency: number;
+  private waitingTasks: PromiseInfo[];
+  constructor(concurrency: number) {
+    if (concurrency <= 0) {
+      throw new Error("Concurrency Should greater then 0!");
+    }
+    this.count = 0;
+    this.concurrency = concurrency;
+    this.waitingTasks = [];
+  }
+  async acquire() {
+    if (this.concurrency > this.count) {
+      this.count++;
+      return;
+    } else {
+      return new Promise((resolve, reject) => {
+        this.waitingTasks.push({ resolve, reject });
+      });
+    }
+  }
+  release() {
+    this.count--;
+    if (this.waitingTasks.length > 0 && this.count < this.concurrency) {
+      this.count++;
+      let promise = this.waitingTasks.shift()!;
+      promise.resolve(null);
+    }
+  }
+}

test/semaphore.test.ts

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+import { Semaphore } from "../src/semaphore";
+
+test("error", () => {
+  expect(() => {
+    new Semaphore(-1);
+  }).toThrow("Concurrency Should greater then 0!");
+  expect(() => {
+    new Semaphore(0);
+  }).toThrow("Concurrency Should greater then 0!");
+});
+
+test("base concurrency", async () => {
+  async function task(s: Semaphore) {
+    await new Promise((resolve) => setTimeout(() => resolve(null), 1000));
+    s.release();
+  }
+  const s = new Semaphore(1);
+  const start = performance.now();
+  const tasks = new Array<Promise<void>>();
+  for (let i = 0; i < 2; i++) {
+    await s.acquire();
+    tasks.push(task(s));
+  }
+  await Promise.all(tasks);
+  const end = performance.now();
+  expect(end - start).toBeGreaterThan(2000);
+});
+
+test("useless concurrency", async () => {
+  async function task(s: Semaphore) {
+    await new Promise((resolve) => setTimeout(() => resolve(null), 1000));
+    s.release();
+  }
+  const s = new Semaphore(10);
+  const start = performance.now();
+  const tasks = new Array<Promise<void>>();
+  for (let i = 0; i < 5; i++) {
+    await s.acquire();
+    tasks.push(task(s));
+  }
+  await Promise.all(tasks);
+  const end = performance.now();
+  expect(end - start).toBeLessThan(2000);
+});
+
+test("concurrency", async () => {
+  async function task(s: Semaphore) {
+    await new Promise((resolve) => setTimeout(() => resolve(null), 1000));
+    s.release();
+  }
+  const s = new Semaphore(10);
+  const start = performance.now();
+  const tasks = new Array<Promise<void>>();
+  for (let i = 0; i < 40; i++) {
+    await s.acquire();
+    tasks.push(task(s));
+  }
+  await Promise.all(tasks);
+  const end = performance.now();
+  expect(end - start).toBeGreaterThan(4000);
+});

tsconfig.json

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+{
+  "compilerOptions": {
+    "outDir": "lib",
+    "declarationDir": "typings",
+    "target": "es5",
+    "declarationMap": false,
+    "declaration": true,
+    "inlineSourceMap": true,
+    "moduleResolution": "Node",
+    "allowUmdGlobalAccess": true,
+    "allowSyntheticDefaultImports": true,
+    "resolveJsonModule": true,
+    "esModuleInterop": true,
+    "allowJs": true,
+    "skipLibCheck": true,
+    "downlevelIteration": true,
+    "strictNullChecks": true,
+    "noUnusedParameters": false,
+    "noImplicitReturns": true,
+    "noImplicitAny": false,
+    "noUnusedLocals": false,
+    "allowUnreachableCode": false,
+    "disableSizeLimit": true,
+    "disableReferencedProjectLoad": true,
+    "extendedDiagnostics": true,
+    "noImplicitUseStrict": true,
+    "noImplicitThis": true
+  },
+  "compileOnSave": true,
+  "include": ["src/**/*"]
+}