feat(add): async programming

js/async-programming/parallel/parallel-limit-version-2.ts

@@ -0,0 +1,39 @@
+import { delay } from '../util/delay';
+
+type AsyncFunction = () => Promise<unknown>;
+const limitOf = (max: number) => {
+  const mq: AsyncFunction[] = [];
+  let count = 0;
+
+  const runTask = async () => {
+    if (count < max) {
+      count++;
+      await mq.shift()!();
+      count--;
+      checkMq();
+    }
+  };
+
+  const checkMq = () => {
+    if (mq.length) runTask();
+  };
+
+  return (fn: AsyncFunction) => {
+    mq.push(fn);
+    checkMq();
+  };
+};
+
+// * ================================================================================
+
+const limit = limitOf(2);
+
+console.warn('start');
+
+for (let i = 1; i < 10; i++) {
+  limit(async () => {
+    await delay(500);
+    // await delay(Math.random() * 500 + 100);
+    console.warn(i);
+  });
+}

js/async-programming/parallel/parallel-limit.ts

@@ -0,0 +1,30 @@
+import { delay } from '../util/delay';
+
+type AsyncFunction = () => Promise<unknown>;
+
+const limitOf = (max: number) => {
+  const mq: AsyncFunction[] = [];
+  let count = 0;
+
+  const runTask = async (fn: AsyncFunction) => {
+    count++;
+    await fn();
+    count--;
+    if (mq.length) runTask(mq.shift()!);
+  };
+
+  return (fn: AsyncFunction) => {
+    count < max ? runTask(fn) : mq.push(fn);
+  };
+};
+
+// * ================================================================================
+
+const limit = limitOf(2);
+
+for (let i = 1; i < 10; i++) {
+  limit(async () => {
+    await delay(500);
+    console.warn(i);
+  });
+}

js/async-programming/single-lock/key-lock.ts

@@ -0,0 +1,47 @@
+// * 也可以改成 Map<string, Promise<void>[]>，数组的形式，当最后一个任务完成后（manualRes 调用时）删除 key，以便节约内存
+const chainMap = new Map<string, Promise<void>>();
+
+const keyLock = async (key: string) => {
+  if (!chainMap.get(key)) chainMap.set(key, Promise.resolve());
+  const chain = chainMap.get(key)!;
+
+  let prevPromise = chain;
+
+  // * 将 resolve 提到外部，以便实现手动触发
+  let waitingRes: Function;
+  let nextPromise = new Promise<void>((res) => {
+    waitingRes = res;
+  });
+
+  chainMap.set(
+    key,
+    chain.then(() => nextPromise),
+  );
+
+  await prevPromise;
+
+  return waitingRes!;
+};
+
+// * ================================================================================
+
+import { delay } from '../util/delay';
+
+async function process(key: string, msg?: string) {
+  let release = await keyLock(key);
+  console.log('get locker', key, msg);
+
+  await delay(1000);
+
+  console.log('end locker', key, msg);
+  release();
+}
+
+process('key1', 'dog');
+process('key1', 'cat');
+process('key2', 'Macbook');
+// process('key3', 'JavaScript');
+// process('key3', 'TypeScript');
+// process('key3', 'ClojureScript');
+// process('key3', 'Rust');
+// process('key3', 'Haskell');

js/async-programming/single-lock/single-lock.ts

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+// * 也可以做成高阶函数，以便生成多个 lock 独立运作
+
+let chain = Promise.resolve();
+
+export const singleLock = async () => {
+  let prevPromise = chain;
+
+  // * 将 resolve 提到外部，以便实现手动触发
+  let manualRes: Function;
+  let nextPromise = new Promise<void>((res) => {
+    manualRes = res;
+  });
+
+  chain = chain.then(() => nextPromise);
+
+  await prevPromise;
+
+  return manualRes!;
+};
+
+// * ================================================================================
+
+import { delay } from '../util/delay';
+
+async function process(msg: string) {
+  let release = await singleLock();
+  console.log('get locker', msg);
+
+  await delay(1000);
+
+  console.log('end locker', msg);
+  release();
+}
+
+process('JavaScript');
+process('TypeScript');
+process('ClojureScript');
+process('Rust');
+process('Haskell');

js/async-programming/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "CommonJS",
+    "esModuleInterop": true,
+    "moduleResolution": "node",
+    "allowSyntheticDefaultImports": true,
+    "strict": true,
+    "allowJs": true
+  },
+}

js/async-programming/util/delay.ts

@@ -0,0 +1 @@
+export const delay = (ms: number = 100) => new Promise((res) => setTimeout(res, ms));