From 86aa3511bfdf148be8896fd19682a6d5fac31da3 Mon Sep 17 00:00:00 2001
From: Book Pauk <bookpauk@gmail.com>
Date: Sun, 23 Oct 2022 16:32:55 +0700
Subject: [PATCH] =?UTF-8?q?=D0=9D=D0=BE=D0=B2=D1=8B=D0=B9=20=D0=BC=D0=BE?=
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---
 server/core/HeavyCalc.js | 133 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 server/core/HeavyCalc.js

diff --git a/server/core/HeavyCalc.js b/server/core/HeavyCalc.js
new file mode 100644
index 0000000..a12f31e
--- /dev/null
+++ b/server/core/HeavyCalc.js
@@ -0,0 +1,133 @@
+const { Worker } = require('worker_threads');
+
+class CalcThread {
+    constructor() {
+        this.worker = null;
+        this.listeners = new Map();
+        this.requestId = 0;
+
+        this.runWorker();
+    }
+
+    terminate() {
+        if (this.worker) {
+            this.worker.terminate();
+
+            for (const listener of this.listeners.values()) {
+                listener({error: 'Worker terminated'});
+            }
+        }
+        this.worker = null;
+    }
+
+    runWorker() {
+        const workerProc = () => {
+            const { parentPort } = require('worker_threads');
+
+            const sleep = (ms) => {
+                return new Promise(resolve => setTimeout(resolve, ms));
+            };
+
+            if (parentPort) {
+                parentPort.on('message', async(mes) => {
+                    let result = {};
+                    try {
+                        const fn = new Function(`'use strict'; return ${mes.fn}`)();
+                        result.result = await fn(mes.args, sleep);
+                    } catch (e) {
+                        result = {error: e.message};
+                    }
+
+                    result.requestId = mes.requestId;
+                    parentPort.postMessage(result);
+                });
+            }
+        };
+
+        const worker = new Worker(`const wp = ${workerProc.toString()}; wp();`, {eval: true});
+
+        worker.on('message', (mes) => {
+            const listener = this.listeners.get(mes.requestId);
+            if (listener) {
+                this.listeners.delete(mes.requestId);
+                listener(mes);
+            }
+        });
+
+        worker.on('error', (err) => {
+            console.error(err);
+        });
+
+        worker.on('exit', () => {
+            this.terminate();
+        });
+
+        this.worker = worker;
+    }    
+
+    //async
+    run(params) {//args, fn
+        return new Promise((resolve, reject) => {
+            this.requestId++;
+
+            this.listeners.set(this.requestId, (mes) => {
+                if (mes.error)
+                    reject(new Error(mes.error));
+                else
+                    resolve(mes.result);
+            });
+
+            if (this.worker) {
+                this.worker.postMessage({requestId: this.requestId, args: params.args, fn: params.fn.toString()});
+            } else {
+                reject(new Error('Worker does not exist'));
+            }
+        });
+    }
+}
+
+class HeavyCalc {
+    constructor(opts = {}) {
+        this.threads = opts.threads || 1;
+        this.singleton = opts.singleton || false;
+        this.terminated = false;
+
+        this.workers = [];
+        this.load = [];
+        for (let i = 0; i < this.threads; i++) {
+            const worker = new CalcThread();
+            this.workers.push(worker);
+            this.load.push(0);
+        }
+    }
+
+    async run(params) {
+        if (this.terminated || !this.workers.length)
+            throw new Error('All workers terminated');
+
+        //находим поток с минимальной нагрузкой
+        let found = 0;
+        for (let i = 1; i < this.load.length; i++) {
+            if (this.load[i] < this.load[found])
+                found = i;
+        }
+
+        try {
+            this.load[found]++;
+            return await this.workers[found].run(params);
+        } finally {
+            this.load[found]--;
+        }
+    }
+
+    terminate() {
+        for (let i = 0; i < this.workers.length; i++) {
+            this.workers[i].terminate();
+        }
+        this.workers = [];
+        this.load = [];
+        this.terminated = true;
+    }
+}
+
+module.exports = HeavyCalc;
\ No newline at end of file