main.js

const nethackShimCallback = require("./src/nethackCallback");
const crl = require("./index");
const {init, Log} = crl;
let nethackInternalLogger;
let runCount = 0;
/* global WebAssembly */

// this returns an Object containing the emscription Module options
// the NetHack emscripten implementation adds lots of state information
// to the Object, so we have to build a new one each time we want to run
// NetHack
function buildWasmModule() {
    let {info, warn} = nethackInternalLogger;
    return {
        // undocumented callback function that is run when the emscripten program completes
        quit: function(errorCode) {
            console.info(`NetHack run # ${runCount} completed with status: ${errorCode}`);
            printTimer();
            // run NetHack in an infinite loop
            startNethack();
        },
        logReadFiles: true,
        // noExitRuntime: false,
        // noInitialRun: false,
        print: info,
        printErr: warn,
        // print: () => {},
        // printErr: () => {},
    };
}

// start / restart NetHack
function startNethack() {
    runCount++;
    console.info(`Starting NetHack: run #${runCount}`);
    printMemory();
    let nethackStart = require("@neth4ck/neth4ck");
    setTimeout(() => {
        startTimer();
        nethackStart(nethackShimCallback, buildWasmModule());
        // XXX: must remove uncaughtException and unhandledRejection to prevent memory leak
        // See also: https://github.com/emscripten-core/emscripten/issues/12740#issuecomment-724447423
        process.removeAllListeners("uncaughtException");
        process.removeAllListeners("unhandledRejection");
        process.on("uncaughtException", function(ex) {
            console.warn("uncaughtException (but it's okay)");
            // TODO: check if message is "unreachable" and top of stack is "at nh_terminate (<anonymous>:wasm-function[974]:0x13abdd)"
            if (!(ex instanceof WebAssembly.RuntimeError)) {
                console.error("THROWING", ex);
                throw ex;
            }
        });
    }, 7000);
}

let startTime;
let startUsage;
function startTimer() {
    startUsage = process.cpuUsage();
    startTime = process.hrtime.bigint();
}

// print time since startTimer
function printTimer() {
    const NS_PER_SEC = 1e9;
    const US_PER_SEC = 1e6;

    let cpuUsage = process.cpuUsage(startUsage);
    let endTime = process.hrtime.bigint();
    let runTime = endTime - startTime;
    console.debug(`Run time: ${ns2s(runTime)}   User CPU: ${cpuUsage.user / US_PER_SEC} sec.   System CPU: ${cpuUsage.system / US_PER_SEC} sec.`);

    // nanoseconds to seconds string
    function ns2s(ns) {
        let s = BigInt(ns) / BigInt(NS_PER_SEC);
        ns = ns - (BigInt(ns) / BigInt(NS_PER_SEC));
        return `${s}.${pad(ns)} sec.`;
        // return `${s} sec.`;
    }

    function pad(num) {
        let s = `000000000${num.toString()}`;
        return s.substr(s.length - 9);
    }
}

// print memory usage
function printMemory() {
    let {rss, heapTotal, heapUsed, external, arrayBuffers} = process.memoryUsage();
    let percentHeap = (heapUsed / heapTotal) * 100;
    console.debug(`Heap Usage: ${b2s(heapUsed)} (${percentHeap.toFixed(1)}% of ${b2s(heapTotal)}) :: ArrayBuffers: ${b2s(arrayBuffers)}   External: ${b2s(external)}   [[ Total Memory (RSS): ${b2s(rss)} ]]`);

    // # bytes to string
    function b2s(b) {
        const BYTES_PER_KB = 1024;
        let size = 0;

        while (b > BYTES_PER_KB) {
            b = b / BYTES_PER_KB;
            size++;
        }

        switch (size) {
        case 0: return `${b.toFixed(2)} B`;
        case 1: return `${b.toFixed(2)} KB`;
        case 2: return `${b.toFixed(2)} MB`;
        case 3: return `${b.toFixed(2)} GB`;
        case 4: return `${b.toFixed(2)} TB`;
        default: return `${b.toFixed(2)} ??`;
        }
    }
}

module.exports = {
    // eslint-disable-next-line jsdoc/require-jsdoc
    runNethack: async function() {
        await init();
        nethackInternalLogger = new Log("nethack-internal");
        startNethack();
    },
    crl,
};