cfx-server-data/resources/[system]/[builders]/webpack/webpack_builder.js

const fs = require('fs');
const path = require('path');
const workerFarm = require('worker-farm');
const async = require('async');
let buildingInProgress = false;
let currentBuildingModule = '';

// some modules will not like the custom stack trace logic
const ops = Error.prepareStackTrace;
Error.prepareStackTrace = undefined;

const webpackBuildTask = {
    shouldBuild(resourceName) {
        const numMetaData = GetNumResourceMetadata(resourceName, 'webpack_config');

        if (numMetaData > 0) {
            for (let i = 0; i < numMetaData; i++) {
                const configName = GetResourceMetadata(resourceName, 'webpack_config');

                if (shouldBuild(configName)) {
                    return true;
                }
            }
        }

        return false;

        function loadCache(config) {
            const cachePath = `cache/${resourceName}/${config.replace(/\//g, '_')}.json`;

            try {
                return JSON.parse(fs.readFileSync(cachePath, {encoding: 'utf8'}));
            } catch {
                return null;
            }
        }

        function shouldBuild(config) {
            const cache = loadCache(config);

            if (!cache) {
                return true;
            }

            for (const file of cache) {
                const stats = getStat(file.name);

                if (!stats ||
                    stats.mtime !== file.stats.mtime ||
                    stats.size !== file.stats.size ||
                    stats.inode !== file.stats.inode) {
                    return true;
                }
            }

            return false;
        }

        function getStat(path) {
            try {
                const stat = fs.statSync(path);

                return stat ? {
                    mtime: stat.mtimeMs,
                    size: stat.size,
                    inode: stat.ino,
                } : null;
            } catch {
                return null;
            }
        }
    },

    build(resourceName, cb) {
        let buildWebpack = async () => {
            let error = null;
            const configs = [];
            const promises = [];
            const numMetaData = GetNumResourceMetadata(resourceName, 'webpack_config');

            for (let i = 0; i < numMetaData; i++) {
                configs.push(GetResourceMetadata(resourceName, 'webpack_config', i));
            }

            for (const configName of configs) {
                const configPath = GetResourcePath(resourceName) + '/' + configName;

                const cachePath = `cache/${resourceName}/${configName.replace(/\//g, '_')}.json`;

                try {
                    fs.mkdirSync(path.dirname(cachePath));
                } catch {
                }

                const config = require(configPath);

                const workers = workerFarm(require.resolve('./webpack_runner'));

                if (config) {
                    const resourcePath = path.resolve(GetResourcePath(resourceName));

                    while (buildingInProgress) {
                        console.log(`webpack is busy: we are waiting to compile ${resourceName} (${configName})`);
                        await sleep(3000);
                    }

                    buildingInProgress = true;
                    currentBuildingModule = resourceName;

                    promises.push(new Promise((resolve, reject) => {
                        workers({
                            configPath,
                            resourcePath,
                            cachePath
                        }, (err, outp) => {
                            workerFarm.end(workers);

                            if (err) {
                                console.error(err.stack || err);
                                if (err.details) {
                                    console.error(err.details);
                                }

                                buildingInProgress = false;
                                currentBuildingModule = '';
                                currentBuildingScript = '';
                                reject("worker farm webpack errored out");
                                return;
                            }

                            if (outp.errors) {
                                for (const error of outp.errors) {
                                    console.log(error);
                                }
                                buildingInProgress = false;
                                currentBuildingModule = '';
                                currentBuildingScript = '';
                                reject("webpack got an error");
                                return;
                            }

                            console.log(`${resourceName}: built ${configName}`);

                            resolve();
                        });
                    }));
                }
            }

            try {
                await Promise.all(promises);
            } catch (e) {
                error = e.toString();
            }

            buildingInProgress = false;
            currentBuildingModule = '';

            if (error) {
                cb(false, error);
            } else cb(true);
        };
        buildWebpack().then();
    }
};

function sleep(ms) {
    return new Promise(resolve => setTimeout(resolve, ms));
}

RegisterResourceBuildTaskFactory('z_webpack', () => webpackBuildTask);