worktank/dist/worker/index.js

A simple isomorphic library for executing functions inside WebWorkers or Node Threads pools.

/* IMPORT */
import WorkerError from './error.js';
import WorkerFrontend from './frontend.js';
/* MAIN */
class Worker {
    /* CONSTRUCTOR */
    constructor(name, bootloader) {
        /* EVENTS API */
        this.onClose = (code) => {
            if (this.terminated)
                return;
            this.terminated = true;
            this.worker.terminate();
            this.reject(new WorkerError(this.name, `Exited with exit code ${code}`));
        };
        this.onError = (error) => {
            if (this.terminated)
                return;
            this.terminated = true;
            this.worker.terminate();
            this.reject(error);
        };
        this.onMessage = (message) => {
            if (this.terminated)
                return;
            if (message.type === 'log') {
                this.onMessageLog(message);
            }
            else if (message.type === 'ready') {
                this.onMessageReady(message);
            }
            else if (message.type === 'result') {
                this.onMessageResult(message);
            }
        };
        this.onMessageLog = (message) => {
            console.log(message.value);
        };
        this.onMessageReady = (message) => {
            this.ready = true;
            this.tick();
        };
        this.onMessageResult = (message) => {
            if ('value' in message) { // Success
                this.resolve(message.value);
            }
            else { // Error
                const error = Object.assign(new Error(), message.error);
                this.reject(error);
            }
        };
        /* API */
        this.exec = (task) => {
            if (this.terminated)
                throw new WorkerError(this.name, 'Terminated');
            if (this.task || this.busy)
                throw new WorkerError(this.name, 'Busy');
            this.task = task;
            this.tick();
        };
        this.reject = (error) => {
            const { task } = this;
            if (!task)
                return;
            this.busy = false;
            this.task = undefined;
            this.timestamp = Date.now();
            task.reject(error);
        };
        this.resolve = (value) => {
            const { task } = this;
            if (!task)
                return;
            this.busy = false;
            this.task = undefined;
            this.timestamp = Date.now();
            task.resolve(value);
        };
        this.terminate = () => {
            if (this.terminated)
                return;
            this.terminated = true;
            this.worker.terminate();
            this.reject(new WorkerError(this.name, 'Terminated'));
        };
        this.tick = () => {
            if (this.terminated || !this.ready || !this.task || this.busy)
                return;
            this.busy = true;
            try {
                const { method, args, transfer } = this.task;
                this.worker.send({ type: 'exec', method, args }, transfer);
            }
            catch {
                this.reject(new WorkerError(this.name, 'Failed to send message'));
            }
        };
        this.busy = false;
        this.ready = false;
        this.terminated = false;
        this.timestamp = Date.now();
        this.name = name;
        this.bootloader = bootloader;
        this.worker = new WorkerFrontend(this.name, this.bootloader, this.onClose, this.onError, this.onMessage);
    }
}
/* EXPORT */
export default Worker;