pi-rfid-jukebox/jukebox/child-process.js

"use strict";

// TODO: These should really be their own individual classes. Are
// there enough commonalities to warrant a base class?

const spawn = require('child_process').spawn;
const EventEmitter = require('events').EventEmitter;

module.exports.ChildProcessEmitter = class ChildProcessEmitter extends EventEmitter {
  constructor(command, logger) {
    super();

    this.logger = logger;

    var cmd = command[0],
        args = command.slice(1);

    this.childProcess = spawn(cmd, args);

    this.childProcess.on('error', function(err) {
      this.logger.error("process error", { class: this.constructor.name, name: name, err: String(err).trim() });
    });

    this.childProcess.on('close', function(code, signal) {
      this.logger.debug("process closed", { class: this.constructor.name, name: name, code: code, signal: signal });
    });

    this.childProcess.stdout.on('data', (data) => {
      var s = data.toString(), lines = s.split(/\n/g);
      for (var i = 0, l = lines.length; i < l; i++) {
        this.emit('message', lines[i]);
      }
    });

    this.childProcess.stderr.on('data', (data) => {
      this.logger.error('process stderr', { class: this.constructor.name, stderr: String(data).trim()});
    });
  }

  kill() {
    this.logger.debug("killing child process");
    this.childProcess.kill();
  }

  send(message) {
    this.childProcess.stdin.write(message);
  }
}

// vim:set ts=2 sw=2 et: