fourier-ondemand/ondemand.js

const config = require("fourier-common").config;
const db = require("fourier-common").fbconn.database();
const spawn = require("child_process").spawn;
const path = require("path");
const express = require('express');
const version = require('./package.json').version;

var working = false;

var queue = {};

var od_ref = db.ref("devices").child(config.device_id).child("ondemand");

var proc;

function process_queue() {
  if (working) return;
  working = true;

  //var key = Object.keys(queue)[0];
  //if (!key) return;

  //var job = queue[key];

  //delete queue[key];
  var job = queue.shift();
  if(!job) {
    console.log("nothing left to do");
    working = false;
    return;
  }

  var key = job.key;

  if (job.status == "done" || job.status === "no_index") {
    setTimeout(() => {
      working = false;
      process_queue();
    }, 1000);
    return;
  }

  od_ref.child(key).update({status: "in_progress"});

  var params = [
    path.join(config.installDir,"fourier/process_timespan_nodb.py"),
    config.device_id,
    job.station,
    job.fromTime,
    job.toTime,
    job.ad,
    key,
  ];

  if (job.ads) params.push(job.ads.join(","));

  console.log("ondemand: " + params.join(" "));

  proc = spawn("python", params);
  proc.stdout.on("data", data => {
    console.log("ondemand data: " + data);
  });
  proc.stderr.on("data", data => {
    console.log("ondemand error: " + data);
  });
  proc.on("exit", code => {
    working = false;
    proc = null;
    if (code == 2) {
      od_ref.child(key).update({status: "no_index"});
    } else {
      od_ref.child(key).update({status: "done"});
    }
    console.log("done", key);
    process_queue();
  });
}

function addAndProc(key, job) {
    //queue[key] = job;
  queue.push(job);
  job.key = key;
  process_queue();
}

function start() {
  queue = [];

  od_ref.on("child_added", snp => {
    console.log("added", snp.key);
    addAndProc(snp.key, snp.val());
  });

  //od_ref.on("child_changed", snp => {
  //  addAndProc(snp.key, snp.val());
  //});
}

let endpoint = express();
endpoint.get('/info', function(request, response) {
  response.send(JSON.stringify({
    'version': version,
    'processID': process.id,
    'memoryUsage': process.memoryUsage().rss
  }));
});
endpoint.listen(49223);

function stop() {
  od_ref.off();
  queue = {};
}

module.exports = {
  start: start,
  stop: stop,
};