testarmada-magellan/src/util/port_util.js

Massively parallel automated testing

/* eslint operator-assignment: 0 */
"use strict";

const settings = require("../settings");
const checkPorts = require("./check_ports");

const MAX_ACQUIRE_ATTEMPTS = 100;
const MAX_PORT = settings.BASE_PORT_START + settings.BASE_PORT_RANGE - 1;
let portCursor;

const util = {

  // Return magellan's internal port cursor, i.e. the next port that can potentially
  // be probed for availability. This doesn't perform a port contention check. Calling
  // this function also ticks the port cursor upwards regardless of result.
  getNextPort: () => {
    // Reset back to start of range
    if (typeof portCursor === "undefined" || portCursor + settings.BASE_PORT_SPACING > MAX_PORT) {
      portCursor = settings.BASE_PORT_START;
    }

    // Choose the next port
    const nextPort = portCursor;

    // Allocate the port for the next worker -- or spill over the range
    portCursor = portCursor + settings.BASE_PORT_SPACING;
    return nextPort;
  },

  // Call callback(err, foundPort) with either:
  //
  // 1) an Error object, if we couldnt' find a port
  // 2) null and a foundPort as the second argument
  acquirePort: (callback) => {
    let attempts = 0;

    const acquire = () => {
      // check all the ports in the range. If fail, move to next set
      const startPort = util.getNextPort();
      const ports = [];
      for (let i = startPort; i < startPort + settings.BASE_PORT_SPACING; i++) {
        ports.push(i);
      }
      checkPorts(ports, (result) => {
        let available = true;
        for (let i = 0; i < result.length; i++) {
          if (!result[i].available) {
            available = false;
            break;
          }
        }
        if (available) {
          return callback(null, result[0].port);
        } else {
          attempts++;
          if (attempts > MAX_ACQUIRE_ATTEMPTS) {
            return callback(new Error("Gave up looking for an available port after "
              + MAX_ACQUIRE_ATTEMPTS + " attempts."));
          } else {
            acquire();
          }
        }
      });
    };

    acquire();
  },

  checkPorts
};

module.exports = util;