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✏️ Editing: stale-contention.js

var fs = require('fs')
var lockFile = require('../')
var test = require('tap').test
var path = require('path')
var lock = path.resolve(__dirname, 'stale.lock')
var touch = require('touch')
var spawn = require('child_process').spawn
var node = process.execPath

// We're using a lockfile with an artificially old date,
// so make it use that instead of ctime.
// Probably you should never do this in production!
lockFile.filetime = 'mtime'

if (process.argv[2] === 'child') {
  return child()
}

function child () {
  // Make fs.stat take 100ms to return its data
  // This is important because, in a test scenario where
  // we're statting the same exact file rapid-fire like this,
  // it'll end up being cached by the FS, and never trigger
  // the race condition we're trying to expose.
  fs.stat = function (stat) { return function () {
    var args = [].slice.call(arguments)
    var cb = args.pop()
    stat.apply(fs, args.concat(function(er, st) {
      setTimeout(function () {
        cb(er, st)
      }, 100)
    }))
  }}(fs.stat)

lockFile.lock(lock, { stale: 100000 }, function (er) {
    if (er && er.code !== 'EEXIST')
      throw er
    else if (er)
      process.exit(17)
    else
      setTimeout(function(){}, 500)
  })
}

test('create stale file', function (t) {
  try { fs.unlinkSync(lock) } catch (er) {}
  touch.sync(lock, { time: '1979-07-01T19:10:00.000Z' })
  t.end()
})

test('contenders', function (t) {
  var n = 10
  var fails = 0
  var wins = 0
  var args = [ __filename, 'child' ]
  var opt = { stdio: [0, "pipe", 2] }
  for (var i = 0; i < n; i++) {
    spawn(node, args, opt).on('close', then)
  }

function then (code) {
    if (code === 17) {
      fails ++
    } else if (code) {
      t.fail("unexpected failure", code)
      fails ++
    } else {
      wins ++
    }
    if (fails + wins === n) {
      done()
    }
  }

function done () {
    t.equal(wins, 1, "should have 1 lock winner")
    t.equal(fails, n - 1, "all others should lose")
    t.end()
  }
})

test('remove stale file', function (t) {
  try { fs.unlinkSync(lock) } catch (er) {}
  t.end()
})

MR SKB