1'use strict';
2require('../common');
3const vm = require('vm');
4
5// We're testing a race condition so we just have to spin this in a loop
6// for a little while and see if it breaks. The condition being tested
7// is an `isolate->TerminateExecution()` reaching the main JS stack from
8// the timeout watchdog.
9const sandbox = { timeout: 5 };
10const context = vm.createContext(sandbox);
11const script = new vm.Script(
12  'var d = Date.now() + timeout;while (d > Date.now());',
13);
14const immediate = setImmediate(function() {
15  throw new Error('Detected vm race condition!');
16});
17
18// When this condition was first discovered this test would fail in 50ms
19// or so. A better, but still incorrect implementation would fail after
20// 100 seconds or so. If you're messing with vm timeouts you might
21// consider increasing this timeout to hammer out races.
22const giveUp = Date.now() + 5000;
23do {
24  // The loop adjusts the timeout up or down trying to hit the race
25  try {
26    script.runInContext(context, { timeout: 5 });
27    ++sandbox.timeout;
28  } catch {
29    --sandbox.timeout;
30  }
31} while (Date.now() < giveUp);
32
33clearImmediate(immediate);
34