CSE2410 Fall 2014 Bounce

  try { lockFile.unlockSync('contentious-lock') } catch (er) {}

test('lock contention', function (t) {

  var gotlocks = 0;

  var N = 200

  var delay = 10

  // allow for some time for each lock acquisition and release.

  // note that raising N higher will mean that the overhead

  // increases, because we're creating more and more watchers.

  // irl, you should never have several hundred contenders for a

  // single lock, so this situation is somewhat pathological.

  var overhead = 200

  var wait = N * overhead + delay

  // first make it locked, so that everyone has to wait

  lockFile.lock('contentious-lock', function(er, lock) {

    t.ifError(er, 'acquiring starter')

    if (er) throw er;

    t.pass('acquired starter lock')

    setTimeout(function() {

      lockFile.unlock('contentious-lock', function (er) {

        t.ifError(er, 'unlocking starter')

        if (er) throw er

        t.pass('unlocked starter')

      })

    }, delay)

  })

  for (var i=0; i < N; i++)

    lockFile.lock('contentious-lock', { wait: wait }, function(er, lock) {

      if (er) throw er;

      lockFile.unlock('contentious-lock', function(er) {

        if (er) throw er

        gotlocks++

        t.pass('locked and unlocked #' + gotlocks)

        if (gotlocks === N) {

          t.pass('got all locks')

          t.end()

        }

      })

    })

})

  try { lockFile.unlockSync('contentious-lock') } catch (er) {}