compare copying a file natively, and with fibers

copy.js

require('fibers');
var fs = require('fs');

function resumer() {
  var fiber = Fiber.current;
  return function(err, val) {
    if (err) {
      fiber.throwInto(err);
    } else {
      fiber.run(val);
    }
  }
}

function copyFileWithoutFiber(from, to, ondone) {
  fs.readFile(from, 'utf8', function(err, data) {
    if (err) {
      ondone(err);
      return;
    }
    fs.writeFile(to, data, 'utf8', function(err, data) {
      if (err) {
        ondone(err);
      } else {
        ondone();
      }
    });
  });
}

function copyFileWithFiber(from, to, ondone) {
  Fiber(function() {
    try {
      fs.readFile(from, 'utf8', resumer());
      var data = yield();
      fs.writeFile(to, data, 'utf8', resumer());
      yield();
      ondone();
    } catch (ex) {
      ondone(ex);
    }
  }).run();
}

copyFileWithoutFiber('srtsratscopy.js', 'honk.js', function(err) {
  console.log('done(' + err + ')');
});