node-fibers adapter example

gistfile1.txt

$ cat adapter.js
require('./node-fibers');
var print = require('util').print;

// This function runs an asynchronous function from within a fiber as if it
// were synchronous.
function asyncAsSync(fn /* ... */) {
  var args = [].slice.call(arguments, 1);
  var fiber = Fiber.current;

  function cb(err, ret) {
    if (err) {
      fiber.throwInto(new Error(err));
    } else {
      fiber.run(ret);
    }
  }

  // Little-known JS features: a function's `length` property is the number
  // of arguments it takes. Node convention is that the last parameter to
  // most asynchronous is a `function callback(err, ret) {}`.
  args[fn.length - 1] = cb;
  fn.apply(null, args);

  return yield();
}

var fs = require('fs');
var Buffer = require('buffer').Buffer;
Fiber(function() {
  // These are all async functions (fs.open, fs.write, fs.close) but we can
  // use them as if they're synchronous.
  print('opening /tmp/hello\n');
  var file = asyncAsSync(fs.open, '/tmp/hello', 'w');
  var buffer = new Buffer(5);
  buffer.write('hello');
  print('writing to file\n');
  asyncAsSync(fs.write, file, buffer, 0, buffer.length);
  print('closing file\n');
  asyncAsSync(fs.close, file);

  // This is a synchronous function. But note that while this function is
  // running node is totally blocking. Using `asyncAsSync` leaves node
  // available to handle more events.
  var data = fs.readFileSync('/tmp/hello');
  print('file contents: ' +data +'\n');

  // Errors made simple using the magic of exceptions
  try {
    print('deleting /tmp/hello2\n');
    asyncAsSync(fs.unlink, '/tmp/hello2');
  } catch(e) {
    print('caught this exception: ' +e.message +'\n');
  }

  // Cleanup :)
  print('deleting /tmp/hello\n');
  asyncAsSync(fs.unlink, '/tmp/hello');
}).run();
print('returning control to node event loop\n');

$ ./fiber-shim node adapter.js 
opening /tmp/hello
returning control to node event loop
writing to file
closing file
file contents: hello
deleting /tmp/hello2
caught this exception: Error: ENOENT, No such file or directory '/tmp/hello2'
deleting /tmp/hello