archived-nodemon/lib/config/watchable.js

var utils = require('../utils'),
    path = require('path'),
    fs = require('fs');

// Attempts to see if fs.watch will work. On some platforms, it doesn't.
// See: http://nodejs.org/api/fs.html#fs_caveats
// Sends the callback true if fs.watch will work, false if it won't
//
// Caveats:
// If there is no writable tmp directory, it will also return true, although
// a warning message will be displayed.
var changeDetected = false;

function check(cb) {
  var tmpdir;

  this.cb = cb;
  this.changeDetected = false;
  if (utils.isWindows) {
    tmpdir = process.env.TEMP;
  } else if (process.env.TMPDIR) {
    tmpdir = process.env.TMPDIR;
  } else {
    tmpdir = '/tmp';
  }
  var watchFileName = path.join(tmpdir, 'nodemonCheckFsWatch' + Date.now());
  var watchFile = fs.openSync(watchFileName, 'w');
  if (watchFile < 0) {
    util.log.fail('Unable to write to temp directory. If you experience problems with file reloading, ensure ' + tmpdir + ' is writable.');
    cb(true);
    return;
  }
  fs.watch(watchFileName, function() {
    if (changeDetected) { return; }
    changeDetected = true;
    cb(true);
  });
  // This should trigger fs.watch, if it works
  fs.writeSync(watchFile, '1');
  fs.unlinkSync(watchFileName);

  setTimeout(function() { verify(); }, 250);
};

// Verifies that fs.watch was not triggered and sends false to the callback
var verify = function() {
  if (!changeDetected) {
    cb(false);
  }
};

var watchable = module.exports = function (config, ready) {
  check(function(success) {
    config.system.watchWorks = success;
    ready();
  });
};

watchable.check = check;