Perf: remove regenerate dependency

[efolio]

Hi,

Having big performance issues by only creating a tiny gulp task, I decided to investigate.

My example:

var gulp = require('gulp');
var jscs = require('gulp-jscs');

gulp.task('cs', function() {
  return gulp.src('index.js')
    .pipe(jscs())
  ;
});

The content of index.js (yes, it is a very big file):

angular.module('my-app', [])
  .factory('$i18nCache', function($cacheFactory) {
    return $cacheFactory('i18n');
  })
;

… so nothing out of the ordinary.

I time the execution. The result: 3s on my desktop machine… WTF?! O_O

So I profile the process to see what is going on. I stumble on this:

 [JavaScript]:
   ticks  total  nonlib   name
   1056   26.1%   58.3%  LazyCompile: dataAdd /home/etienne/work/glou/example/angular.app/node_modules/gulp-jscs/node_modules/jscs/node_modules/regenerate/regenerate.js:222
    262    6.5%   14.5%  Stub: KeyedLoadElementStub {1}
     92    2.3%    5.1%  RegExp: ^(\\/?|)([\\s\\S]*?)((?:\\.{1\,2}|[^\\/]+?|)(\\.[^.\\/]*|))(?:[\\/]*)$
     60    1.5%    3.3%  KeyedLoadIC: args_count: 0 {1}
     16    0.4%    0.9%  LazyCompile: Join native array.js:119
     13    0.3%    0.7%  LazyCompile: extend.add /home/etienne/work/glou/example/angular.app/node_modules/gulp-jscs/node_modules/jscs/node_modules/regenerate/regenerate.js:947
     12    0.3%    0.7%  Builtin: A builtin from the snapshot {1}
     10    0.2%    0.6%  Stub: CEntryStub
     10    0.2%    0.6%  RegExp: ^(\\/?|)([\\s\\S]*?)((?:\\.{1\,2}|[^\\/]+?|)(\\.[^.\\/]*|))(?:[\\/]*)$ {1}
      6    0.1%    0.3%  Stub: SubStringStub
      6    0.1%    0.3%  Stub: CompareICStub

etc…

1056 ticks on the library: regenerate!
58.3% of total user execution!

As I look into the only 2 rules using regenerate, maybe my understanding is wrong, but it seems that regenerate is unnecessary as the proper regexp are shipped along with unicode…

The fun thing? This tiny little patch improves the overall performance of JSCS by a factor > 200 :)

[coveralls]

Coverage increased (+0.01%) when pulling 673fdf4 on efolio:master into 5344ad7 on jscs-dev:master.

[qfox]

Wow ;-D

[mikesherov]

👏

[mdevils]

😮

[indexzero]

Awesome. Awesome to the max.

[mrjoelkemp]

LGTM. Great work. What did you use to profile the code?

[efolio]

I used node-tick-processor.

[mrjoelkemp]

Landed! Thanks again @efolio.

[AlexanderZeilmann]

Ahhh performance, thats one detail I didn't speed attention when I wrote this code a week ago.

Perhaps, monitoring the performance is something we could look into in the future...

So thanks @efolio for fixing my code :-)

[efolio]

You're welcome :)

[mathiasbynens]

For future reference, regenerate is supposed to be used as part of a build script, not at runtime!