fix: prevent lint all files

[ricardogobbosouza]

This PR contains a:

• bugfix
• new feature
• code refactor
• test update
• typo fix
• metadata update

Motivation / Use-Case

The goal is to group the changed files and execute lint only at the end

succeedModule its called for every file and watch mode just file changed
finishModules is called with all modules and is responsible for linting added files

Resolve #75

Breaking Changes

Additional Info

[codecov]

Codecov Report

Merging #77 (a0826cf) into master (be0391e) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #77   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            8         8           
  Lines          251       251           
  Branches        71        71           
=========================================
  Hits           251       251           

Impacted Files	Coverage Δ
src/index.js	100.00% <100.00%> (ø)

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[alexander-akait]

I think we need to look at better hook and logic here, but right now is good solution, let's return to this in future

Will be great to add test using mock

[watjurk]

I think that unfortunately this fix won't work after merging fix-cache-result-storage because files that aren't changed won't be linted:
-index.js (imports lintError.js)
-lintError.js

webpack reports errors from lintError.js
now let's change index js (still imports lintError.js)
webpack doesn't report errors from lintError.js because succeedModule in watch mode (after first run) is called only for changed files

I would suggest not merging this PR and creating global cache in linter.js and invalidating it with compiler.modifiedFiles and compiler.removedFiles.
Example implementation: https://github.com/watjurk/eslint-webpack-plugin/tree/fix-cache-result-storage

[ricardogobbosouza]

This will only be possible in v3 because compiler.modifiedFiles does not exist in webpack 4

[ricardogobbosouza]

In v3 version support for webpack 4 will be removed

[watjurk]

when v3 will be available, as beta or next ?

[watjurk]

I've learned about compiler.hooks.invalid, I think this is the solution here. I updated my implementation accordingly.

[ricardogobbosouza]

@watjurk It looks good to me 😄

[watjurk]

Should I create PR to this repo ?

[ricardogobbosouza]

Do you want to create a pr or do you prefer me to do it?

[watjurk]

I think I prefer you to do this, maybe some day...

[wendyzhaogogo]

compiler.hooks.invalid

why compiler.hooks.invalid is ok? i find it's fs.watcher.once('change')

[watjurk]

Sorry but I don't understand your point, could you explain ?

[wendyzhaogogo]

I've learned about compiler.hooks.invalid, I think this is the solution here. I updated my implementation accordingly.

I just don't known the reason, why compiler.hooks.invalid is the solution.
Will invalid be triggered when any file be deleted?

[ricardogobbosouza]

According to the documentation, the invalid hook is called to the changed or removed file
https://webpack.js.org/api/compiler-hooks/#invalid

[wendyzhaogogo]

According to the documentation, the invalid hook is called to the changed or removed file
https://webpack.js.org/api/compiler-hooks/#invalid
https://github.com/webpack/webpack/blob/fd056e27f477e364c16d1b09b39905fce28c13ca/lib/Watching.js#L252


but the source code of webpack v4 confused me

[watjurk]

Search for _done method in the Watching.js, and you will find:

process.nextTick(() => {
  if (!this.closed) {
    this.watch(
      compilation.fileDependencies,
      compilation.contextDependencies,
      compilation.missingDependencies
    );
  }
});

as you see this.watch is called every time webpack is done compiling, and this is why this.watcher.once i really "not once".

[wendyzhaogogo]

Search for _done method in the Watching.js, and you will find:

process.nextTick(() => {
  if (!this.closed) {
    this.watch(
      compilation.fileDependencies,
      compilation.contextDependencies,
      compilation.missingDependencies
    );
  }
});

as you see this.watch is called every time webpack is done compiling, and this is why this.watcher.once i really "not once".

Thank you ,so the name of this hook called 'invalid' is not strict ,is it ?

[watjurk]

What do you mean by saying it's not strict ? It's just called 'invalid' because it's called every time compilation is invalidated (something change), this is how I think about it.

[wendyzhaogogo]

What do you mean by saying it's not strict ? It's just called 'invalid' because it's called every time compilation is invalidated (something change), this is how I think about it.

yes , you are right.that's it, I have to learn webpack in detail.

[ricardogobbosouza]

This PR temporarily solves the performance problem ...
Waiting #79