Reset current compilation if file was changed

[sanex3339]

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• Operating System: Mac OS 10.12.4
• Node Version: 8.11.2
• NPM Version: 5.6.0
• webpack version: 4.29.3
• webpack-dev-middleware Version: 3.5.2

• [] This is a feature request
• [x] This is a bug

Expected Behavior

Current active compilation should reset if file was changed and next compilation should start immediate

Actual Behavior

Current active compilation will finish first if file was changed and only after that - next compilation will start

For Bugs; How can we reproduce the behavior?

I'm using latest koa-webpack + webpack@4. Start server, change file, after two seconds change file again. As result - two full compilations instead of 2 seconds of first compilation + full second compilation.

[alexander-akait]

Looks problem on koa-webpack side, we don't officially support koa, i recommend use webpack-dev-server. Anyway please create minimum reproducible test repo and describe in readme what you have and what you expect.

[sanex3339]

I looked at sources https://github.com/webpack/webpack-dev-middleware/blob/master/lib/context.js#L95

context.compiler.hooks.invalid.tap('WebpackDevMiddleware', invalid);
  context.compiler.hooks.run.tap('WebpackDevMiddleware', invalid);
  context.compiler.hooks.done.tap('WebpackDevMiddleware', done);
  context.compiler.hooks.watchRun.tap('WebpackDevMiddleware', (comp, callback) => {
    invalid(callback);
  });

None of this hooks was triggered when i changed file during existing compilation process

[alexander-akait]

@sanex3339 no problem with webpack-dev-server, please create minimum reproducible test repo

[alexander-akait]

Here solution https://github.com/webpack/webpack-dev-server/issues/1479#issuecomment-442492922