指南针手表的Ruby Guard

Question

I have the following guardfile in my .net project:

# Listen for chanes to css|js|cshtml files, copy to server_root, creating new folders as necessary
watch(%r{.+\.(css|js|cshtml?)$}) do |match|
    puts Time.now.asctime + ': '+ match[0] + ' has changed'
    copy_path = server_root + File.dirname(match[0])
    if Dir.exists?(copy_path) == false
        FileUtils.mkdir_p(copy_path)
    end
    FileUtils.cp_r(match[0], copy_path)
end


# Listen for changes to Sass files, compile to local folder
puts `compass compile --time --quiet`
guard :compass do
    watch(%r{(.*)\.s[ac]ss$})
end

What's I am noticing is that over time it get's slower and slower and causes my CPU to run to it's max. This is my first time doing this, but basically I want to watch for those types of files in my project, do a compass compile on sass, and copy any changed file to their counterparts on another project that IIS points to.

My main question is how to prevent it from causing my CPU to run hot, and are there any improvements to make this type of action more efficient?

Answer 1

From what I see you are copying files from one directory to another - while both directories are watched, and your rules match both the source directories and destination directories, which triggers changes, which triggers copying again, until all that is happening is the constant copying ...

The solution is to watch only one folder and output the files to an unwatched folder.

It's best to put all your source files into eg 'src' and set the server_root to eg 'public' and then tell guard to watch only 'src' by either:

• passing the src directory to be watched in the command line: bundle exec guard -w src

• or setting the new directories option in your Guardfile :

   directories(%w(src)) 

Another option would be to ignore the destination where you've copied files, eg in your Guardfile

    ignore([/^public\//])

so that copying files there won't trigger the copying over and over again.

You might find some useful information here: https://github.com/guard/guard/wiki/Understanding-Guard

(There are tips that show you what's happening under the hood, so you can what's exactly triggering which action).