What Occurs When You Run Rails dev:cache Command?

The rails dev:cache command toggles caching in improvement.

By default, Rails allows caching solely in manufacturing surroundings. To allow it within the improvement mode, you’ll be able to run rails dev:cache command. To disable it, re-run the command.

$ bin/rails dev:cache
Improvement mode is now being cached.

$ bin/rails dev:cache
Improvement mode is not being cached.

Behind the scenes, it is carried out as a Thor command that delegates to the Rails::DevCaching module.

# railties/lib/rails/instructions/dev/dev_command.rb

require "rails/dev_caching"

module Rails
  module Command
    class DevCommand < Base
      desc "cache", "Toggle improvement mode caching on/off"
      def cache
        Rails::DevCaching.enable_by_file
      finish
    finish
  finish
finish

The DevCaching::enable_by_file methodology does the next:

1. Create a tmp listing if it does not exist.
2. If the caching file (named caching-dev.txt) is current contained in the tmp listing, it means caching is enabled. Delete that file to disable it. In any other case, create it to allow caching.
3. Lastly, contact the restart.txt file to instruct Rails to restart the app.

# railties/lib/rails/dev_caching.rb

require "fileutils"

module Rails
  module DevCaching
    class << self
      FILE = "tmp/caching-dev.txt"

      def enable_by_file
        FileUtils.mkdir_p("tmp")

        if File.exist?(FILE)
          delete_cache_file
          places "Improvement mode is not being cached."
        else
          create_cache_file
          places "Improvement mode is now being cached."
        finish

        FileUtils.contact "tmp/restart.txt"
      finish
    finish
  finish
finish

How Rails Makes use of the Caching File?

When your Rails utility begins, it checks for the presence of the caching file above, and if it exists, it does the next:

1. Allow perform_caching and enable_fragment_cache_logging on the controller.
2. Set the cache retailer to :memory_store.
3. Add the Cache-Management header to public with max-age set to 2 days.

In any other case, it disables caching and makes use of the :null_store.

# config/environments/improvement.rb

if Rails.root.be part of("tmp/caching-dev.txt").exist?
  config.action_controller.perform_caching = true
  config.action_controller.enable_fragment_cache_logging = true

  config.cache_store = :memory_store
  config.public_file_server.headers = {
    "Cache-Management" => "public, max-age=#{2.days.to_i}"
  }
else
  config.action_controller.perform_caching = false

  config.cache_store = :null_store
finish

• perform_caching configures whether or not the appliance ought to carry out the caching options offered by Motion Controller or not.
• enable_fragment_cache_logging determines whether or not to log fragment cache reads and writes in a verbose format.
• cache_store configures which cache retailer to make use of for Rails caching.

The above settings instruct Rails to carry out caching. The way it implements it, properly, that is a subject for one more weblog publish. Keep tuned.

That is a wrap. I hope you favored this text and also you discovered one thing new.

As at all times, when you have any questions or suggestions, did not perceive one thing, or discovered a mistake, please go away a remark beneath or ship me an e-mail. I reply to all emails I get from builders, and I sit up for listening to from you.

If you would like to obtain future articles straight in your e-mail, please subscribe to my weblog. For those who’re already a subscriber, thanks.

Be part of our e-newsletter

Subscribe to get the brand new posts by way of e-mail. Your e-mail tackle is rarely offered or shared.