Expedite

Expedite is a Ruby preloader manager that allows commands to be executed against preloaded Ruby applications. Preloader applications can derive from other preloaders, allowing derivatives to start faster.

Usage

To use expedite you need to define agents and actions in an expedite_helper.rb that is placed in the root directory of your application. The sample discussed in this section is in the examples/simple folder.

Logs can be configured by adjusting the environment:

Expedite.define do
  environment do
    # Log to STDOUT
    self.log_file = STDOUT

    # Log to a file
    self.log_file = "log.txt"

    # No logs
    self.log_file = nil
  end
end

You define agents which are processes that will process the requests. You can create agents from forking other agents. In the example below, the "development/*" agents are forked from the "parent" agent.

Expedite.define do
  agent :parent do
    before(:serve) do |name|
      $parent_var = name
    end
  end

  agent "development/*" do
    self.parent = :parent

    before(:serve) do |name|
      $child_var = name
    end
  end
end

The following defines an info action.

Expedite.define do
  action :info do
    {
      "Process.pid" => Process.pid,
      "Process.ppid" => Process.ppid,
      "$parent_var" => $parent_var,
      "$child_var" => $child_var,
    }
  end
end

After defining your agents and actions, you can then use it. In the simple example, the main.rb calls the info command on the development/abc agent.

The invoke method will execute the action, and return the result. There is also an exec method that will replace the current executable with the action; in that case, the return result is the exit code.

require 'expedite'

puts Expedite.agent("development/abc").invoke("info")

When you run main.rb, the following output is produced. Note that $sleep_parent comes from teh parent agent, and $sleep_child comes from the development/abc agent.

# bundle exec ./main.rb
     Process.pid = 3855
    Process.ppid = 3854
     $parent_var = 1
$development_var = development/abc

Calling main.rb automatically started the expedite server in the background. In the above example, it does the following:

1. Launch the parent agent.
2. Fork from the parent agent to create the development/abc agent.
3. Fork from the development/abc agent to run the info command, and then quit.

To explicitly stop the server and all the agents, you use:

$ bundle exec expedite stop

You can also start the server in the foreground.

$ bundle exec expedite server

If rails is in the Gemfile, then you can also start the rails commands through expedite.

$ bundle exec expedite rails console
$ echo "puts ActiveRecord::Base.connection" | bundle exec expedite rails runner -

Acknowledgements

Expedite's server core is modified from Spring