Multithreaded Ruby "git pull".

pull.rb

#!/usr/bin/env ruby

require 'pathname'
require 'open3'

# Mass-pull git repositories.
#
#   GitPull.mass_pull(Dir.pwd)
class GitPull
  # Check for this string in directory names.
  GIT_DIR = '.git'

  # Recursively crawl down the +directory+ and +git pull+ it if it's
  # a Git repo. Shortcut method for creating an instance.
  #
  # @param directory [String, Pathname]
  def self.mass_pull(directory)
    new.mass_pull(Pathname.new(directory))
  end

  # Setup threads array.
  def initialize
    @threads = []
  end

  # Recursively crawl down the +directory+ and +git pull+ it if it's
  # a Git repo. Waits for all threads to finish.
  #
  # @param directory [Pathname]
  def mass_pull(directory)
    crawl(directory)
    @threads.each(&:join)
  end

  # Recursively crawl down the +directory+ and +git pull+ it if it's
  # a Git repo. Adds threads and does not wait.
  #
  # @param directory [Pathname]
  def crawl(directory)
    subdirectories = list_directories(directory)

    if git?(subdirectories)
      @threads << Thread.new do
        pull(directory)
      end
    else
      subdirectories.each do |subdirectory|
        crawl(subdirectory)
      end
    end
  end

  # List all relevant subdirectories in +directory+.
  #
  # @param directory [Pathname]
  def list_directories(directory)
    directory.children.select(&:directory?)
  end

  # Is there a +.git+ directory among the subdirectories?
  #
  # @param subdirectories [Array<Pathname>]
  #
  # @return [Bool]
  def git?(subdirectories)
    subdirectories.find do |directory|
      directory_name = directory.basename.to_s
      directory_name == GIT_DIR
    end
  end

  # Create a new process which updates the repository.
  # Process is needed because +Dir.chdir+ is not thread-safe.
  def pull(directory)
    command = "cd #{ directory } && git pull"
    puts command
    out, _ = Open3.capture2(command)
    puts out
  end
end

# Do it!
GitPull.mass_pull(Dir.pwd)