install

# File lib/rubygems/request_set.rb, line 146
  def install(options, &block) # :yields: request, installer
    if dir = options[:install_dir]
      requests = install_into dir, false, options, &block
      return requests
    end

    @prerelease = options[:prerelease]

    requests = []
    download_queue = Queue.new

    # Create a thread-safe list of gems to download
    sorted_requests.each do |req|
      download_queue << req
    end

    # Create N threads in a pool, have them download all the gems
    threads = Gem.configuration.concurrent_downloads.times.map do
      # When a thread pops this item, it knows to stop running. The symbol
      # is queued here so that there will be one symbol per thread.
      download_queue << :stop

      Thread.new do
        # The pop method will block waiting for items, so the only way
        # to stop a thread from running is to provide a final item that
        # means the thread should stop.
        while req = download_queue.pop
          break if req == :stop
          req.spec.download options unless req.installed?
        end
      end
    end

    # Wait for all the downloads to finish before continuing
    threads.each(&:value)

    # Install requested gems after they have been downloaded
    sorted_requests.each do |req|
      if req.installed?
        req.spec.spec.build_extensions

        if @always_install.none? { |spec| spec == req.spec.spec }
          yield req, nil if block_given?
          next
        end
      end

      spec =
        begin
          req.spec.install options do |installer|
            yield req, installer if block_given?
          end
        rescue Gem::RuntimeRequirementNotMetError => e
          recent_match = req.spec.set.find_all(req.request).sort_by(&:version).reverse_each.find do |s|
            s = s.spec
            s.required_ruby_version.satisfied_by?(Gem.ruby_version) &&
              s.required_rubygems_version.satisfied_by?(Gem.rubygems_version) &&
              Gem::Platform.installable?(s)
          end
          if recent_match
            suggestion = "The last version of #{req.request} to support your Ruby & RubyGems was #{recent_match.version}. Try installing it with `gem install #{recent_match.name} -v #{recent_match.version}`"
            suggestion += " and then running the current command again" unless @always_install.include?(req.spec.spec)
          else
            suggestion = "There are no versions of #{req.request} compatible with your Ruby & RubyGems"
            suggestion += ". Maybe try installing an older version of the gem you're looking for?" unless @always_install.include?(req.spec.spec)
          end
          e.suggestion = suggestion
          raise
        end

      requests << spec
    end

    return requests if options[:gemdeps]

    install_hooks requests, options

    requests
  end