Приклади фонових задач Rails з реальних додатків

Rails застосунки можуть виконувати більшу частину своєї роботи у вигляді фонових задач.

Виконання завдань в фоні дозволяє:

• прискорити час відгуку сторінки,
• пришвидшити виконання повільних завдань, які можуть призвести до таймауту, якщо вони виконуються під час запиту сервера HTTP,
• покращити відмовостійкість (фонові завдання, як правило, виконуються повторно, якщо попередня спроба виявилася невдалою).

Набір прикладів фонових задач із реальних додатків, які допоможуть вам розібратися та навчитися.

Масова розсилка листів:

class SendAnalyticsEmailJob < ActiveJob::Base
  def perform
    Group.with_analytics.find_each do |group|
      BaseMailer.send_bulk_mail(to: group.admins) do |user|
        UserMailer.delay(priority: 10).analytics(user: user, group: group)
      end
    end
  end
end

Джерело

Генерація PDF

class PdfGenerationJob < ActiveJob::Base
  queue_as :pdf_generation

  def perform(claim)
    Rails.logger.info "Starting PdfGenerationJob"
    claim.generate_pdf!
    Rails.logger.info "Finished PdfGenerationJob"
  end
end

Джерело

Оновлення Database Counts

class PetitionCountJob < ActiveJob::Base
  class InvalidSignatureCounts < RuntimeError; end

  queue_as :high_priority

  def perform
    petitions = Petition.with_invalid_signature_counts

    unless petitions.empty?
      petitions.each(&:update_signature_count!)

      Appsignal.send_exception(exception(petitions))
    end
  end

  private

  def exception(petitions)
    InvalidSignatureCounts.new(error_message(petitions))
  end

  def error_message(petitions)
    I18n.t(
      :"invalid_signature_counts",
        scope:  :"petitions.errors",
        count:  petitions.size,
        ids:    petitions.map(&:id).inspect,
        id:     petitions.first.id.to_s
    )
  end
end

Джерело

Geocode

class GeocodeJob < ActiveJob::Base
  def perform(location)
    address = [location.address, location.zipcode].join(" ")

    latitude, longitude = Geocoder.coordinates(address)

    location.update!(latitude: latitude, longitude: longitude)
  end
end

Джерело

Імпорт RSS-каналів

class FeedImporter
  include Sidekiq::Worker
  sidekiq_options queue: :critical, retry: false

  def perform(import_item_id)
    import_item = ImportItem.find(import_item_id)
    user = import_item.import.user

    finder = FeedFinder.new(import_item.details[:xml_url])
    if finder.options.any?
      feed = finder.create_feed(finder.options.first)
      if feed
        subscription = user.subscriptions.find_or_create_by(feed: feed)
        if import_item.details[:title] && subscription
          subscription.update(title: import_item.details[:title])
        end
        if import_item.details[:tag]
          feed.tag(import_item.details[:tag], user, false)
        end
      end
    end
  rescue ActiveRecord::RecordNotFound
  end

end

Джерело

Очищення даних

class CleanupEvents < ApplicationJob
  def perform
    Event::Base.transaction do
      Event::Base.where(project_logged: true, mails_sent: true, queued: true, undone_jobs: 0).lock(true).delete_all
    end
  end
end

Джерело

Підписка на розсилку

class UserSubscribeJob < ApplicationJob
  queue_as :default

  def perform(name, email)
    MailChimpService.user_subscribe(name, email)
  end
end

Джерело

Відписка від розсилки

class UserUnsubscribeJob < ApplicationJob
  queue_as :default

  def perform(email)
    MailChimpService.user_unsubscribe(email)
  end
end

Джерело

Отримання даних API

class GithubRepoFetcherJob < ApplicationJob
  queue_as :http_request

  def perform(user_id)
    User.fetch_github_repositories(user_id)
  end
end

Джерело

Оновлення пошукових індексів

class SearchIndexer < ApplicationJob
  queue_as :search_indexer

  def perform(operation, type, id)
    obj = nil
    type.downcase!

    case type
    when "topic"
      obj = Topic.find_by_id(id)
    when "page"
      obj = Page.find_by_id(id)
    when "user"
      obj = User.find_by_id(id)
    end

    return false unless obj

    if operation == "update"
      obj.__elasticsearch__.update_document
    elsif operation == "delete"
      obj.__elasticsearch__.delete_document
    elsif operation == "index"
      obj.__elasticsearch__.index_document
    end
  end
end

Джерело

Надсилання Push-сповіщень на пристрої

class PushJob < ApplicationJob
  queue_as :notifications

  # user_ids: 用户编号列表
  # note: { alert: 'Hello APNS World!', sound: 'true', badge: 1 }
  def perform(user_ids, note = {})
    return false if Setting.apns_pem.blank?

    note[:sound] ||= "true"
    devices = Device.where(user_id: user_ids).all.to_a
    devices.reject! { |d| !d.alive? }
    tokens = devices.collect(&:token)
    return false if tokens.blank?

    notification = RubyPushNotifications::APNS::APNSNotification.new(tokens, aps: note)
    pusher = RubyPushNotifications::APNS::APNSPusher.new(Setting.apns_pem, !Rails.env.production?)
    pusher.push [notification]
    Rails.logger.tagged("PushJob") do
      Rails.logger.info "send to #{tokens.size} devices #{note} status: #{notification.success}"
    end
    notification.success
  end
end

Джерело

Експорт даних CSV

# frozen_string_literal: true
require 'csv'

class CsvExportJob < ActiveJob::Base
  queue_as :csv_jobs

  def perform(csv_export)
    ActiveRecord::Base.connection_pool.with_connection do
      create_export_folder(csv_export)
      generate_csv(csv_export)
      cleanup_downloaded
    end
  end

  private

  def cleanup_downloaded
    CsvExport.old.find_each(&:destroy!)
  end

  def generate_csv(csv_export)
    csv_export.status! :started
    remove_deleted_scope_and_create_report(csv_export)
    CsvMailer.created(csv_export).deliver_now if csv_export.email.present?
    csv_export.status! :finished
    Rails.logger.info("Export #{csv_export.download_name} completed")
  rescue Errno::EACCES, IOError, ActiveRecord::ActiveRecordError => e
    csv_export.delete_file
    csv_export.status! :failed
    Rails.logger.error("Export #{csv_export.id} failed with error #{e}")
    Airbrake.notify(e, error_message: "Export #{csv_export.id} failed.")
  end

  # Helper method to removes the default soft_deletion scope for these models for the report
  def remove_deleted_scope_and_create_report(csv_export)
    Deploy.with_deleted do
      Stage.with_deleted do
        Project.with_deleted do
          DeployGroup.with_deleted do
            Environment.with_deleted do
              deploy_csv_export(csv_export)
            end
          end
        end
      end
    end
  end

  def deploy_csv_export(csv_export)
    filename = csv_export.path_file
    filter = csv_export.filters

    deploys = filter_deploys(filter)
    summary = ["-", "Generated At", csv_export.updated_at, "Deploys", deploys.count.to_s]
    filters_applied = ["-", "Filters", filter.to_json]

    CSV.open(filename, 'w+') do |csv|
      csv << Deploy.csv_header
      deploys.find_each do |deploy|
        csv << deploy.csv_line
      end
      csv << summary
      csv << filters_applied
    end
  end

  def filter_deploys(filter)
    if filter.keys.include?('environments.production')
      production_value = filter.delete('environments.production')
      # To match logic of stages.production? True when any deploy_group environment is true or
      # deploy_groups environment is empty and stages is true
      production_query = if production_value
        "(StageProd.production = ? OR (StageProd.production IS NULL AND stages.production = ?))"
      else
        "(NOT StageProd.production = ? OR (StageProd.production IS NULL AND NOT stages.production = ?))"
      end

      # This subquery extracts the distinct pairs of stage.id to environment.production for the join below as StageProd
      stage_prod_subquery = "(SELECT DISTINCT deploy_groups_stages.stage_id, environments.production "\\
      "FROM deploy_groups_stages " \\
      "INNER JOIN deploy_groups ON deploy_groups.id = deploy_groups_stages.deploy_group_id " \\
      "INNER JOIN environments ON environments.id = deploy_groups.environment_id) StageProd"

      # The query could result in duplicate entries when a stage has a production and non-production deploy group
      # so it is important this is run only if environments.production was set
      Deploy.includes(:buddy, job: :user, stage: :project).joins(:job, :stage).
        joins("LEFT JOIN #{stage_prod_subquery} ON StageProd.stage_id = stages.id").
        where(filter).where(production_query, true, true)
    else
      Deploy.includes(:buddy, job: :user, stage: :project).joins(:job, :stage).where(filter)
    end
  end

  def create_export_folder(csv_export)
    FileUtils.mkdir_p(File.dirname(csv_export.path_file))
  end
end

Джерело

Генерація та надсилання електронною поштою Kindle Ebooks

class SendToKindle
  include Sidekiq::Worker
  sidekiq_options queue: :critical
  SUPPORTED_IMAGES = %w{.jpg .jpeg .gif .png .bmp}

  def perform(entry_id, kindle_address)
    if ENV["KINDLEGEN_PATH"].blank?
      Rails.logger.error { 'Missing ENV["KINDLEGEN_PATH"]' }
    else
      send_to_kindle(entry_id, kindle_address)
    end
  end

  def send_to_kindle(entry_id, kindle_address)
    @entry = Entry.find(entry_id)
    @working_directory = Dir.mktmpdir
    begin
      content_path = write_html
      mobi_path = kindlegen(content_path)
      if File.file?(mobi_path)
        UserMailer.kindle(kindle_address, mobi_path).deliver_now
      else
        # Notify user of error?
      end
    ensure
      FileUtils.remove_entry(@working_directory)
    end
  end

  def kindlegen(content_path)
    mobi_file = 'kindle.mobi'
    system("#{ENV["KINDLEGEN_PATH"]} #{content_path} -o #{mobi_file} > /dev/null")
    File.join(@working_directory, mobi_file)
  end

  def download_image(url, destination)
    File.open(destination, "wb") do |file|
      file.write(HTTParty.get(url, {timeout: 20}).parsed_response)
    end
  rescue
    false
  end

  def render_content(content)
    action_view = ActionView::Base.new()
    action_view.view_paths = ActionController::Base.view_paths
    action_view.extend(ApplicationHelper)
    action_view.render(template: "supported_sharing_services/kindle_content.html.erb", locals: {entry: @entry, content: content})
  end

  def write_html
    content = ContentFormatter.api_format(@entry.content, @entry)
    content = Nokogiri::HTML.fragment(content)
    content = prepare_images(content)
    content_path = file_destination('kindle.html')
    File.open(content_path, "w") do |file|
      file.write(render_content(content.to_xml))
    end
    content_path
  end

  def prepare_images(parsed_content)
    images = []
    parsed_content.search("img").each_with_index do |element, index|
      next if element['src'].blank?
      src = element['src'].strip
      extension = File.extname(src)
      if SUPPORTED_IMAGES.include?(extension)
        filename = index.to_s + extension
        destination = file_destination(filename)
        if download_image(src, destination)
          element['src'] = filename
        end
      else
        next
      end
    end
    parsed_content
  end

  def file_destination(filename)
    File.join(@working_directory, filename)
  end

end

Джерело

Скасування підписки на пробну версію SaaS

class TrialExpiration
  include Sidekiq::Worker
  sidekiq_options queue: :critical

  def perform
    plan = Plan.where(stripe_id: 'trial').first
    users = User.where(plan: plan, suspended: false).where('created_at < ?', Feedbin::Application.config.trial_days.days.ago)
    Subscription.where(user_id: users).update_all(active: false)
    users.update_all(suspended: true)
  end

end

Джерело

Сканування та обробка зображень веб-сайту

require 'rmagick'
class FaviconFetcher
  include Sidekiq::Worker
  sidekiq_options retry: false

  def perform(host, force = false)
    @favicon = Favicon.unscoped.where(host: host).first_or_initialize
    @force = force
    update if should_update?
  rescue
    Librato.increment('favicon.failed')
  end

  def update
    data = nil
    favicon_found = false
    response = nil

    favicon_url = find_favicon_link
    if favicon_url
      response = download_favicon(favicon_url)
      favicon_found = true if !response.to_s.empty?
    end

    if !favicon_found
      favicon_url = default_favicon_location
      response = download_favicon(favicon_url)
    end

    if response
      processor = FaviconProcessor.new(response.to_s, @favicon.host)
      if processor.valid? && @favicon.data["favicon_hash"] != processor.favicon_hash
        @favicon.favicon = processor.encoded_favicon if processor.encoded_favicon
        @favicon.url = processor.favicon_url if processor.favicon_url
        @favicon.data = get_data(response, processor.favicon_hash)
        Librato.increment('favicon.updated')
      end
      Librato.increment('favicon.status', source: response.code)
    end

    @favicon.save
  end

  def get_data(response, favicon_hash)
    data = {favicon_hash: favicon_hash}
    if response
      data = data.merge!(response.headers.to_h.extract!("Last-Modified", "Etag"))
    end
    data
  end

  def find_favicon_link
    favicon_url = nil
    url = URI::HTTP.build(host: @favicon.host)
    response = HTTP
      .timeout(:global, write: 5, connect: 5, read: 5)
      .follow()
      .get(url)
      .to_s
    html = Nokogiri::HTML(response)
    favicon_links = html.search(xpath)
    if favicon_links.present?
      favicon_url = favicon_links.last.to_s
      favicon_url = URI.parse(favicon_url)
      favicon_url.scheme = 'http'
      if !favicon_url.host
        favicon_url = URI::HTTP.build(scheme: 'http', host: @favicon.host)
        favicon_url = favicon_url.merge(favicon_links.last.to_s)
      end
    end
    favicon_url
  rescue
    nil
  end

  def default_favicon_location
    URI::HTTP.build(host: @favicon.host, path: "/favicon.ico")
  end

  def download_favicon(url)
    response = HTTP
      .timeout(:global, write: 5, connect: 5, read: 5)
      .follow()
      .headers(request_headers)
      .get(url)
  end

  def request_headers
    headers = {user_agent: "Mozilla/5.0"}
    if !@force
      conditional_headers = ConditionalHTTP.new(@favicon.data["Etag"], @favicon.data["Last-Modified"])
      headers = headers.merge(conditional_headers.to_h)
    end
    headers
  end

  def should_update?
    if @force
      true
    else
      !updated_recently?
    end
  end

  def updated_recently?
    if @favicon.updated_at
      @favicon.updated_at > 1.hour.ago
    else
      false
    end
  end

  def xpath
    icon_names = ["icon", "shortcut icon"]
    icon_names = icon_names.map do |icon_name|
      "//link[not(@mask) and translate(@rel, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz') = '#{icon_name}']/@href"
    end
    icon_names.join(" | ")
  end

end

Джерело