** Invoke crawl_next (first_time)
** Invoke environment (first_time)
** Execute environment
** Execute crawl_next
rake aborted!
NoMethodError: undefined method `clear' for false:FalseClass
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/usr/local/rvm/gems/ruby-2.5.0/gems/activerecord-5.1.5/lib/active_record/transactions.rb:323:in `rollback_active_record_state!'
/usr/local/rvm/gems/ruby-2.5.0/gems/activerecord-5.1.5/lib/active_record/transactions.rb:307:in `save'
/usr/local/rvm/gems/ruby-2.5.0/gems/activerecord-5.1.5/lib/active_record/suppressor.rb:42:in `save'
/home/ubuntu/workspace/web_monitor/lib/tasks/scheduler.rake:19:in `block (2 levels) in <top (required)>'
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/usr/local/rvm/rubies/ruby-2.5.0/lib/ruby/2.5.0/monitor.rb:226:in `mon_synchronize'
/usr/local/rvm/rubies/ruby-2.5.0/lib/ruby/gems/2.5.0/gems/rake-12.3.0/lib/rake/task.rb:188:in `invoke_with_call_chain'
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Tasks: TOP => crawl_next

desc "perform crawls for active alerts if their interval has passed"
task :crawl_next => :environment do
  alerts = Alert.where(active: true).includes(:crawls)

  alerts.each do |alert|
    last = alert.crawls.last

    last_crawl_time = last.crawl_time if !last.nil?

    if last.nil? ||
       (last_crawl_time + alert.crawl_interval_mins*60) < Time.now + 1
      crawl_stats = alert.crawl
    end

    if crawl_stats
      crawl = Crawl.new(crawl_stats)
      crawl.save

      if crawl.exceeds_limits? || crawl.errors
        UserMailer.crawl_alert(alert, crawl).deliver_later
      end
    else
      alert.deactivate
    end
  end
end

class Crawl < ActiveRecord::Base
  belongs_to :alert

  after_save :update_alert_last_crawl

  def update_alert_last_crawl
    alert = self.alert
    alert.update(last_crawl: self.crawl_time)
  end

  def exceeds_limits?
    self.resp_time_ms > self.alert.response_time_threshold_ms
  end

  def errors
    self.resp_code != "200"
  end
end

class Alert < ActiveRecord::Base
  has_many :user_alerts
  has_many :users, through: :user_alerts, dependent: :destroy
  has_many :crawls, dependent: :destroy

  before_save :activate # TODO: don't activate all alerts before save

  validate :valid_url? # Using custom method instead of valid url gem

  validates :crawl_interval_mins, presence: true, inclusion: {in: [10, 30, 60]}
  validates :notify_emails, presence: true, length: {minimum: 6}
  validates :name, presence: true, length: {minimum: 2}

  def activate
    self.active = true
  end

  def deactivate
    self.active = false
    UserMailer.alert_deactivated(self).deliver_later
  end

  # Return a hash corresponding to a Crawl's schema, to be used in creating
  # a new crawl record
  def crawl
    data = {}
    resp = nil

    time = Benchmark.measure do
      begin
        resp = HTTParty.get(self.url)
      rescue => e
        data = crawl_error_info(e)
      end
    end

    {
      alert_id: self.id,
      crawl_time: Time.now.to_s,
      resp_code: data[:resp_code] || resp.code,
      resp_time_ms: data[:resp_time_ms] || time.real * 1_000,
      resp_status: data[:resp_status] || resp.message,
      resp_size_kb: data[:resp_size_kb] || resp.size # TODO: convert to mb
    }
  end

  def valid_url?
    if !self.url.match(/^(((http|https)://|)?[a-z0-9]+([-.]{1}[a-z0-9]+)*.[a-z]{2,6}(:[0-9]{1,5})?(/.*)?)$/i)
      errors.add(:url, "not valid")
    end
  end

  def crawl_error_info(e)
    if e.class == SocketError
      return {
        resp_code: 443,
        resp_time_ms: 0,
        resp_status: "NAME/SVC NOT KNOWN",
        resp_size_kb: 0 # TODO: convert to mb
      }
    end
  end
end