Class: CoolCrawler::CrawlerPool

Inherits:
Object
  • Object
show all
Defined in:
lib/cool_crawler.rb

Overview

This is the class that handles the queue and async requests

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(start, max_connections, delay, max_pages = 50) ⇒ CrawlerPool

Returns a new instance of CrawlerPool.



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# File 'lib/cool_crawler.rb', line 16

def initialize(start, max_connections, delay, max_pages=50)
  @uri = URI(start)
  @max_pages = max_pages
  @site = "#{uri.scheme}://#{uri.host}"
  @max_connections = max_connections
  @delay = delay
  @visited_pages = 0
  visited[uri.path] = 1
  queue << uri.path
end

Instance Attribute Details

#callback ⇒ Object (readonly)

Returns the value of attribute callback.



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# File 'lib/cool_crawler.rb', line 27

def callback
  @callback
end

#delay ⇒ Object (readonly)

Returns the value of attribute delay.



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# File 'lib/cool_crawler.rb', line 27

def delay
  @delay
end

#max_connections ⇒ Object (readonly)

Returns the value of attribute max_connections.



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# File 'lib/cool_crawler.rb', line 27

def max_connections
  @max_connections
end

#site ⇒ Object (readonly)

Returns the value of attribute site.



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# File 'lib/cool_crawler.rb', line 27

def site
  @site
end

#uri ⇒ Object (readonly)

Returns the value of attribute uri.



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# File 'lib/cool_crawler.rb', line 27

def uri
  @uri
end

Instance Method Details

#add_to_visited(path) ⇒ Object 



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# File 'lib/cool_crawler.rb', line 102

def add_to_visited(path)
  if visited?(path)
    visited[path] += 1
  else
    visited[path] = 1
  end
end

#after(page, links, body) ⇒ Object 



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# File 'lib/cool_crawler.rb', line 40

def after(page, links, body)
  callback.call(page, links, body) unless callback.nil?
end

#enqueue(path) ⇒ Object 



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# File 'lib/cool_crawler.rb', line 114

def enqueue(path)
  unless visited.include?(path)
    queue << path
  end
end

#gather_links_uri(body, page) ⇒ Object 



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# File 'lib/cool_crawler.rb', line 75

def gather_links_uri(body, page)
  links = []
  doc = Nokogiri::HTML(body)
  doc.xpath("//a").each do |a|
    next if a["href"].nil?
    uri_a = URI(a["href"].strip.split('#')[0].sub(/\\|(\s+$)/, ""))
    begin
    links << URI.join(page, uri_a).path if (uri_a.host == uri.host || uri_a.host.nil?) && uri_a.path
    rescue
      # do nothing
    end
  end
  links
end

#queue ⇒ Object 



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# File 'lib/cool_crawler.rb', line 90

def queue
  @queue ||= Queue.new
end

#run ⇒ Object 



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# File 'lib/cool_crawler.rb', line 33

def run
  until queue.empty? || @visited_pages >= @max_pages
    send_crawlers
    sleep(delay)
  end
end

#send_crawlers ⇒ Object 



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# File 'lib/cool_crawler.rb', line 44

def send_crawlers
  pages = []
  until queue.empty? || pages.size >= max_connections || @visited_pages >= @max_pages
    pages << queue.pop
    @visited_pages += 1
  end
  Async do
    internet = Async::HTTP::Internet.new
    barrier = Async::Barrier.new

    pages.each do |page|
      barrier.async do
        response = internet.get URI.join(@site, page).to_s
        body = Nokogiri::HTML(response.read)
        body.search('//img').remove
        body.search('//style').remove
        body.search('//script').remove
        links = gather_links_uri(body.to_s, URI.join(uri, page))
        after(page, links, body.to_s)
        links.each do |link|
          enqueue(link)
          add_to_visited(link)
        end
      end
    end
    barrier.wait
  ensure
    internet&.close
  end
end

#set_callback(proc) ⇒ Object 



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# File 'lib/cool_crawler.rb', line 29

def set_callback(proc)
  @callback=proc
end

#sorted_visited ⇒ Object 



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# File 'lib/cool_crawler.rb', line 110

def sorted_visited
  visited.sort_by { |_k, v| v }
end

#sum_pages ⇒ Object 



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# File 'lib/cool_crawler.rb', line 120

def sum_pages
  sum = 0
  visited.each do |_k, v|
    sum += v
  end
  sum
end

#visited ⇒ Object 



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# File 'lib/cool_crawler.rb', line 94

def visited
  @visited ||= {}
end

#visited?(path) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/cool_crawler.rb', line 98

def visited?(path)
  visited.include?(path)
end