101 lines
2.9 KiB
Ruby
101 lines
2.9 KiB
Ruby
require 'open-uri'
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require 'nokogiri'
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require 'excon'
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module Jobs
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class CrawlTopicLink < Jobs::Base
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class ReadEnough < Exception; end
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# Retrieve a header regardless of case sensitivity
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def self.header_for(head, name)
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header = head.headers.detect do |k, v|
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name == k.downcase
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end
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header[1] if header
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end
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def self.request_headers(uri)
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{ "User-Agent" => "Mozilla/5.0 (Windows NT 6.2; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/32.0.1667.0 Safari/537.36",
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"Accept" => "text/html",
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"Host" => uri.host }
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end
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# Follow any redirects that might exist
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def self.final_uri(url, limit=5)
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return if limit < 0
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uri = URI(url)
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return if uri.blank? || uri.host.blank?
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headers = CrawlTopicLink.request_headers(uri)
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head = Excon.head(url, read_timeout: 20, headers: headers)
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if head.status == 200
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uri = nil unless header_for(head, 'content-type') =~ /text\/html/
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return uri
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end
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location = header_for(head, 'location')
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if location
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location = "#{uri.scheme}://#{uri.host}#{location}" if location[0] == "/"
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return final_uri(location, limit - 1)
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end
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nil
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end
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# Fetch the beginning of a HTML document at a url
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def self.fetch_beginning(url)
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# Never crawl in test mode
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return if Rails.env.test?
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uri = final_uri(url)
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return "" unless uri
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result = ""
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streamer = lambda do |chunk, remaining_bytes, total_bytes|
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result << chunk
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# Using exceptions for flow control is really bad, but there really seems to
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# be no sane way to get a stream to stop reading in Excon (or Net::HTTP for
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# that matter!)
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raise ReadEnough.new if result.size > 1024
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end
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Excon.get(uri.to_s, response_block: streamer, read_timeout: 20, headers: CrawlTopicLink.request_headers(uri))
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result
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rescue ReadEnough
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result
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end
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def execute(args)
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raise Discourse::InvalidParameters.new(:topic_link_id) unless args[:topic_link_id].present?
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begin
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topic_link = TopicLink.where(id: args[:topic_link_id], internal: false, crawled_at: nil).first
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return if topic_link.blank?
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crawled = false
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result = CrawlTopicLink.fetch_beginning(topic_link.url)
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doc = Nokogiri::HTML(result)
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if doc
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title = doc.at('title').try(:inner_text)
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if title.present?
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title.gsub!(/\n/, ' ')
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title.gsub!(/ +/, ' ')
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title.strip!
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if title.present?
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crawled = topic_link.update_attributes(title: title[0..255], crawled_at: Time.now)
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end
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end
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end
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rescue Exception
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# If there was a connection error, do nothing
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ensure
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topic_link.update_column(:crawled_at, Time.now) if !crawled && topic_link.present?
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end
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end
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end
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end
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