mirror of
https://github.com/discourse/discourse.git
synced 2024-11-27 23:03:38 +08:00
98 lines
3.3 KiB
Ruby
98 lines
3.3 KiB
Ruby
require 'open-uri'
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require 'nokogiri'
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require 'excon'
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require 'final_destination'
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module Jobs
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class CrawlTopicLink < Jobs::Base
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class ReadEnough < StandardError; end
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def self.max_chunk_size(uri)
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# Amazon leaves the title until very late. Normally it's a bad idea to make an exception for
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# one host but amazon is a big one.
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return 80 if uri.host =~ /amazon\.(com|ca|co\.uk|es|fr|de|it|com\.au|com\.br|cn|in|co\.jp|com\.mx)$/
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# Default is 10k
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10
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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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fd = FinalDestination.new(url)
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uri = fd.resolve
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return "" unless uri
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result = ""
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streamer = lambda do |chunk, _, _|
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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 > (CrawlTopicLink.max_chunk_size(uri) * 1024)
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end
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Excon.get(uri.to_s, response_block: streamer, read_timeout: 20, headers: fd.request_headers)
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result
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rescue Excon::Errors::SocketError => ex
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return result if ex.socket_error.is_a?(ReadEnough)
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raise
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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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topic_link = TopicLink.find_by(id: args[:topic_link_id], internal: false, crawled_at: nil)
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return if topic_link.blank?
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# Look for a topic embed for the URL. If it exists, use its title and don't crawl
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topic_embed = TopicEmbed.where(embed_url: topic_link.url).includes(:topic).references(:topic).first
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# topic could be deleted, so skip
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if topic_embed && topic_embed.topic
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TopicLink.where(id: topic_link.id).update_all(['title = ?, crawled_at = CURRENT_TIMESTAMP', topic_embed.topic.title[0..255]])
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return
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end
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begin
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crawled = false
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# Special case: Images
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# If the link is to an image, put the filename as the title
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if topic_link.url =~ /\.(jpg|gif|png)$/
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uri = URI(topic_link.url)
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filename = File.basename(uri.path)
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crawled = (TopicLink.where(id: topic_link.id).update_all(["title = ?, crawled_at = CURRENT_TIMESTAMP", filename]) == 1)
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end
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unless crawled
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# Fetch the beginning of the document to find the title
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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 = (TopicLink.where(id: topic_link.id).update_all(['title = ?, crawled_at = CURRENT_TIMESTAMP', title[0..254]]) == 1)
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end
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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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TopicLink.where(id: topic_link.id).update_all('crawled_at = CURRENT_TIMESTAMP') 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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