feed_handler.rb
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require 'feedparser'
require 'open-uri'
# This class is responsible for processing feeds and pass the items to the
# respective container.
#
# The <tt>max_errors</tt> attribute controls how many times it will retry in
# case of failure. If a feed fails for <tt>max_errors+1</tt> times, it will be
# disabled and the last error message will be recorder in the container.
# The default value is *6*, if you need to change it you can do that in your
# config/local.rb file like this:
#
# FeedHandler.max_errors = 10
#
# For the update interval, see FeedUpdater.
class FeedHandler
# The maximum number
cattr_accessor :max_errors
cattr_accessor :disabled_period
self.max_errors = 6
self.disabled_period = 1.week
def parse(content)
raise FeedHandler::ParseError, "Content is nil" if content.nil?
begin
return FeedParser::Feed::new(content)
rescue Exception => ex
raise FeedHandler::ParseError, "Invalid feed format."
end
end
def fetch(address)
begin
content = ""
block = lambda { |s| content = s.read }
content =
if RAILS_ENV == 'test' && File.exists?(address)
File.read(address)
else
if !valid_url?(address)
raise InvalidUrl.new("\"%s\" is not a valid URL" % address)
end
open(address, "User-Agent" => "Noosfero/#{Noosfero::VERSION}", &block)
end
return content
rescue Exception => ex
raise FeedHandler::FetchError, ex.message
end
end
def process(container)
RAILS_DEFAULT_LOGGER.info("Processing %s with id = %d" % [container.class.name, container.id])
begin
container.class.transaction do
if container.update_errors > FeedHandler.max_errors && container.fetched_at < (Time.now - FeedHandler.disabled_period)
container.enabled = true
container.update_errors = 0
container.save
end
next unless container.enabled
actually_process_container(container)
container.update_errors = 0
container.finish_fetch
end
rescue Exception => exception
RAILS_DEFAULT_LOGGER.warn("Unknown error from %s ID %d\n%s" % [container.class.name, container.id, exception.to_s])
RAILS_DEFAULT_LOGGER.warn("Backtrace:\n%s" % exception.backtrace.join("\n"))
container.reload
container.update_errors += 1
container.error_message = exception.to_s
if container.update_errors > FeedHandler.max_errors
container.fetched_at = Time.now
container.enabled = false
end
begin
container.finish_fetch
rescue Exception => finish_fetch_exception
RAILS_DEFAULT_LOGGER.warn("Unable to finish fetch from %s ID %d\n%s" % [container.class.name, container.id, finish_fetch_exception.to_s])
RAILS_DEFAULT_LOGGER.warn("Backtrace:\n%s" % finish_fetch_exception.backtrace.join("\n"))
end
end
end
class InvalidUrl < Exception; end
class ParseError < Exception; end
class FetchError < Exception; end
protected
def actually_process_container(container)
container.clear
content = fetch(container.address)
container.fetched_at = Time.now
parsed_feed = parse(content)
container.feed_title = parsed_feed.title
parsed_feed.items[0..container.limit-1].reverse.each do |item|
container.add_item(item.title, item.link, item.date, item.content)
end
end
def valid_url?(url)
url =~ URI.regexp('http') || url =~ URI.regexp('https')
end
end