canvas-lms/lib/external_feed_aggregator.rb

130 lines
4.1 KiB
Ruby

#
# Copyright (C) 2011 Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#
class ExternalFeedAggregator
SUCCESS_WAIT_SECONDS = 1.hour # time to refresh on a successful feed load with new entries
NO_ENTRIES_WAIT_SECONDS = 2.hours # time to refresh on a successful feed load with NO new entries
FAILURE_WAIT_SECONDS = 30.minutes # time to refresh on a failed feed load
def self.process
ExternalFeedAggregator.new.process
end
def initialize
@logger = RAILS_DEFAULT_LOGGER
end
def process
ExternalFeed.to_be_polled.each do |feed|
process_feed(feed)
end
end
def parse_entries(feed, body)
if feed.feed_type == 'rss/atom'
begin
require 'rss/1.0'
require 'rss/2.0'
rss = RSS::Parser.parse(body, false)
raise "Invalid rss feed" unless rss
feed.title = rss.channel.title
feed.save
@logger.info("#{rss.items.length} rss items found")
entries = feed.add_rss_entries(rss)
@logger.info("#{entries.length} new entries added")
return true
rescue
begin
require 'atom'
atom = Atom::Feed.load_feed(body)
feed.title = atom.title
feed.save
@logger.info("#{atom.entries.length} atom entries found")
entries = feed.add_atom_entries(atom)
@logger.info("#{entries.length} new entries added")
return true
rescue
end
end
elsif feed.feed_type == 'ical'
require 'icalendar'
begin
cals = Icalendar.parse(body)
tally = []
entries = []
cals.each do |cal|
tally += feed.events
entries += feed.add_ical_entries(cal)
end
@logger.info("#{tally.length} ical events found")
@logger.info("#{entries.length} new entries added")
return true
rescue
end
end
false
end
def request_feed(url, attempt=0)
return nil if attempt > 2
url = URI.parse url
http = Net::HTTP.new(url.host, url.port)
request = Net::HTTP::Get.new(url.path)
response = http.request(request)
case response
when Net::HTTPSuccess
return response
when Net::HTTPRedirection
return new_response = request_feed(response['Location'], attempt + 1) || response
else
return response
end
end
def process_feed(feed)
begin
@logger.info("feed found: #{feed.url}")
@logger.info('requesting entries')
require 'net/http'
response = request_feed(feed.url)
case response
when Net::HTTPSuccess
success = parse_entries(feed, response.body)
@logger.info(success ? 'successful response' : '200 with no data returned')
feed.consecutive_failures = 0 if success
feed.update_attribute(:refresh_at, Time.now.utc + ((!@entries || @entries.empty?) ? NO_ENTRIES_WAIT_SECONDS : SUCCESS_WAIT_SECONDS))
else
@logger.info("request failed #{response.class.to_s}")
feed.increment(:consecutive_failures)
feed.increment(:failures)
feed.update_attribute(:refresh_at, Time.now.utc + (FAILURE_WAIT_SECONDS))
end
rescue => e
feed.increment(:consecutive_failures)
feed.increment(:failures)
feed.update_attribute(:refresh_at, Time.now.utc + (FAILURE_WAIT_SECONDS))
ErrorReport.log_exception(:default, e, {
:message => "External Feed aggregation failed",
:feed_url => feed.url,
:feed_id => feed.id,
:user_id => feed.user_id,
})
end
end
end