Class: FeedTools::FeedUpdater

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

Overview

A simple daemon for scheduled updating of feeds.

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.on_begin(&block) ⇒ Object

Declares an on_begin event. The given block will be called before the update sequence runs to allow for any setup required. The block is not passed any arguments.



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# File 'lib/feed_updater.rb', line 100

def self.on_begin(&block)
  raise "No block supplied for on_begin." if block.nil?
  @@on_begin = block
end

.on_complete(&block) ⇒ Object

Declares an on_complete event. The given block will be called after all feeds have been updated. The block is passed a list of feeds that FeedUpdater attempted to update.



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# File 'lib/feed_updater.rb', line 124

def self.on_complete(&block)
  raise "No block supplied for on_complete." if block.nil?
  @@on_complete = block
end

.on_error(&block) ⇒ Object

Declares an on_error event. The given block will be called after an error occurs during a feed update. The block is passed the href of the feed that errored out, and the exception object that was raised.



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# File 'lib/feed_updater.rb', line 116

def self.on_error(&block)
  raise "No block supplied for on_error." if block.nil?
  @@on_error = block
end

.on_update(&block) ⇒ Object

Declares an on_update event. The given block will be called after every feed update. The block is passed the feed object that was loaded and the time it took in seconds to successfully load it.



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# File 'lib/feed_updater.rb', line 108

def self.on_update(&block)
  raise "No block supplied for on_update." if block.nil?
  @@on_update = block
end

Instance Method Details

#application ⇒ Object

Returns a reference to the daemon application.



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# File 'lib/feed_updater.rb', line 252

def application()
  @application = nil if !defined?(@application)
  return @application
end

#daemon_options ⇒ Object

Returns a hash of the currently set daemon options.



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# File 'lib/feed_updater.rb', line 237

def daemon_options()
  if !defined?(@daemon_options) || @daemon_options.nil?
    @daemon_options = {
      :app_name => "feed_updater_daemon",
      :dir_mode => :normal,
      :dir => self.pid_file_dir,
      :backtrace => true,
      :ontop => false
    }
  end
  @daemon_options[:dir] = self.pid_file_dir
  return @daemon_options
end

#feed_href_list ⇒ Object

Returns a list of feeds to be updated.



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# File 'lib/feed_updater.rb', line 197

def feed_href_list()
  if !defined?(@feed_href_list) || @feed_href_list.nil?
    @feed_href_list_override = false
    if self.updater_options.nil?
      @feed_href_list = nil
    elsif self.updater_options[:feed_href_list].kind_of?(Array)
      @feed_href_list = self.updater_options[:feed_href_list]
    else
      @feed_href_list = nil
    end
  end
  return @feed_href_list
end

#feed_href_list=(new_feed_href_list) ⇒ Object

Sets a list of feeds to be updated.



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# File 'lib/feed_updater.rb', line 212

def feed_href_list=(new_feed_href_list)
  @feed_href_list_override = true
  @feed_href_list = new_feed_href_list
end

#initial_directory ⇒ Object

Returns the initial directory that the daemon was started from.



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# File 'lib/feed_updater.rb', line 130

def initial_directory()
  @initial_directory = nil if !defined?(@initial_directory)
  return @initial_directory
end

#log_file ⇒ Object

Returns the path to the log file.



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# File 'lib/feed_updater.rb', line 158

def log_file()
  if !defined?(@log_file) || @log_file.nil?
    if self.log_file_dir.nil?
      @log_file = File.expand_path("./feed_updater.log")
    else
      @log_file = File.expand_path(
        self.log_file_dir + "/feed_updater.log")
    end
  end
  return @log_file
end

#log_file_dir ⇒ Object

Returns the directory where the log files are stored.



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# File 'lib/feed_updater.rb', line 147

def log_file_dir()
  @log_file_dir = nil if !defined?(@log_file_dir)
  return @log_file_dir
end

#log_file_dir=(new_log_file_dir) ⇒ Object

Sets the directory where the log files are stored.



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# File 'lib/feed_updater.rb', line 153

def log_file_dir=(new_log_file_dir)
  @log_file_dir = new_log_file_dir
end

#logger ⇒ Object

Returns the logger object.



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# File 'lib/feed_updater.rb', line 171

def logger()
  if !defined?(@logger) || @logger.nil?
    @logger = FeedUpdaterLogger.new(self.log_file)
    @logger.level = self.updater_options[:log_level]
    @logger.datetime_format = nil
    @logger.progname = nil
    @logger.prefix = "FeedUpdater".ljust(20)
  end
  return @logger
end

#pid ⇒ Object

Returns the process id of the daemon. This should return nil if the daemon is not running.



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# File 'lib/feed_updater.rb', line 259

def pid()
  if File.exists?(File.expand_path(pid_file_dir + "/feed_updater.pid"))
    begin
      pid_file = File.open(
        File.expand_path(pid_file_dir + "/feed_updater.pid"), "r")
      return pid_file.read.to_s.strip.to_i
    rescue Exception
      return nil
    end
  else
    return nil if self.application.nil?
    begin
      return self.application.pid.pid
    rescue Exception
      return nil
    end
  end
end

#pid_file_dir ⇒ Object

Returns the directory where the pid files are stored.



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# File 'lib/feed_updater.rb', line 136

def pid_file_dir()
  @pid_file_dir = nil if !defined?(@pid_file_dir)
  return @pid_file_dir
end

#pid_file_dir=(new_pid_file_dir) ⇒ Object

Sets the directory where the pid files are stored.



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# File 'lib/feed_updater.rb', line 142

def pid_file_dir=(new_pid_file_dir)
  @pid_file_dir = new_pid_file_dir
end

#restart ⇒ Object

Restarts the daemon.



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# File 'lib/feed_updater.rb', line 430

def restart()
  self.stop()
  self.start()
end

#restart_logger ⇒ Object

Restarts the logger object. This needs to be done after the program forks.



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# File 'lib/feed_updater.rb', line 184

def restart_logger()
  begin
    self.logger.close()
  rescue IOError
  end
  @logger = FeedUpdaterLogger.new(self.log_file)
  @logger.level = self.updater_options[:log_level]
  @logger.datetime_format = nil
  @logger.progname = nil
  @logger.prefix = "FeedUpdater".ljust(20)
end

#start ⇒ Object

Starts the daemon.



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# File 'lib/feed_updater.rb', line 289

def start()
  self.logger.prefix = "FeedUpdater".ljust(20)
  if !defined?(@@on_update) || @@on_update.nil?
    raise "No on_update handler block given."
  end
  if self.status == :running || self.pid != nil
    puts "FeedUpdater is already running."
    return self.pid
  end
  if defined?(ActiveRecord)
    ActiveRecord::Base.allow_concurrency = true
  end

  @initial_directory = File.expand_path(".")

  if @application.nil?
    self.logger()
    feed_update_proc = lambda do
      # Reestablish correct location
      Dir.chdir(File.expand_path(self.initial_directory))

      self.restart_logger()
      
      if FeedTools.configurations[:feed_cache].nil?
        FeedTools.configurations[:feed_cache] =
          "FeedTools::DatabaseFeedCache"
      end
      if !FeedTools.feed_cache.connected?
        FeedTools.feed_cache.initialize_cache()
      end
      if !FeedTools.feed_cache.connected?
        self.logger.fatal(
          "Not connected to the feed cache. Please create database.yml.")
        exit
      end
      
      # A random start delay is introduced so that we don't have multiple
      # feed updater daemons getting kicked off at the same time by
      # multiple users.
      if self.updater_options[:start_delay]
        delay = (rand(45) + 15)
        self.logger.info("Startup delay set for #{delay} minutes.")
        sleep(delay.minutes)
      end
      
      # The main feed update loop.
      loop do
        result = nil
        sleepy_time = 1.hour
        begin
          result = Benchmark.measure do
            self.update_feeds()
          end
          self.logger.info(
            "#{@feed_href_list.size} feed(s) updated " +
            "in #{result.real.round} seconds.")
          sleepy_time = 1.hour - result.real.round
        rescue Exception => error
          self.logger.error("Feed update sequence errored out.")
          self.logger.error(error.class.name + ": " + error.message)
          self.logger.error("\n" + error.backtrace.join("\n").to_s)
        end

        @feed_href_list = nil
        @feed_href_list_override = false
        ObjectSpace.garbage_collect()
        if sleepy_time > 0
          self.logger.info(
            "Sleeping for #{(sleepy_time / 60.0).round} minutes...")
          sleep(sleepy_time)
        else
          self.logger.info(
            "Update took more than 60 minutes, restarting immediately.")
        end
      end
    end
    options = self.daemon_options.merge({
      :proc => feed_update_proc,
      :mode => :proc
    })
    @application = Daemons::ApplicationGroup.new(
      'feed_updater', options).new_application(options)
    @application.start()
  else
    @application.start()
  end
  self.logger.prefix = nil
  self.logger.level = 0
  self.logger.info("-" * 79)
  self.logger.info("Daemon started, " +
    "FeedUpdater #{FeedTools::FEED_UPDATER_VERSION::STRING} / " +
    "FeedTools #{FeedTools::FEED_TOOLS_VERSION::STRING}")
  self.logger.info(" @ #{Time.now.utc.to_s}")
  self.logger.info("-" * 79)
  self.logger.level = self.updater_options[:log_level]
  self.logger.prefix = "FeedUpdater".ljust(20)
  @status = :running
  return self.pid
end

#status ⇒ Object

Returns either :running or :stopped depending on the daemon’s current status.



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# File 'lib/feed_updater.rb', line 219

def status()
  @status = :stopped if @status.nil?
  return @status
end

#stop ⇒ Object

Stops the daemon.



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# File 'lib/feed_updater.rb', line 390

def stop()
  if self.pid.nil?
    puts "FeedUpdater isn't running."
  end
  begin
    # Die.
    Process.kill('TERM', self.pid)
  rescue Exception
  end
  begin
    # No, really, I mean it.  You need to die.
    system("kill #{self.pid} 2> /dev/null")
    
    # Perhaps I wasn't clear somehow?
    system("kill -9 #{self.pid} 2> /dev/null")
  rescue Exception
  end
  begin
    # Clean the pid file up.
    if File.exists?(
        File.expand_path(self.pid_file_dir + "/feed_updater.pid"))
      File.delete(
        File.expand_path(self.pid_file_dir + "/feed_updater.pid"))
    end
  rescue Exception
  end
  self.logger.prefix = "FeedUpdater".ljust(20)
  self.logger.level = 0
  self.logger.info("Daemon stopped.")
  self.logger.level = self.updater_options[:log_level]
  @status = :stopped
  return nil if self.application.nil?
  begin
    self.application.stop()
  rescue Exception
  end
  return nil
end

#update_feeds ⇒ Object

Updates all of the feeds.



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# File 'lib/feed_updater.rb', line 436

def update_feeds()
  self.logger.level = 0
  self.logger.prefix = "FeedUpdater".ljust(20)
  ObjectSpace.garbage_collect()
  if defined?(@@on_begin) && @@on_begin != nil
    self.logger.info("Running custom startup event...")
    self.cloaker(&(@@on_begin)).bind(self).call()
  end
  if defined?(@feed_href_list_override) && @feed_href_list_override
    self.logger.info("Using custom feed list...")
    self.feed_href_list()
  else
    self.logger.info("Loading default feed list...")
    begin
      expire_time = (Time.now - 1.hour).utc
      expire_time_string = sprintf('%04d-%02d-%02d %02d:%02d:%02d',
        expire_time.year, expire_time.month, expire_time.day,
        expire_time.hour, expire_time.min, expire_time.sec)
      @feed_href_list =
        FeedTools.feed_cache.connection.execute(
          "SELECT href FROM cached_feeds WHERE " +
          "last_retrieved < '#{expire_time_string}'").to_a.flatten
    rescue Exception
      self.logger.warn("Default feed list failed, using fallback.")
      @feed_href_list =
        FeedTools.feed_cache.find(:all).collect do |feed|
          feed.href
        end
      self.logger.warn(
        "Fallback succeeded. Custom feed list override recommended.")
    end
  end
  self.logger.info("Updating #{@feed_href_list.size} feed(s)...")
  self.logger.level = self.updater_options[:log_level]
  ObjectSpace.garbage_collect()
  
  threads = []
  thread_slices = []
  thread_slice_size =
    (@feed_href_list.size / self.updater_options[:threads])

  for i in 0...self.updater_options[:threads]
    if i != self.updater_options[:threads] - 1
      thread_slices << @feed_href_list[
        (i * thread_slice_size)...((i + 1) * thread_slice_size)]
    else
      thread_slices << @feed_href_list[
        (i * thread_slice_size)..-1]
    end
  end
  ObjectSpace.garbage_collect()

  begin_updating = false
  self.logger.info(
    "Starting up #{self.updater_options[:threads]} thread(s)...")
  
  mutex = Mutex.new
  for i in 0...self.updater_options[:threads]
    updater_thread = Thread.new do
      self.logger.level = self.updater_options[:log_level]
      self.logger.datetime_format = "%s"
      self.logger.progname = "FeedUpdater".ljust(20)
      
      while !Thread.current.respond_to?(:thread_id) &&
          begin_updating == false
        Thread.pass
      end
      mutex.synchronize do
        self.logger.prefix = "Thread #{Thread.current.thread_id} ".ljust(20)
        self.logger.info("Thread started.")
        
        begin
          FeedTools.feed_cache.initialize_cache()
          if !FeedTools.feed_cache.set_up_correctly?
            self.logger.info("Problem with cache connection...")
          end
        rescue Exception => error
          self.logger.info(error)
        end
      
        self.logger.info(
          "Thread ##{Thread.current.thread_id} handling " +
          "#{thread_slices[Thread.current.thread_id].size} feeds...")
      end
      
      ObjectSpace.garbage_collect()
      Thread.pass
      href_list = thread_slices[Thread.current.thread_id]

      for i in 0...href_list.size
        progress = nil
        mutex.synchronize do
          Thread.current.href = href_list[i]
          Thread.current.progress =
            (href_list.index(Thread.current.href).to_f /
              href_list.size.to_f) * 100
          progress = sprintf("%.2f", Thread.current.progress)
        end
        begin
          begin
            Thread.current.feed = nil
            feed_load_benchmark = Benchmark.measure do
              Thread.current.feed =
                FeedTools::Feed.open(Thread.current.href)
            end
            Thread.pass
            if Thread.current.feed.live?
              unless @@on_update.nil?
                mutex.synchronize do
                  progress = sprintf("%.2f", Thread.current.progress)
                  self.logger.prefix = 
                    ("Thread #{Thread.current.thread_id} (#{progress}%)"
                      ).ljust(20)
                  self.cloaker(&(@@on_update)).bind(self).call(
                    Thread.current.feed, feed_load_benchmark.real)
                end
              end
            else
              mutex.synchronize do
                progress = sprintf("%.2f", Thread.current.progress)
                self.logger.prefix = 
                  ("Thread #{Thread.current.thread_id} (#{progress}%)"
                    ).ljust(20)
                self.logger.info(
                  "'#{Thread.current.href}' unchanged " +
                  "or unavailable, skipping.")
              end
            end
          rescue Exception => error
            mutex.synchronize do
              progress = sprintf("%.2f", Thread.current.progress)
              self.logger.prefix = 
                ("Thread #{Thread.current.thread_id} (#{progress}%)"
                  ).ljust(20)
              if @@on_error != nil
                self.cloaker(&(@@on_error)).bind(self).call(
                  Thread.current.href, error)
              else
                self.logger.error(
                  "Error updating '#{Thread.current.href}':")
                self.logger.error(error.class.name + ": " + error.message)
                self.logger.error(error.class.backtrace)
              end
            end
          end
        rescue Exception => error
          mutex.synchronize do
            progress = sprintf("%.2f", Thread.current.progress)
            self.logger.prefix = ("Thread #{Thread.current.thread_id} " +
              "(#{progress}%)"
              ).ljust(20)
            self.logger.fatal("Critical unhandled error.")
            self.logger.fatal("Error updating '#{Thread.current.href}':")
            self.logger.fatal(error.class.name + ": " + error.message)
            self.logger.fatal(error.class.backtrace)
          end
        end
        ObjectSpace.garbage_collect()
        Thread.pass
      end          
    end
    threads << updater_thread        
    class <<updater_thread
      attr_accessor :thread_id
      attr_accessor :progress
      attr_accessor :href
      attr_accessor :feed
    end
    updater_thread.thread_id = i
  end
  mutex.synchronize do
    self.logger.prefix = "FeedUpdater".ljust(20)
    self.logger.info(
      "#{threads.size} thread(s) successfully started...")
    begin_updating = true
  end
  Thread.pass
  
  ObjectSpace.garbage_collect()
  Thread.pass
  for i in 0...threads.size
    mutex.synchronize do
      self.logger.prefix = "FeedUpdater".ljust(20)
      self.logger.info(
        "Joining on thread #{threads[i].thread_id}...")
    end
    threads[i].join
  end
  self.logger.prefix = "FeedUpdater".ljust(20)
  ObjectSpace.garbage_collect()
  
  self.logger.progname = nil
  unless @@on_complete.nil?
    self.cloaker(&(@@on_complete)).bind(self).call(@feed_href_list)
  end
  self.logger.level = 0
  self.logger.info("Finished updating.")
  self.logger.level = self.updater_options[:log_level]
end

#updater_options ⇒ Object

Returns a hash of the currently set updater options.



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# File 'lib/feed_updater.rb', line 225

def updater_options()
  if !defined?(@updater_options) || @updater_options.nil?
    @updater_options = {
      :start_delay => true,
      :thread => 1,
      :log_level => 0
    }
  end
  return @updater_options
end