jam-cloud/ruby/lib/jam_ruby/resque/quick_mixer.rb

require 'json'
require 'resque'
require 'resque-retry'
require 'net/http'
require 'digest/md5'

module JamRuby

  # executes a mix of tracks, creating a final output mix
  class QuickMixer
    extend JamRuby::ResqueStats

    @queue = :quick_mixer

    @@log = Logging.logger[QuickMixer]

    attr_accessor :quick_mix_id, :quick_mix, :output_filename, :error_out_filename,
                  :postback_mp3_url, :error_reason, :error_detail

    def self.perform(quick_mix_id, postback_mp3_url)

      audiomixer = QuickMixer.new
      audiomixer.postback_mp3_url = postback_mp3_url
      audiomixer.quick_mix_id = quick_mix_id
      audiomixer.run

    end

    def self.find_jobs_needing_retry &blk
      QuickMix.find_each(:conditions => "completed = FALSE AND (should_retry = TRUE OR (started_at IS NOT NULL AND NOW() - started_at > '1 hour'::INTERVAL))", :batch_size => 100) do |mix|
        blk.call(mix)
      end
    end

    def self.queue_jobs_needing_retry
      find_jobs_needing_retry do |mix|
        mix.enqueue
      end
    end

    def initialize
      @s3_manager = S3Manager.new(APP_CONFIG.aws_bucket, APP_CONFIG.aws_access_key_id, APP_CONFIG.aws_secret_access_key)
    end

    def run
      @@log.info("quickmixer job starting. quick_mix_id #{quick_mix_id}")

      @quick_mix = QuickMix.find(quick_mix_id)

      begin
        # bailout check
        if @quick_mix.completed
          @@log.debug("quick mix is already completed. bailing")
          return
        end

        fetch_audio_files

        create_mp3(@input_ogg_filename, @output_mp3_filename)

        postback

        post_success(@quick_mix)

        cleanup_files

        @@log.info("quickmixer job successful. mix_id #{quick_mix_id}")

      rescue Exception => e
        post_error(@quick_mix, e)
        raise
      end
    end


    def postback

      @@log.debug("posting mp3 mix to #{@postback_mp3_url}")

      uri = URI.parse(@postback_mp3_url)
      http = Net::HTTP.new(uri.host, uri.port)
      http.use_ssl = @postback_mp3_url.start_with?('https') ? true : false
      request = Net::HTTP::Put.new(uri.request_uri)

      response = nil
      File.open(@output_mp3_filename,"r") do |f|
        request.body_stream=f
        request["Content-Type"] = "audio/mpeg"
        request.add_field('Content-Length', File.size(@output_mp3_filename))
        response = http.request(request)
      end

      response_code = response.code.to_i
      unless response_code >= 200 && response_code <= 299
        @error_reason = "postback-mp3-mix-to-s3"
        raise "unable to put to url: #{@postback_mp3_url}, status: #{response.code}, body: #{response.body}"
      end

    end

    def post_success(mix)

      mp3_length = File.size(@output_mp3_filename)
      mp3_md5 = Digest::MD5.new
      File.open(@output_mp3_filename, 'rb').each {|line| mp3_md5.update(line)}

      mix.finish(mp3_length, mp3_md5.to_s)
    end

    def post_error(mix, e)
      begin

        # if error_reason is null, assume this is an unhandled error
        unless @error_reason
          @error_reason = "unhandled-job-exception"
          @error_detail = e.to_s
        end
        mix.errored(error_reason, error_detail)

      rescue Exception => e
        @@log.error "unable to post back to the database the error #{e}"
      end
    end

    def cleanup_files()
      File.delete(@input_ogg_filename) if File.exists?(@input_ogg_filename)
      File.delete(@output_mp3_filename) if File.exists?(@output_mp3_filename)
    end


    def fetch_audio_files
      @input_ogg_filename  = Dir::Tmpname.make_tmpname( ["#{Dir.tmpdir}/quick_mixer_#{@quick_mix.id}}", '.ogg'], nil)
      @output_mp3_filename = Dir::Tmpname.make_tmpname( ["#{Dir.tmpdir}/quick_mixer_#{@quick_mix.id}}", '.mp3'], nil)
      @s3_manager.download(@quick_mix[:ogg_url], @input_ogg_filename)
    end

    private

    def create_mp3(input_ogg_filename, output_mp3_filename)
      ffmpeg_cmd = "#{APP_CONFIG.ffmpeg_path} -i \"#{input_ogg_filename}\" -ab 128k -metadata JamRecordingId=#{@quick_mix.recording_id} -metadata JamQuickMixId=#{@quick_mix_id} -metadata JamType=QuickMix \"#{output_mp3_filename}\""

      system(ffmpeg_cmd)

      unless $? == 0
        @error_reason = 'ffmpeg-failed'
        @error_detail = $?.to_s
        error_msg = "ffmpeg failed status=#{$?} error_reason=#{@error_reason} error_detail=#{@error_detail}"
        @@log.info(error_msg)
        raise error_msg
      end

    end
  end
end