Class: LWAC::DownloadClient

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

Instance Method Summary collapse

Constructor Details

#initialize(config) ⇒ DownloadClient

Construct a new DownloadClient



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# File 'lib/lwac/client.rb', line 23

def initialize(config)
  # Save the config
  @config = config

  # Generate a unique identifier for this host
  @uuid = generate_uuid

  # Fire up el RPC client...
  @rpc_client = SimpleRPC::Client.new(@config[:server])

  # Don't RPC again until...
  @rpc_delay    = Time.now

  # Construct a new multi-curl thingy
  $log.info "Starting download engine..."
  @dl = Blat::Queue.new(@config[:client][:simultaneous_workers])

  # List of links pending, cached.
  @links        = []
  @cache        = new_cache
  @cache_bytes  = 0

  # Mutices for link access
  @link_mx      = Mutex.new
  @cache_mx     = Mutex.new

  # Don't try to acquire more data until...
  @checkout_delay = Time.now

  # Start the log with UUID info.
  $log.info "Client started with UUID: #{@uuid}"

  # ping for helpfulness
  ping
end

Instance Method Details

#work ⇒ Object

Poll the server and download from the web, maintaining throughput to the web by downloading batches of links.



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# File 'lib/lwac/client.rb', line 61

def work

  loop do
    @dl.perform do

      sleep(@config[:client][:monitor_rate])

      # Keep the download queue topped up
      while @dl.request_count < @config[:client][:simultaneous_workers] && (new_link = get_curl)
        @dl.add(new_link)
      end

      # Read things safely using a mutex
      link_len          = @link_mx.synchronize { @links.length }
      active_requests   = @dl.request_count
      cache_len, bytes  = @cache_mx.synchronize { [@cache.length, @cache_bytes] }

      # Print nice progress output for folks
      if @config[:client][:announce_progress] && (link_len > 0 || cache_len > 0 || active_requests > 0)
        progress_mb      = bytes.to_f / 1024 / 1024
        limit_mb         = @config[:client][:cache_limit].to_f / 1024 / 1024
        pc_progress      = (progress_mb / limit_mb) * 100

        str =  "#{progress_bar(@config[:client][:cache_limit], bytes)} #{pc_progress.round}%"
        str += " #{progress_mb.round(2)}/#{limit_mb.round(2)}MB"
        str += " (#{link_len} pend, #{active_requests} active, #{cache_len} done)"
        str += " #{(link_len == 0 && Time.now < @checkout_delay) ? "[waiting #{(@checkout_delay - Time.now).round}s]" : ''}"
        
        $log.info(str)
      end

      # Run out of links
      if link_len <= 0 && Time.now > @checkout_delay 
        acquire_links
      end

      # Downloaded enough data already
      if (@dl.idle? || bytes > @config[:client][:cache_limit]) && cache_len > 0
        # (@pool.cache_size.to_f / 1024.0 / 1024.0) > @config[:client][:cache_limit] then
        # Send completed points back to the server
        send_cache
      end
    end

    $log.debug "Downloader is idle."

  end

rescue SignalException => se
  $log.fatal "Caught signal - #{se}"
ensure
  # Cancel web requests
  cancelled = @dl.request_count
  if @dl.request_count > 0
    $log.info "Cancelling #{@dl.request_count} web requests..."
    @dl.cancel
  else
    $log.info "No web requests active."
  end

  # Tell the server we're dying
  if @links.length > 0 || @cache.length > 0 || @dl.request_count > 0
    $log.info "Releasing lock on approx. #{@links.length + @cache.length + cancelled} links..."
    rpc(5) do |s|
      s.cancel(LWAC::VERSION, @uuid)
    end
  else
    $log.info "No links to clean up."
  end
  
  # Quit
  $log.info "Done.  Client has closed cleanly."
end