Class: Fetcher::Worker

Inherits:
Object
  • Object
show all
Includes:
LogUtils::Logging
Defined in:
lib/fetcher/worker.rb

Instance Method Summary collapse

Constructor Details

#initialize(old_logger_do_not_use = nil) ⇒ Worker

todo/fix: remove logger from c’tor

use logutils instead



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# File 'lib/fetcher/worker.rb', line 13

def initialize( old_logger_do_not_use=nil )
  if old_logger_do_not_use != nil
     puts "*** depreciated API call [Fetcher.initialize] - do NOT pass in logger; no longer required/needed; logger arg will get removed"
  end
  
  ### cache for conditional get (e.g. etags and last-modified headers/checks)
  @cache = {}
  @use_cache = false
end

Instance Method Details

#cache ⇒ Object 



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# File 'lib/fetcher/worker.rb', line 26

def cache()                    @cache;                   end

#clear_cache ⇒ Object

note: use cache[ uri ] = hash for headers+plus body+plus code(410,etc.)

cache[ uri ]



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# File 'lib/fetcher/worker.rb', line 25

def clear_cache()              @cache = {};              end

#copy(src, dest) ⇒ Object 



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# File 'lib/fetcher/worker.rb', line 52

def copy( src, dest )
  ### fix: return true - success or
  #               false - error!!!

  ## todo: add file protocol - why? why not??

  logger.debug "fetch - copy src: #{src} to dest: #{dest}"

  response = get_response( src )

  # on error return; do NOT copy file; sorry
  return  if response.code != '200'

  # check for content type; use 'wb' for images
  if response.content_type =~ /image/
    logger.debug '  switching to binary'
    flags = 'wb'
  else
    flags = 'w'
  end
  
  File.open( dest, flags ) do |f|
    f.write( response.body )
  end
end

#get(src) ⇒ Object 



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# File 'lib/fetcher/worker.rb', line 31

def get( src )
  # return HTTPResponse (code,message,body,etc.)
  logger.debug "fetch - get(_response) src: #{src}"

  get_response( src )
end

#get_response(src) ⇒ Object

todo: add file protocol



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# File 'lib/fetcher/worker.rb', line 81

def get_response( src )
  uri = URI.parse( src )
  
  # new code: honor proxy env variable HTTP_PROXY
  proxy = ENV['HTTP_PROXY']
  proxy = ENV['http_proxy'] if proxy.nil?   # try possible lower/case env variable (for *nix systems) is this necessary??

  if proxy
    proxy = URI.parse( proxy )
    logger.debug "using net http proxy: proxy.host=#{proxy.host}, proxy.port=#{proxy.port}"
    if proxy.user && proxy.password
      logger.debug "  using credentials: proxy.user=#{proxy.user}, proxy.password=****"
    else
      logger.debug "  using no credentials"
    end
  else
    logger.debug "using direct net http access; no proxy configured"
    proxy = OpenStruct.new   # all fields return nil (e.g. proxy.host, etc.)
  end
  
  http_proxy = Net::HTTP::Proxy( proxy.host, proxy.port, proxy.user, proxy.password )

  redirect_limit = 4
  response = nil

  until false
    raise ArgumentError, 'HTTP redirect too deep' if redirect_limit == 0
    redirect_limit -= 1
  
    http = http_proxy.new( uri.host, uri.port )

    logger.debug "GET #{uri.request_uri} uri=#{uri}, redirect_limit=#{redirect_limit}"

    headers = { 'User-Agent' => "fetcher gem v#{VERSION}" }

    if use_cache?
      ## check for existing cache entry in cache store (lookup by uri)
      ## todo/fix: normalize uri!!!! - how?
      ##  - remove query_string ?? fragement ?? why? why not??
      
      ## note:  using uri.to_s  should return full uri e.g. http://example.com/page.html


      cache_entry = cache[ uri.to_s ]
      if cache_entry
        logger.info "found cache entry for >#{uri.to_s}<"
        if cache_entry['etag']
          logger.info "adding header If-None-Match (etag) >#{cache_entry['etag']}< for conditional GET"
          headers['If-None-Match'] = cache_entry['etag']
        end
        if cache_entry['last-modified']
          logger.info "adding header If-Modified-Since (last-modified) >#{cache_entry['last-modified']}< for conditional GET"
          headers['If-Modified-Since'] = cache_entry['last-modified']
        end
      end
    end

    request = Net::HTTP::Get.new( uri.request_uri, headers )
    if uri.instance_of? URI::HTTPS
      http.use_ssl = true
      http.verify_mode = OpenSSL::SSL::VERIFY_NONE
    end

    response   = http.request( request )  

    if response.code == '200'
      logger.debug "#{response.code} #{response.message}"
      logger.debug "  content_type: #{response.content_type}, content_length: #{response.content_length}"
      break  # will return response
    elsif( response.code == '304' ) # -- Not Modified - for conditional GETs (using etag,last-modified)
      logger.debug "#{response.code} #{response.message}"
      break  # will return response
    elsif( response.code == '301' || response.code == '302' || response.code == '303' || response.code == '307' )
      # 301 = moved permanently
      # 302 = found
      # 303 = see other
      # 307 = temporary redirect
      logger.debug "#{response.code} #{response.message} location=#{response.header['location']}"
      newuri = URI.parse( response.header['location'] )
      if newuri.relative?
        logger.debug "url relative; try to make it absolute"
        newuri = uri + response.header['location']
      end
      uri = newuri
    else
      puts "*** error - fetch HTTP - #{response.code} #{response.message}"
      break  # will return response
    end
  end

  response
end

#read(src) ⇒ Object 



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# File 'lib/fetcher/worker.rb', line 39

def read( src )
  # return contents (response body) a string
  logger.debug "fetch - copy src: #{src} into string"
  
  response = get_response( src )
  
  # on error return empty string; - check: better return nil- why? why not??
  return ''  if response.code != '200'

  response.body.dup  # return string copy
end

#use_cache=(true_or_false) ⇒ Object

true|false



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# File 'lib/fetcher/worker.rb', line 27

def use_cache=(true_or_false)  @use_cache=true_or_false; end

#use_cache? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/fetcher/worker.rb', line 28

def use_cache?()               @use_cache;               end