Class: Rhcf::Utils::DownloadCache

Inherits:
Object
  • Object
show all
Includes:
FileUtils
Defined in:
lib/rhcf/utils/download_cache.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(cache_id = 'default', ttl = nil, root_path = nil) ⇒ DownloadCache

Returns a new instance of DownloadCache.



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# File 'lib/rhcf/utils/download_cache.rb', line 10

def initialize(cache_id= 'default', ttl = nil, root_path = nil)
  @cache_id = cache_id
  @ttl = ttl
  @root_path ||= "/tmp/#{self.class.name}"
end

Class Method Details

.hit_fname?(fname, ttl) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rhcf/utils/download_cache.rb', line 49

def self.hit_fname?(fname, ttl)
  
  if File.exist?(fname) and !File.zero?(fname)
    if ttl
      File::Stat.new(fname).ctime > Time.now - ttl
    else 
      true
    end
  else
    false
  end
end

Instance Method Details

#download!(url, outfile) ⇒ Object 



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# File 'lib/rhcf/utils/download_cache.rb', line 24

def download!(url, outfile)
  uri = URI(url)
  expected_file_size = nil
  Net::HTTP.start(uri.host) do |http|
    resp = http.get(uri.path)

    expected_file_size = resp.body.size
    mkdir_p(File.dirname(outfile))
    File.open(outfile, 'wb') do |fd|
      fd.write(resp.body)
    end
  end

  if expected_file_size != File.size(outfile)
    raise "Different file size expected: '%d' bytes got: '%d' bytes " % [expected_file_size, File.size(outfile)]
  end
  raise "Empty file" if File.zero?(outfile)
  outfile
end

#filename_for(url) ⇒ Object 



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# File 'lib/rhcf/utils/download_cache.rb', line 62

def filename_for(url)
  hash =  Digest::MD5.hexdigest(url)
  uri = URI(url)
  basename = File.basename(uri.path)
  File.join(@root_path, @cache_id, hash_tree(hash), basename) 
end

#get(url) ⇒ Object 



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# File 'lib/rhcf/utils/download_cache.rb', line 17

def get(url)
  outfile = filename_for(url)
  return outfile if self.class.hit_fname?(outfile, @ttl) # here goes the cache
  download!(url, outfile)
end

#hash_tree(hash) ⇒ Object 



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# File 'lib/rhcf/utils/download_cache.rb', line 69

def hash_tree(hash)
  [*(hash[0,3].split('')) ,hash].join('/')
end

#hit?(url) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rhcf/utils/download_cache.rb', line 44

def hit?(url)
  outfile = filename_for(url)
  self.class.hit_fname?(outfile, @ttl) # here goes the cache
end