Class: LitmusPaper::Cache

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

Instance Method Summary collapse

Constructor Details

#initialize(location, namespace, ttl) ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/litmus_paper/cache.rb', line 7

def initialize(location, namespace, ttl)
  @path = File.join(location, namespace)
  @ttl = ttl

  FileUtils.mkdir_p(@path)
end

Instance Method Details

#_entry(ttl, value) ⇒ Object 



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# File 'lib/litmus_paper/cache.rb', line 47

def _entry(ttl, value)
  "#{Time.now.to_f + ttl} #{YAML::dump(value)}"
end

#get(key) ⇒ Object 



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# File 'lib/litmus_paper/cache.rb', line 37

def get(key)
  return unless File.exists?(File.join(@path, key))
  File.open(File.join(@path, key), "r") do |f|
    f.flock(File::LOCK_SH)
    entry = f.read
    expires_at, value = entry.split(" ", 2)
    expires_at.to_f < Time.now.to_f ? nil : YAML::load(value)
  end
end

#set(key, value) ⇒ Object 



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# File 'lib/litmus_paper/cache.rb', line 14

def set(key, value)
  return unless @ttl > 0
  filename = File.join(@path, key)
  if File.exist?(filename)
    File.open(filename, "r+") do |f|
      f.flock(File::LOCK_EX)
      f.rewind
      f.write(_entry(@ttl, value))
      f.flush
      f.truncate(f.pos)
    end
  else
    temp = Tempfile.new("#{key}_init", @path)
    begin
      temp.write(_entry(@ttl, value))
      temp.flush
    ensure
      temp.close
    end
    FileUtils.mv(temp.path, filename)
  end
end