Class: LargeObjectStore::RailsWrapper

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

Constant Summary collapse

LIMIT = 
1024**2 - 100

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(store) ⇒ RailsWrapper

Returns a new instance of RailsWrapper.



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# File 'lib/large_object_store.rb', line 14

def initialize(store)
  @store = store
end

Instance Attribute Details

#store ⇒ Object (readonly)

Returns the value of attribute store.



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# File 'lib/large_object_store.rb', line 10

def store
  @store
end

Instance Method Details

#fetch(key, options = {}) ⇒ Object 



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# File 'lib/large_object_store.rb', line 59

def fetch(key, options={})
  value = read(key)
  return value unless value.nil?
  value = yield
  write(key, value, options)
  value
end

#read(key) ⇒ Object 



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# File 'lib/large_object_store.rb', line 42

def read(key)
  # read pages
  pages = @store.read("#{key}_0")
  return if pages.nil?

  data = if pages.is_a?(String)
    pages
  else
    # read sliced data
    keys = Array.new(pages).each_with_index.map{|_,i| "#{key}_#{i+1}" }
    slices = @store.read_multi(*keys).values
    return nil if slices.compact.size < pages
    slices.join("")
  end
  Marshal.load(data)
end

#write(key, value, options = {}) ⇒ Object 



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# File 'lib/large_object_store.rb', line 18

def write(key, value, options = {})
  value = Marshal.dump(value)
  
  # store number of pages
  pages = (value.size / LIMIT.to_f).ceil

  if pages == 1
    @store.write("#{key}_0", value, options)
  else
    @store.write("#{key}_0", pages, options)

    # store object
    page = 1
    loop do
      slice = value.slice!(0, LIMIT)
      break if slice.size == 0

      @store.write("#{key}_#{page}", slice, options)
      page += 1
    end
  end
  true
end