Class: Xampl::XamplCacheLFU

Inherits:
Object
  • Object
show all
Defined in:
lib/xamplr/persisters/caches.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(capacity = DEFAULT_CAPACITY) ⇒ XamplCacheLFU

Returns a new instance of XamplCacheLFU.



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# File 'lib/xamplr/persisters/caches.rb', line 104

def initialize(capacity=DEFAULT_CAPACITY)
  @capacity = capacity
  @accesses = 0
  @size = 0
  @cache = {}
end

Instance Attribute Details

#cache ⇒ Object (readonly)

Returns the value of attribute cache.



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# File 'lib/xamplr/persisters/caches.rb', line 102

def cache
  @cache
end

#capacity ⇒ Object (readonly)

Returns the value of attribute capacity.



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# File 'lib/xamplr/persisters/caches.rb', line 102

def capacity
  @capacity
end

Instance Method Details

#delete(key) ⇒ Object 



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# File 'lib/xamplr/persisters/caches.rb', line 116

def delete(key)
  @cache.delete(key)
end

#fetch(key, default_value = nil) ⇒ Object Also known as: [] 



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# File 'lib/xamplr/persisters/caches.rb', line 144

def fetch(key, default_value=nil)
  @accesses += 1

  pair = @cache[key]
  if pair then
    pair[1] += 1
    return pair[0]
  else
    return default_value
  end
end

#limit ⇒ Object 



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# File 'lib/xamplr/persisters/caches.rb', line 120

def limit
  victim = nil
  actual_victim = nil
  min = 1 + @accesses
  live = 0
  @cache.each do |key, pair|
    pair[1] -= 1
    possibility = pair[0]
    if (not possibility.load_needed) and pair[1] < min then
      live += 1
      victim = key
      actual_victim = possibility
      min = pair[1]
    end
  end
#puts
  #puts
  #puts "REMOVE FROM CACHE(XamplCacheLFU): victim: #{victim}, actual: #{actual_victim} -- live: #{live}, size: #{@size}"
  #puts
  #puts
  #@cache.delete(victim)
  actual_victim.force_load if actual_victim
end

#print(out = "") ⇒ Object 



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# File 'lib/xamplr/persisters/caches.rb', line 174

def print(out = "")
  out << "Cache (LFU) with capacity: #{@capacity}, current size: #{@size}\n"
  @cache.each do |key, pair|
    out << sprintf("  key: '%s', value: '%s', count: %s\n",
                   key, pair[0], pair[1])
  end
  out
end

#size ⇒ Object 



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# File 'lib/xamplr/persisters/caches.rb', line 111

def size
  #@cache.size
  @size
end

#store(key, value) ⇒ Object Also known as: []= 



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# File 'lib/xamplr/persisters/caches.rb', line 156

def store(key, value)
  @accesses += 1

  if (@capacity <= @size) then
    self.limit
  end

  pair = @cache[key]
  if pair then
    pair[0] = value
    pair[1] += 1
  else
    @cache[key] = [value, 1]
  end

  return value
end