Class: CountedCache

Inherits:
Object
  • Object
show all
Defined in:
lib/counted_cache.rb,
lib/counted_cache/version.rb

Constant Summary collapse

VERSION = 
"0.2.0".freeze
DESCRIPTION = 
"counted_cache: A cache for mostly read data with a high cost of retrieval.".freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(depth = 10, &load_block) ⇒ CountedCache

Setup the cache



20
21
22
23
24
25
26
27
28
29
30
 
# File 'lib/counted_cache.rb', line 20

def initialize(depth = 10, &load_block)
  fail "A data loading block is required" unless block_given?

  @load_block = load_block
  @save_block = Proc.new {}
  @key_space  = Hash.new {|hash, key| hash[key] = CountedCacheItem.new(key)}
  @data_space = Array.new
  self.depth  = depth
  @hits       = 0
  @misses     = 0
end

Instance Attribute Details

#depth ⇒ Object

How many data elements should be retained?



11
12
13
 
# File 'lib/counted_cache.rb', line 11

def depth
  @depth
end

#hits ⇒ Object (readonly)

How many times was data found in the cache?



14
15
16
 
# File 'lib/counted_cache.rb', line 14

def hits
  @hits
end

#misses ⇒ Object (readonly)

How many times was data not in the cache?



17
18
19
 
# File 'lib/counted_cache.rb', line 17

def misses
  @misses
end

Instance Method Details

#[](key) ⇒ Object

Get a data item.



38
39
40
41
42
43
44
45
46
47
48
49
50
51
 
# File 'lib/counted_cache.rb', line 38

def [](key)
  item = @key_space[key]

  if item.empty?
    item.data = @load_block.call(key)
    adjust_cache(1)
    @data_space << item
    @misses += 1
  else
    @hits += 1
  end

  item.data
end

#free ⇒ Object

How many cache slots are free?



62
63
64
 
# File 'lib/counted_cache.rb', line 62

def free
  @depth - @data_space.length
end

#set_save_block(&save_block) ⇒ Object

Set up the optional block called to save data.



33
34
35
 
# File 'lib/counted_cache.rb', line 33

def set_save_block(&save_block)
  @save_block = save_block
end