Class LRUCache
In: lib/more/facets/lrucache.rb
Parent: Hash

LRUCache

A cache utilizing a simple LRU (Least Recently Used) policy. The items managed by this cache must respond to the key method. Attempts to optimize reads rather than inserts!

LRU semantics are enforced by inserting the items in a queue. The lru item is always at the tail. Two special sentinels (head, tail) are used to simplify (?) the code.

Methods

[]   []=   clear   delete   first   last   lru   new  

Classes and Modules

Module LRUCache::Item
Class LRUCache::Sentinel

Attributes

head  [R]  the head sentinel and the tail sentinel, tail.prev points to the lru item.
max_items  [RW]  the maximum number of items in the cache.
tail  [R]  the head sentinel and the tail sentinel, tail.prev points to the lru item.

Public Class methods

[Source]

# File lib/more/facets/lrucache.rb, line 59
  def initialize(max_items)
    @max_items = max_items
    lru_clear()
  end

Public Instance methods

Lookup an item in the cache.

[Source]

# File lib/more/facets/lrucache.rb, line 66
  def [](key)
    if item = super
      return lru_touch(item)
    end
  end

The inserted item is considered mru!

[Source]

# File lib/more/facets/lrucache.rb, line 74
  def []=(key, item)
    item = super
    item.lru_key = key
    lru_insert(item)
  end

Clear the cache.

[Source]

# File lib/more/facets/lrucache.rb, line 90
  def clear
    super
    lru_clear()
  end

Delete an item from the cache.

[Source]

# File lib/more/facets/lrucache.rb, line 82
  def delete(key)
    if item = super
      lru_delete(item)
    end
  end

The first (mru) element in the cache.

[Source]

# File lib/more/facets/lrucache.rb, line 97
  def first
    @head.lru_next
  end

The last (lru) element in the cache.

[Source]

# File lib/more/facets/lrucache.rb, line 103
  def last
    @tail.lru_prev
  end
lru()

Alias for last

[Validate]