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A cache store implementation which stores everything into memory in the same process. If you're running multiple Ruby on Rails server processes (which is the case if you're using mongrel_cluster or Phusion Passenger), then this means that Rails server process instances won't be able to share cache data with each other and this may not be the most appropriate cache in that scenario.

This cache has a bounded size specified by the :size options to the initializer (default is 32Mb). When the cache exceeds the allotted size, a cleanup will occur which tries to prune the cache down to three quarters of the maximum size by removing the least recently used entries.

MemoryStore is thread-safe.

Methods
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Constants
PER_ENTRY_OVERHEAD = 240
 
Class Public methods
new(options = nil)
# File activesupport/lib/active_support/cache/memory_store.rb, line 19
def initialize(options = nil)
  options ||= {}
  super(options)
  @data = {}
  @key_access = {}
  @max_size = options[:size] || 32.megabytes
  @max_prune_time = options[:max_prune_time] || 2
  @cache_size = 0
  @monitor = Monitor.new
  @pruning = false
end
Instance Public methods
cleanup(options = nil)

Preemptively iterates through all stored keys and removes the ones which have expired.

# File activesupport/lib/active_support/cache/memory_store.rb, line 40
def cleanup(options = nil)
  options = merged_options(options)
  instrument(:cleanup, :size => @data.size) do
    keys = synchronize{ @data.keys }
    keys.each do |key|
      entry = @data[key]
      delete_entry(key, options) if entry && entry.expired?
    end
  end
end
clear(options = nil)
# File activesupport/lib/active_support/cache/memory_store.rb, line 31
def clear(options = nil)
  synchronize do
    @data.clear
    @key_access.clear
    @cache_size = 0
  end
end
decrement(name, amount = 1, options = nil)

Decrement an integer value in the cache.

# File activesupport/lib/active_support/cache/memory_store.rb, line 91
def decrement(name, amount = 1, options = nil)
  synchronize do
    options = merged_options(options)
    if num = read(name, options)
      num = num.to_i - amount
      write(name, num, options)
      num
    else
      nil
    end
  end
end
delete_matched(matcher, options = nil)
# File activesupport/lib/active_support/cache/memory_store.rb, line 104
def delete_matched(matcher, options = nil)
  options = merged_options(options)
  instrument(:delete_matched, matcher.inspect) do
    matcher = key_matcher(matcher, options)
    keys = synchronize { @data.keys }
    keys.each do |key|
      delete_entry(key, options) if key.match(matcher)
    end
  end
end
increment(name, amount = 1, options = nil)

Increment an integer value in the cache.

# File activesupport/lib/active_support/cache/memory_store.rb, line 77
def increment(name, amount = 1, options = nil)
  synchronize do
    options = merged_options(options)
    if num = read(name, options)
      num = num.to_i + amount
      write(name, num, options)
      num
    else
      nil
    end
  end
end
prune(target_size, max_time = nil)

To ensure entries fit within the specified memory prune the cache by removing the least recently accessed entries.

# File activesupport/lib/active_support/cache/memory_store.rb, line 53
def prune(target_size, max_time = nil)
  return if pruning?
  @pruning = true
  begin
    start_time = Time.now
    cleanup
    instrument(:prune, target_size, :from => @cache_size) do
      keys = synchronize{ @key_access.keys.sort{|a,b| @key_access[a].to_f <=> @key_access[b].to_f} }
      keys.each do |key|
        delete_entry(key, options)
        return if @cache_size <= target_size || (max_time && Time.now - start_time > max_time)
      end
    end
  ensure
    @pruning = false
  end
end
pruning?()

Returns true if the cache is currently being pruned.

# File activesupport/lib/active_support/cache/memory_store.rb, line 72
def pruning?
  @pruning
end
Instance Protected methods
cached_size(key, entry)
# File activesupport/lib/active_support/cache/memory_store.rb, line 129
def cached_size(key, entry)
  key.to_s.bytesize + entry.size + PER_ENTRY_OVERHEAD
end