Class: ActiveSupport::Cache::MemoryStore

Inherits:
Store show all
Defined in:
activesupport/lib/active_support/cache/memory_store.rb

Overview

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.

Constant Summary

Instance Attribute Summary

Attributes inherited from Store

#options, #silence

Instance Method Summary collapse

Methods inherited from Store

#delete, #exist?, #fetch, #fetch_multi, instrument, instrument=, #mute, #read, #read_multi, #silence!, #write

Constructor Details

#initialize(options = nil) ⇒ MemoryStore



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# 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 Method Details

#cleanup(options = nil) ⇒ Object

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



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# 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) ⇒ Object



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# 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) ⇒ Object

Decrement an integer value in the cache.



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# 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) ⇒ Object



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# 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) ⇒ Object

Increment an integer value in the cache.



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# 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

#inspectObject

:nodoc:



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# File 'activesupport/lib/active_support/cache/memory_store.rb', line 115

def inspect # :nodoc:
  "<##{self.class.name} entries=#{@data.size}, size=#{@cache_size}, options=#{@options.inspect}>"
end

#prune(target_size, max_time = nil) ⇒ Object

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



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# 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?Boolean

Returns true if the cache is currently being pruned.



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# File 'activesupport/lib/active_support/cache/memory_store.rb', line 72

def pruning?
  @pruning
end

#synchronize(&block) ⇒ Object

Synchronize calls to the cache. This should be called wherever the underlying cache implementation is not thread safe.



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# File 'activesupport/lib/active_support/cache/memory_store.rb', line 121

def synchronize(&block) # :nodoc:
  @monitor.synchronize(&block)
end