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Class: ActiveSupport::Cache::MemoryStore

Relationships & Source Files
Namespace Children
Modules:
DupCoder
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Store
Instance Chain:
self, Store
Inherits: ActiveSupport::Cache::Store
Defined in: activesupport/lib/active_support/cache/memory_store.rb

Overview

Memory Cache Store

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 Phusion Passenger or puma clustered mode), 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.

Unlike other ::ActiveSupport::Cache store implementations, MemoryStore does not compress values by default. MemoryStore does not benefit from compression as much as other Store implementations, as it does not send data over a network. However, when compression is enabled, it still pays the full cost of compression in terms of cpu use.

MemoryStore is thread-safe.

Constant Summary

Store - Inherited

DEFAULT_POOL_OPTIONS

Class Attribute Summary

Store - Inherited

.logger, .raise_on_invalid_cache_expiration_time

Class Method Summary

Store - Inherited

.new

Creates a new cache.
.retrieve_pool_options

Instance Attribute Summary

Store - Inherited

#logger, #options, #raise_on_invalid_cache_expiration_time,
#silence?

Alias for Store#silence.

Instance Method Summary

Store - Inherited

#cleanup

Cleans up the cache by removing expired entries.
#clear

Clears the entire cache.
#decrement

Decrements an integer value in the cache.
#delete

Deletes an entry in the cache.
#delete_matched

Deletes all entries with keys matching the pattern.
#delete_multi

Deletes multiple entries in the cache.
#exist?

Returns true if the cache contains an entry for the given key.
#fetch

Fetches data from the cache, using the given key.
#fetch_multi

Fetches data from the cache, using the given keys.
#increment

Increments an integer value in the cache.
#mute

Silences the logger within a block.
#read

Reads data from the cache, using the given key.
#read_multi

Reads multiple values at once from the cache.
#silence,
#silence!

Silences the logger.
#write

Writes the value to the cache with the key.
#write_multi

::ActiveSupport::Cache Storage API to write multiple values at once.
#_instrument, #default_serializer,
#delete_entry

Deletes an entry from the cache implementation.
#delete_multi_entries

Deletes multiples entries in the cache implementation.
#deserialize_entry,
#expanded_key

Expands key to be a consistent string value.
#expanded_version, #get_entry_value, #handle_expired_entry, #handle_invalid_expires_in, #instrument, #instrument_multi,
#key_matcher

Adds the namespace defined in the options to a pattern designed to match keys.
#merged_options

Merges the default options with ones specific to a method call.
#namespace_key

Prefix the key with a namespace string:
#normalize_key

Expands and namespaces the cache key.
#normalize_options

Normalize aliased options to their canonical form.
#normalize_version,
#read_entry

Reads an entry from the cache implementation.
#read_multi_entries

Reads multiple entries from the cache implementation.
#save_block_result_to_cache, #serialize_entry, #validate_options,
#write_entry

Writes an entry to the cache implementation.
#write_multi_entries

Writes multiple entries to the cache implementation.
#new_entry

Constructor Details

.new(options = nil) ⇒ MemoryStore

[ GitHub ] 

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 73



def initialize(options = nil)
  options ||= {}
  options[:coder] = DupCoder unless options.key?(:coder) || options.key?(:serializer)
  # Disable compression by default.
  options[:compress] ||= false
  super(options)
  @data = {}
  @max_size = options[:size] || 32.megabytes
  @max_prune_time = options[:max_prune_time] || 2
  @cache_size = 0
  @monitor = Monitor.new
  @pruning = false
end


  







Class Attribute Details



  

    .supports_cache_versioning?  ⇒ Boolean  (readonly)
  



  

    

Advertise cache versioning support.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 88



def self.supports_cache_versioning?
  true
end


  







Instance Attribute Details



  

    #pruning?  ⇒ Boolean  (readonly)
  



  

    

Returns true if the cache is currently being pruned.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 133



def pruning?
  @pruning
end


  







Instance Method Details



  

    #cached_size(key, payload)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 194



def cached_size(key, payload)
  key.to_s.bytesize + payload.bytesize + PER_ENTRY_OVERHEAD
end


  








  

    #cleanup(options = nil)  
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 101



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)  
  



  

    

Delete all data stored in a given cache store.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 93



def clear(options = nil)
  synchronize do
    @data.clear
    @cache_size = 0
  end
end


  








  

    #decrement(name, amount = 1, options = nil)  
  



  

    

Decrement a cached integer value. Returns the updated value.



If the key is unset or has expired, it will be set to -amount.



cache.decrement("foo") # => -1



To set a specific value, call #write:



cache.write("baz", 5)
cache.decrement("baz") # => 4


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 164



def decrement(name, amount = 1, options = nil)
  modify_value(name, -amount, options)
end


  








  

    #delete_entry(key, **options)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 227



def delete_entry(key, **options)
  synchronize do
    payload = @data.delete(key)
    @cache_size -= cached_size(key, payload) if payload
    !!payload
  end
end


  








  

    #delete_matched(matcher, options = nil)  
  



  

    

Deletes cache entries if the cache key matches a given pattern.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 169



def delete_matched(matcher, options = nil)
  options = merged_options(options)
  matcher = key_matcher(matcher, options)

  instrument(:delete_matched, matcher.inspect) do
    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 a cached integer value. Returns the updated value.



If the key is unset, it will be set to amount:



cache.increment("foo") # => 1
cache.increment("bar", 100) # => 100



To set a specific value, call #write:



cache.write("baz", 5)
cache.increment("baz") # => 6


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 149



def increment(name, amount = 1, options = nil)
  modify_value(name, amount, options)
end


  








  

    #inspect  
  

  

    This method is for internal use only.
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 181



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


  








  

    #modify_value(name, amount, options)   (private)
  



  

    

Modifies the amount of an integer value that is stored in the cache. If the key is not found it is created and set to amount.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 237



def modify_value(name, amount, options)
  options = merged_options(options)
  key     = normalize_key(name, options)
  version = normalize_version(name, options)

  synchronize do
    entry = read_entry(key, **options)

    if !entry || entry.expired? || entry.mismatched?(version)
      write(name, Integer(amount), options)
      amount
    else
      num = entry.value.to_i + amount
      entry = Entry.new(num, expires_at: entry.expires_at, version: entry.version)
      write_entry(key, entry)
      num
    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.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 114



def prune(target_size, max_time = nil)
  return if pruning?
  @pruning = true
  begin
    start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC)
    cleanup
    instrument(:prune, target_size, from: @cache_size) do
      keys = synchronize { @data.keys }
      keys.each do |key|
        delete_entry(key, **options)
        return if @cache_size <= target_size || (max_time && Process.clock_gettime(Process::CLOCK_MONOTONIC) - start_time > max_time)
      end
    end
  ensure
    @pruning = false
  end
end


  








  

    #read_entry(key, **options)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 198



def read_entry(key, **options)
  entry = nil
  synchronize do
    payload = @data.delete(key)
    if payload
      @data[key] = payload
      entry = deserialize_entry(payload)
    end
  end
  entry
end


  








  

    #synchronize(&block)  
  

  

    This method is for internal use only.
  



  

    

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


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 187



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


  








  

    #write_entry(key, entry, **options)   (private)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/memory_store.rb', line 210



def write_entry(key, entry, **options)
  payload = serialize_entry(entry, **options)
  synchronize do
    return false if options[:unless_exist] && exist?(key, namespace: nil)

    old_payload = @data[key]
    if old_payload
      @cache_size -= (old_payload.bytesize - payload.bytesize)
    else
      @cache_size += cached_size(key, payload)
    end
    @data[key] = payload
    prune(@max_size * 0.75, @max_prune_time) if @cache_size > @max_size
    true
  end
end