Class: ActiveSupport::Cache::MemoryStore

Inherits:
Store show all
Includes:
Strategy::LocalCache
Defined in:
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 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.

Defined Under Namespace

Modules: DupCoder

Constant Summary

Constants inherited from Store

Store::DEFAULT_POOL_OPTIONS, Store::MAX_KEY_SIZE

Instance Attribute Summary

Attributes inherited from Store

#options, #silence

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Strategy::LocalCache

#fetch_multi, #local_cache, #middleware, #new_local_cache, #unset_local_cache, #with_local_cache

Methods inherited from Store

#delete, #delete_multi, #exist?, #fetch, #fetch_multi, #mute, #namespace, #namespace=, #new_entry, #read, #read_counter, #read_multi, #silence!, #write, #write_counter, #write_multi

Constructor Details

#initialize(options = nil) ⇒ MemoryStore

Returns a new instance of MemoryStore.



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# File 'lib/active_support/cache/memory_store.rb', line 75

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 Method Details

.supports_cache_versioning? ⇒ Boolean

Advertise cache versioning support.

Returns:

  • (Boolean) 


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# File 'lib/active_support/cache/memory_store.rb', line 90

def self.supports_cache_versioning?
  true
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 'lib/active_support/cache/memory_store.rb', line 103

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

Delete all data stored in a given cache store.



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# File 'lib/active_support/cache/memory_store.rb', line 95

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

#decrement(name, amount = 1, **options) ⇒ Object

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



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# File 'lib/active_support/cache/memory_store.rb', line 168

def decrement(name, amount = 1, **options)
  instrument(:decrement, name, amount: amount) do
    modify_value(name, -amount, **options)
  end
end

#delete_matched(matcher, options = nil) ⇒ Object

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



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# File 'lib/active_support/cache/memory_store.rb', line 175

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) ⇒ Object

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



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# File 'lib/active_support/cache/memory_store.rb', line 151

def increment(name, amount = 1, **options)
  instrument(:increment, name, amount: amount) do
    modify_value(name, amount, **options)
  end
end

#inspect ⇒ Object

:nodoc:



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

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 'lib/active_support/cache/memory_store.rb', line 116

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

#pruning? ⇒ Boolean

Returns true if the cache is currently being pruned.

Returns:

  • (Boolean) 


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# File 'lib/active_support/cache/memory_store.rb', line 135

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 'lib/active_support/cache/memory_store.rb', line 193

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