Class: ActiveSupport::Cache::MemoryStore

Inherits:
Store show all
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 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

Instance Attribute Summary

Attributes inherited from Store

#options, #silence

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Store

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

Constructor Details

#initialize(options = nil) ⇒ MemoryStore

Returns a new instance of MemoryStore.



73
74
75
76
77
78
79
80
81
82
83
84
85
 
# 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 Method Details

.supports_cache_versioning? ⇒ Boolean

Advertise cache versioning support.

Returns:

  • (Boolean) 


88
89
90
 
# File 'activesupport/lib/active_support/cache/memory_store.rb', line 88

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.



101
102
103
104
105
106
107
108
109
110
 
# 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) ⇒ Object

Delete all data stored in a given cache store.



93
94
95
96
97
98
 
# 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) ⇒ 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



164
165
166
 
# 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_matched(matcher, options = nil) ⇒ Object

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



169
170
171
172
173
174
175
176
177
178
 
# File 'activesupport/lib/active_support/cache/memory_store.rb', line 169

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 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



149
150
151
 
# 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 ⇒ Object

:nodoc:



180
181
182
 
# File 'activesupport/lib/active_support/cache/memory_store.rb', line 180

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.



114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
 
# 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

#pruning? ⇒ Boolean

Returns true if the cache is currently being pruned.

Returns:

  • (Boolean) 


133
134
135
 
# File 'activesupport/lib/active_support/cache/memory_store.rb', line 133

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.



186
187
188
 
# File 'activesupport/lib/active_support/cache/memory_store.rb', line 186

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