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.

MemoryStore is thread-safe.

Methods
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Constants
PER_ENTRY_OVERHEAD = 240
 
Class Public methods
new(options = nil)

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 21
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
cached_size(key, entry)

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 115
def cached_size(key, entry)
  key.to_s.bytesize + entry.size + PER_ENTRY_OVERHEAD
end
cleanup(options = nil)

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

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 43
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.

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 34
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.

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 85
def decrement(name, amount = 1, options = nil)
  modify_value(name, -amount, options)
end
delete_entry(key, options)

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 148
def delete_entry(key, options)
  synchronize do
    @key_access.delete(key)
    entry = @data.delete(key)
    @cache_size -= cached_size(key, entry) if entry
    !!entry
  end
end
delete_matched(matcher, options = nil)

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

Source: show | on GitHub 

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

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 80
def increment(name, amount = 1, options = nil)
  modify_value(name, amount, options)
end
modify_value(name, amount, options)

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 157
def modify_value(name, amount, options)
  synchronize do
    options = merged_options(options)
    if num = read(name, options)
      num = num.to_i + amount
      write(name, num, options)
      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.

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 56
    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

    # Returns true if the cache is currently being pruned.
    def pruning?
      @pruning
    end

    # Increment an integer value in the cache.
    def increment(name, amount = 1, options = nil)
      modify_value(name, amount, options)
    end

    # Decrement an integer value in the cache.
    def decrement(name, amount = 1, options = nil)
      modify_value(name, -amount, options)
    end

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

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

    # Synchronize calls to the cache. This should be called wherever the underlying cache implementation
    # is not thread safe.
    def synchronize(&block) # :nodoc:
      @monitor.synchronize(&block)
    end

    private

      PER_ENTRY_OVERHEAD = 240

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

      def read_entry(key, options)
        entry = @data[key]
        synchronize do
          if entry
            @key_access[key] = Time.now.to_f
          else
            @key_access.delete(key)
          end
        end
        entry
      end

      def write_entry(key, entry, options)
        entry.dup_value!
        synchronize do
          old_entry = @data[key]
          return false if @data.key?(key) && options[:unless_exist]
          if old_entry
            @cache_size -= (old_entry.size - entry.size)
          else
            @cache_size += cached_size(key, entry)
          end
          @key_access[key] = Time.now.to_f
          @data[key] = entry
          prune(@max_size * 0.75, @max_prune_time) if @cache_size > @max_size
          true
        end
      end

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

      def modify_value(name, amount, options)
        synchronize do
          options = merged_options(options)
          if num = read(name, options)
            num = num.to_i + amount
            write(name, num, options)
            num
          end
        end
      end
  end
end
pruning?()

Returns true if the cache is currently being pruned.

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 75
def pruning?
  @pruning
end
read_entry(key, options)

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 119
def read_entry(key, options)
  entry = @data[key]
  synchronize do
    if entry
      @key_access[key] = Time.now.to_f
    else
      @key_access.delete(key)
    end
  end
  entry
end
write_entry(key, entry, options)

Source: show | on GitHub 

# File activesupport/lib/active_support/cache/memory_store.rb, line 131
def write_entry(key, entry, options)
  entry.dup_value!
  synchronize do
    old_entry = @data[key]
    return false if @data.key?(key) && options[:unless_exist]
    if old_entry
      @cache_size -= (old_entry.size - entry.size)
    else
      @cache_size += cached_size(key, entry)
    end
    @key_access[key] = Time.now.to_f
    @data[key] = entry
    prune(@max_size * 0.75, @max_prune_time) if @cache_size > @max_size
    true
  end
end