class ActiveSupport::Cache::MemoryStore

MemoryStore is thread-safe.
compression in terms of cpu use.
However, when compression is enabled, it still pays the full cost of
as other Store implementations, as it does not send data over a network.
values by default. MemoryStore does not benefit from compression as much
Unlike other Cache store implementations, MemoryStore does not compress
of the maximum size by removing the least recently used entries.
a cleanup will occur which tries to prune the cache down to three quarters
initializer (default is 32Mb). When the cache exceeds the allotted size,
This cache has a bounded size specified by the :size options to the
appropriate cache in that scenario.
to share cache data with each other and this may not be the most
then this means that Rails server process instances won’t be able
(which is the case if you’re using Phusion Passenger or puma clustered mode),
same process. If you’re running multiple Ruby on Rails server processes
A cache store implementation which stores everything into memory in the
= Memory Cache Store

def self.supports_cache_versioning?

Advertise cache versioning support. 
def self.supports_cache_versioning?
  true
end

def cached_size(key, payload) 

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

def cleanup(options = nil)

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

def clear(options = nil)

Delete all data stored in a given cache store. 
def clear(options = nil)
  synchronize do
    @data.clear
    @cache_size = 0
  end
end

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


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

To set a specific value, call #write:

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

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

Decrement a cached integer value. Returns the updated value. 
def decrement(name, amount = 1, options = nil)
  modify_value(name, -amount, options)
end

def delete_entry(key, **options) 

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

def delete_matched(matcher, options = nil)

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 increment(name, amount = 1, options = nil)


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

To set a specific value, call #write:

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

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

Increment a cached integer value. Returns the updated value. 
def increment(name, amount = 1, options = nil)
  modify_value(name, amount, options)
end

def initialize(options = nil) 

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

def inspect # :nodoc:

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

def modify_value(name, amount, options)

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

def prune(target_size, max_time = nil)

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

def pruning?

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

def read_entry(key, **options) 

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

def synchronize(&block) # :nodoc:

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

def write_entry(key, entry, **options) 

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