Class: ActiveSupport::Cache::MemcachedStore

Inherits:
Store
  • Object
show all
Includes:
DupLocalCache, Strategy::LocalCache
Defined in:
lib/active_support/cache/memcached_store.rb

Overview

A cache store implementation which stores data in Memcached: memcached.org/

MemcachedStore uses memcached gem as backend to connect to Memcached server.

MemcachedStore implements the Strategy::LocalCache strategy which implements an in-memory cache inside of a block.

Direct Known Subclasses

MemcachedSnappyStore

Defined Under Namespace

Modules: DupLocalCache Classes: Codec, DupLocalStore

Constant Summary collapse

ESCAPE_KEY_CHARS = 
/[\x00-\x20%\x7F-\xFF]/n

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*addresses, **options) ⇒ MemcachedStore

Returns a new instance of MemcachedStore.



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# File 'lib/active_support/cache/memcached_store.rb', line 64

def initialize(*addresses, **options)
  addresses = addresses.flatten
  options[:codec] ||= Codec.new
  @swallow_exceptions = true
  @swallow_exceptions = options.delete(:swallow_exceptions) if options.key?(:swallow_exceptions)

  if options.key?(:coder)
    raise ArgumentError, "ActiveSupport::Cache::MemcachedStore doesn't support custom coders"
  end

  # We don't use a coder, so we set it to nil so Active Support don't think we're using
  # a deprecated one.
  super(options.merge(coder: nil))

  if addresses.first.is_a?(Memcached)
    @connection = addresses.first
    raise "Memcached::Rails is no longer supported, "\
          "use a Memcached instance instead" if @connection.is_a?(Memcached::Rails)
  else
    mem_cache_options = options.dup
    servers = mem_cache_options.delete(:servers)
    UNIVERSAL_OPTIONS.each { |name| mem_cache_options.delete(name) }
    @connection = Memcached.new([*addresses, *servers], mem_cache_options)
  end
end

Instance Attribute Details

#read_only ⇒ Object

Returns the value of attribute read_only.



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# File 'lib/active_support/cache/memcached_store.rb', line 60

def read_only
  @read_only
end

#swallow_exceptions ⇒ Object

Returns the value of attribute swallow_exceptions.



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# File 'lib/active_support/cache/memcached_store.rb', line 60

def swallow_exceptions
  @swallow_exceptions
end

Instance Method Details

#append(name, value, options = nil) ⇒ Object 



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

def append(name, value, options = nil)
  return true if read_only
  options = merged_options(options)
  normalized_key = normalize_key(name, options)

  handle_exceptions(return_value_on_error: nil, on_miss: false, miss_exceptions: [Memcached::NotStored]) do
    instrument(:append, name) do
      @connection.append(normalized_key, value)
    end
    true
  end
end

#cas(name, options = nil) ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 134

def cas(name, options = nil)
  options = merged_options(options)
  key = normalize_key(name, options)
  payload = nil

  success = handle_exceptions(return_value_on_error: false) do
    instrument(:cas, name, options) do
      @connection.cas(key, expiration(options)) do |raw_value|
        entry = deserialize_entry(raw_value)
        value = yield entry.value
        break true if read_only
        payload = serialize_entry(Entry.new(value, **options), options)
      end
    end
    true
  end

  if success
    local_cache.write_entry(key, payload) if local_cache
  else
    local_cache.delete_entry(key) if local_cache
  end

  success
end

#cas_multi(*names, **options) ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 160

def cas_multi(*names, **options)
  return if names.empty?

  options = merged_options(options)
  keys_to_names = Hash[names.map { |name| [normalize_key(name, options), name] }]

  sent_payloads = nil

  handle_exceptions(return_value_on_error: false) do
    instrument(:cas_multi, names, options) do
      written_payloads = @connection.cas(keys_to_names.keys, expiration(options)) do |raw_values|
        values = {}

        raw_values.each do |key, raw_value|
          entry = deserialize_entry(raw_value)
          values[keys_to_names[key]] = entry.value unless entry.expired?
        end

        values = yield values

        break true if read_only

        serialized_values = values.map do |name, value|
          [normalize_key(name, options), serialize_entry(Entry.new(value, **options), options)]
        end

        sent_payloads = Hash[serialized_values]
      end

      if local_cache && sent_payloads
        sent_payloads.each_key do |key|
          if written_payloads.key?(key)
            local_cache.write_entry(key, written_payloads[key])
          else
            local_cache.delete_entry(key)
          end
        end
      end

      true
    end
  end
end

#clear(options = nil) ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 222

def clear(options = nil)
  ActiveSupport::Notifications.instrument("cache_clear.active_support", options || {}) do
    @connection.flush
  end
end

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

:nodoc:



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# File 'lib/active_support/cache/memcached_store.rb', line 213

def decrement(name, amount = 1, options = nil) # :nodoc:
  options = merged_options(options)
  handle_exceptions(return_value_on_error: nil) do
    instrument(:decrement, name, amount: amount) do
      @connection.decr(normalize_key(name, options), amount)
    end
  end
end

#delete ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 108

def delete(*)
  return true if read_only
  super
end

#exist? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_support/cache/memcached_store.rb', line 234

def exist?(*)
  !!super
end

#increment(name, amount = 1, options = nil) ⇒ Object

:nodoc:



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# File 'lib/active_support/cache/memcached_store.rb', line 204

def increment(name, amount = 1, options = nil) # :nodoc:
  options = merged_options(options)
  handle_exceptions(return_value_on_error: nil) do
    instrument(:increment, name, amount: amount) do
      @connection.incr(normalize_key(name, options), amount)
    end
  end
end

#read_multi(*names) ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 113

def read_multi(*names)
  options = names.extract_options!
  return {} if names.empty?

  options = merged_options(options)
  keys_to_names = Hash[names.map { |name| [normalize_key(name, options), name] }]
  values = {}

  handle_exceptions(return_value_on_error: {}) do
    instrument(:read_multi, names, options) do
      if raw_values = @connection.get(keys_to_names.keys)
        raw_values.each do |key, value|
          entry = deserialize_entry(value)
          values[keys_to_names[key]] = entry.value unless entry.expired?
        end
      end
    end
    values
  end
end

#reset ⇒ Object

:nodoc:



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# File 'lib/active_support/cache/memcached_store.rb', line 238

def reset #:nodoc:
  handle_exceptions(return_value_on_error: false) do
    @connection.reset
  end
end

#stats ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 228

def stats
  ActiveSupport::Notifications.instrument("cache_stats.active_support") do
    @connection.stats
  end
end

#write ⇒ Object 



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# File 'lib/active_support/cache/memcached_store.rb', line 103

def write(*)
  return true if read_only
  super
end