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Class: ActiveSupport::Cache::RedisCacheStore

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, Store
Instance Chain:
self, Strategy::LocalCache, Store
Inherits: ActiveSupport::Cache::Store
Defined in: activesupport/lib/active_support/cache/redis_cache_store.rb

Overview

Redis cache store.

Deployment note: Take care to use a *dedicated Redis cache* rather than pointing this at your existing Redis server. It won’t cope well with mixed usage patterns and it won’t expire cache entries by default.

Redis cache server setup guide: redis.io/topics/lru-cache

  • Supports vanilla Redis, hiredis, and Redis::Distributed.

  • Supports Memcached-like sharding across Redises with Redis::Distributed.

  • Fault tolerant. If the Redis server is unavailable, no exceptions are raised. Cache fetches are all misses and writes are dropped.

  • Local cache. Hot in-memory primary cache within block/middleware scope.

  • #read_multi and write_multi support for Redis mget/mset. Use Redis::Distributed 4.0.1+ for distributed mget support.

  • #delete_matched support for Redis KEYS globs.

Constant Summary

Store - Inherited

DEFAULT_CODER

Class Attribute Summary

Store - Inherited

.logger

Class Method Summary

Store - Inherited

.new

Creates a new cache.

Instance Attribute Summary

Store - Inherited

#logger, #options,
#silence?

Alias for Store#silence.

Instance Method Summary

Strategy::LocalCache - Included

#middleware

Middleware class can be inserted as a ::Rack handler to be local cache for the duration of request.
#with_local_cache

Use a local cache for the duration of block.

Store - Inherited

#cleanup

Cleanups the cache by removing expired entries.
#clear

Clears the entire cache.
#decrement

Decrements an integer value in the cache.
#delete

Deletes an entry in the cache.
#delete_matched

Deletes all entries with keys matching the pattern.
#delete_multi

Deletes multiple entries in the cache.
#exist?

Returns true if the cache contains an entry for the given key.
#fetch

Fetches data from the cache, using the given key.
#fetch_multi

Fetches data from the cache, using the given keys.
#increment

Increments an integer value in the cache.
#mute

Silences the logger within a block.
#read

Reads data from the cache, using the given key.
#read_multi

Reads multiple values at once from the cache.
#silence,
#silence!

Silences the logger.
#write

Writes the value to the cache, with the key.
#write_multi

::ActiveSupport::Cache Storage API to write multiple values at once.
#key_matcher

Adds the namespace defined in the options to a pattern designed to match keys.

Constructor Details

.new(namespace: nil, compress: true, compress_threshold: 1.kilobyte, coder: DEFAULT_CODER, expires_in: nil, race_condition_ttl: nil, error_handler: DEFAULT_ERROR_HANDLER, **redis_options) ⇒ RedisCacheStore

Creates a new Redis cache store.

Handles four options: :redis block, :redis instance, single :url string, and multiple :url strings.

Option  Class       Result
:redis  Proc    ->  options[:redis].call
:redis  Object  ->  options[:redis]
:url    String  ->  Redis.new(url: …)
:url    Array   ->  Redis::Distributed.new([{ url: … }, { url: … }, …])

No namespace is set by default. Provide one if the Redis cache server is shared with other apps: namespace: 'myapp-cache'.

Compression is enabled by default with a 1kB threshold, so cached values larger than 1kB are automatically compressed. Disable by passing compress: false or change the threshold by passing compress_threshold: 4.kilobytes.

No expiry is set on cache entries by default. Redis is expected to be configured with an eviction policy that automatically deletes least-recently or -frequently used keys when it reaches max memory. See redis.io/topics/lru-cache for cache server setup.

Race condition TTL is not set by default. This can be used to avoid “thundering herd” cache writes when hot cache entries are expired. See Store#fetch for more.

[ GitHub ] 

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 172



def initialize(namespace: nil, compress: true, compress_threshold: 1.kilobyte, coder: DEFAULT_CODER, expires_in: nil, race_condition_ttl: nil, error_handler: DEFAULT_ERROR_HANDLER, **redis_options)
  @redis_options = redis_options

  @max_key_bytesize = MAX_KEY_BYTESIZE
  @error_handler = error_handler

  super namespace: namespace,
    compress: compress, compress_threshold: compress_threshold,
    expires_in: expires_in, race_condition_ttl: race_condition_ttl,
    coder: coder
end


  







Class Attribute Details



  

    .supports_cache_versioning?  ⇒ Boolean  (readonly)
  



  

    

Advertise cache versioning support.


  





  


  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 70



def self.supports_cache_versioning?
  true
end


  







Instance Attribute Details



  

    #max_key_bytesize   (readonly)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 143



attr_reader :max_key_bytesize


  








  

    #redis_options   (readonly)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 142



attr_reader :redis_options


  







Instance Method Details



  

    #cleanup(options = nil)  
  



  

    

::ActiveSupport::Cache Store API implementation.



Removes expired entries. Handled natively by Redis least-recently-/ least-frequently-used expiry, so manual cleanup is not supported.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 304



def cleanup(options = nil)
  super
end


  








  

    #clear(options = nil)  
  



  

    

Clear the entire cache on all Redis servers. Safe to use on shared servers if the cache is namespaced.



Failsafe: Raises errors.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 312



def clear(options = nil)
  failsafe :clear do
    if namespace = merged_options(options)[:namespace]
      delete_matched "*", namespace: namespace
    else
      redis.with { |c| c.flushdb }
    end
  end
end


  








  

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



  

    

::ActiveSupport::Cache Store API implementation.



Decrement a cached value. This method uses the Redis decr atomic operator and can only be used on values written with the :raw option. Calling it on a value not stored with :raw will initialize that value to zero.



Failsafe: Raises errors.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 285



def decrement(name, amount = 1, options = nil)
  instrument :decrement, name, amount: amount do
    failsafe :decrement do
      options = merged_options(options)
      key = normalize_key(name, options)

      redis.with do |c|
        c.decrby(key, amount).tap do
          write_key_expiry(c, key, options)
        end
      end
    end
  end
end


  








  

    #delete_matched(matcher, options = nil)  
  



  

    

::ActiveSupport::Cache Store API implementation.



Supports Redis KEYS glob patterns:



h?llo matches hello, hallo and hxllo
h*llo matches hllo and heeeello
h[ae]llo matches hello and hallo, but not hillo
h[^e]llo matches hallo, hbllo, ... but not hello
h[a-b]llo matches hallo and hbllo



Use \ to escape special characters if you want to match them verbatim.



See redis.io/commands/KEYS for more.



Failsafe: Raises errors.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 233



def delete_matched(matcher, options = nil)
  instrument :delete_matched, matcher do
    unless String === matcher
      raise ArgumentError, "Only Redis glob strings are supported: #{matcher.inspect}"
    end
    redis.with do |c|
      pattern = namespace_key(matcher, options)
      cursor = "0"
      # Fetch keys in batches using SCAN to avoid blocking the Redis server.
      nodes = c.respond_to?(:nodes) ? c.nodes : [c]

      nodes.each do |node|
        begin
          cursor, keys = node.scan(cursor, match: pattern, count: SCAN_BATCH_SIZE)
          node.del(*keys) unless keys.empty?
        end until cursor == "0"
      end
    end
  end
end


  








  

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



  

    

::ActiveSupport::Cache Store API implementation.



Increment a cached value. This method uses the Redis incr atomic operator and can only be used on values written with the :raw option. Calling it on a value not stored with :raw will initialize that value to zero.



Failsafe: Raises errors.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 262



def increment(name, amount = 1, options = nil)
  instrument :increment, name, amount: amount do
    failsafe :increment do
      options = merged_options(options)
      key = normalize_key(name, options)

      redis.with do |c|
        c.incrby(key, amount).tap do
          write_key_expiry(c, key, options)
        end
      end
    end
  end
end


  








  

    #inspect  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 197



def inspect
  instance = @redis || @redis_options
  "#<#{self.class} options=#{options.inspect} redis=#{instance.inspect}>"
end


  








  

    #read_multi(*names)  
  



  

    

::ActiveSupport::Cache Store API implementation.



Read multiple values at once. Returns a hash of requested keys -> fetched values.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 206



def read_multi(*names)
  if mget_capable?
    instrument(:read_multi, names, options) do |payload|
      read_multi_mget(*names).tap do |results|
        payload[:hits] = results.keys
      end
    end
  else
    super
  end
end


  








  

    #redis  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 184



def redis
  @redis ||= begin
    pool_options = self.class.send(:retrieve_pool_options, redis_options)

    if pool_options.any?
      self.class.send(:ensure_connection_pool_added!)
      ::ConnectionPool.new(pool_options) { self.class.build_redis(**redis_options) }
    else
      self.class.build_redis(**redis_options)
    end
  end
end