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 `::Object` ActiveSupport::Cache::Store ActiveSupport::Cache::RedisCacheStore
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 a persistent Redis server (for example, one used as an Active Job queue). Redis 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

DEFAULT_ERROR_HANDLER =
# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 47

#=> (method:, returning:, exception:) do
  if logger
    logger.error { "RedisCacheStore: #{method} failed, returned #{returning.inspect}: #{exception.class}: #{exception.message}" }
  end
  ActiveSupport.error_reporter&.report(
    exception,
    severity: :warning,
    source: "redis_cache_store.active_support",
  )
end

DEFAULT_REDIS_OPTIONS =
# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 41

{
  connect_timeout:    1,
  read_timeout:       1,
  write_timeout:      1,
}

MAX_KEY_BYTESIZE =

Keys are truncated with the Active Support digest if they exceed 1kB

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 39
```
1024
```
SCAN_BATCH_SIZE = private

The maximum number of entries to receive per SCAN call.

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 59
```
1000
```

`Store` - Inherited

DEFAULT_POOL_OPTIONS

Class Attribute Summary

.supports_cache_versioning? ⇒ Boolean readonly

Advertise cache versioning support.

`Store` - Inherited

.logger, .raise_on_invalid_cache_expiration_time

Class Method Summary

.new(error_handler: DEFAULT_ERROR_HANDLER, **redis_options) ⇒ RedisCacheStore constructor

Creates a new Redis cache store.

`Store` - Inherited

.new	Creates a new cache.

Instance Attribute Summary

#max_key_bytesize readonly
#redis readonly

`Store` - Inherited

#logger, #options, #raise_on_invalid_cache_expiration_time,
#silence?	Alias for Store#silence.

Instance Method Summary

#cleanup(options = nil)

::ActiveSupport::Cache Store API implementation.
#clear(options = nil)

Clear the entire cache on all Redis servers.
#decrement(name, amount = 1, options = nil)

Decrement a cached integer value using the Redis decrby atomic operator.
#delete_matched(matcher, options = nil)

::ActiveSupport::Cache Store API implementation.
#increment(name, amount = 1, options = nil)

Increment a cached integer value using the Redis incrby atomic operator.
#inspect
#read_multi(*names)

::ActiveSupport::Cache Store API implementation.
#stats

Get info from redis servers.

`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	Cleans up 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(error_handler: DEFAULT_ERROR_HANDLER, **redis_options) ⇒ `RedisCacheStore`

Creates a new Redis cache store.

There are four ways to provide the Redis client used by the cache: the :redis param can be a Redis instance or a block that returns a Redis instance, or the :url param can be a string or an array of strings which will be used to create a Redis instance or a Redis::Distributed instance.

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.

Setting skip_nil: true will not cache nil results:

cache.fetch('foo') { nil }
cache.fetch('bar', skip_nil: true) { nil }
cache.exist?('foo') # => true
cache.exist?('bar') # => false

[ GitHub ]

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 149


def initialize(error_handler: DEFAULT_ERROR_HANDLER, **redis_options)
  universal_options = redis_options.extract!(*UNIVERSAL_OPTIONS)

  if pool_options = self.class.send(:retrieve_pool_options, redis_options)
    @redis = ::ConnectionPool.new(pool_options) { self.class.build_redis(**redis_options) }
  else
    @redis = self.class.build_redis(**redis_options)
  end

  @max_key_bytesize = MAX_KEY_BYTESIZE
  @error_handler = error_handler

  super(universal_options)
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 63


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 109


attr_reader :max_key_bytesize

#redis (readonly)

[ GitHub ]

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 110


attr_reader :redis

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 276


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 284


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

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

Decrement a cached integer value using the Redis decrby atomic operator. 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 passing raw: true:

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

Decrementing a non-numeric value, or a value written without raw: true, will fail and return nil.

Failsafe: Raises errors.

[ GitHub ]

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


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)
      change_counter(key, -amount, options)
    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 198


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.then 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)

Increment a cached integer value using the Redis incrby atomic operator. Returns the updated value.

If the key is unset or has expired, it will be set to amount:

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

To set a specific value, call #write passing raw: true:

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

Incrementing a non-numeric value, or a value written without raw: true, will fail and return nil.

Failsafe: Raises errors.

[ GitHub ]

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 236


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)
      change_counter(key, amount, options)
    end
  end
end

#inspect

[ GitHub ]

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 164


def inspect
  "#<#{self.class} options=#{options.inspect} redis=#{redis.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 172


def read_multi(*names)
  return {} if names.empty?

  options = names.extract_options!
  instrument_multi(:read_multi, names, options) do |payload|
    read_multi_entries(names, **options).tap do |results|
      payload[:hits] = results.keys
    end
  end
end

#stats

Get info from redis servers.

[ GitHub ]

# File 'activesupport/lib/active_support/cache/redis_cache_store.rb', line 295


def stats
  redis.then { |c| c.info }
end

Class: ActiveSupport::Cache::RedisCacheStore

Overview

Redis Cache Store

Constant Summary

Store - Inherited

Class Attribute Summary

Store - Inherited

Class Method Summary

Store - Inherited

Instance Attribute Summary

Store - Inherited

Instance Method Summary

Strategy::LocalCache - Included

Store - Inherited

Constructor Details

.new(error_handler: DEFAULT_ERROR_HANDLER, **redis_options) ⇒ RedisCacheStore

Class Attribute Details

.supports_cache_versioning? ⇒ Boolean (readonly)

Instance Attribute Details

#max_key_bytesize (readonly)

#redis (readonly)

Instance Method Details

#cleanup(options = nil)

#clear(options = nil)

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

#delete_matched(matcher, options = nil)

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

#inspect

#read_multi(*names)

#stats

`Store` - Inherited

`Store` - Inherited

`Store` - Inherited

`Store` - Inherited

`Strategy::LocalCache` - Included

`Store` - Inherited

.new(error_handler: DEFAULT_ERROR_HANDLER, **redis_options) ⇒ `RedisCacheStore`

.supports_cache_versioning? ⇒ `Boolean` (readonly)