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Changeset [ee51b51b60f9e6cce9babed2c8a65a14d87790c8] by Brian Durand

April 27th, 2010 @ 07:13 PM

ActiveSupport::Cache refactoring

All Caches

  • Add default options to initializer that will be sent to all read, write, fetch, exist?, increment, and decrement
  • Add support for the :expires_in option to fetch and write for all caches. Cache entries are stored with the create timestamp and a ttl so that expiration can be handled independently of the implementation.
  • Add support for a :namespace option. This can be used to set a global prefix for cache entries.
  • Deprecate expand_cache_key on ActiveSupport::Cache and move it to ActionController::Caching and ActionDispatch::Http::Cache since the logic in the method used some Rails specific environment variables and was only used by ActionPack classes. Not very DRY but there didn't seem to be a good shared spot and ActiveSupport really shouldn't be Rails specific.
  • Add support for :race_condition_ttl to fetch. This setting can prevent race conditions on fetch calls where several processes try to regenerate a recently expired entry at once.
  • Add support for :compress option to fetch and write which will compress any data over a configurable threshold.
  • Nil values can now be stored in the cache and are distinct from cache misses for fetch.
  • Easier API to create new implementations. Just need to implement the methods read_entry, write_entry, and delete_entry instead of overwriting existing methods.
  • Since all cache implementations support storing objects, update the docs to state that ActiveCache::Cache::Store implementations should store objects. Keys, however, must be strings since some implementations require that.
  • Increase test coverage.
  • Document methods which are provided as convenience but which may not be universally available.


  • MemoryStore can now safely be used as the cache for single server sites.
  • Make thread safe so that the default cache implementation used by Rails is thread safe. The overhead is minimal and it is still the fastest store available.
  • Provide :size initialization option indicating the maximum size of the cache in memory (defaults to 32Mb).
  • Add prune logic that removes the least recently used cache entries to keep the cache size from exceeding the max.
  • Deprecated SynchronizedMemoryStore since it isn't needed anymore.


  • Escape key values so they will work as file names on all file systems, be consistent, and case sensitive
  • Use a hash algorithm to segment the cache into sub directories so that a large cache doesn't exceed file system limits.
  • FileStore can be slow so implement the LocalCache strategy to cache reads for the duration of a request.
  • Add cleanup method to keep the disk from filling up with expired entries.
  • Fix increment and decrement to use file system locks so they are consistent between processes.


  • Support all keys. Previously keys with spaces in them would fail
  • Deprecate CompressedMemCacheStore since it isn't needed anymore (use :compress => true)

[#4452 state:committed]

Signed-off-by: Jeremy Kemper

Committed by Brian Durand

  • M activesupport/CHANGELOG
  • M activesupport/lib/active_support/cache.rb
  • M activesupport/lib/active_support/cache/compressed_mem_cache_store.rb
  • M activesupport/lib/active_support/cache/file_store.rb
  • M activesupport/lib/active_support/cache/mem_cache_store.rb
  • M activesupport/lib/active_support/cache/memory_store.rb
  • M activesupport/lib/active_support/cache/strategy/local_cache.rb
  • M activesupport/lib/active_support/cache/synchronized_memory_store.rb
  • M activesupport/test/caching_test.rb

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