Rails Ruby on Rails

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

• 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.

FileStore

• 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.

MemCacheStore

• 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 jeremy@bitsweat.net
http://github.com/rails/rails/commit/ee51b51b60f9e6cce9babed2c8a65a...