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>

1 files changed, 32 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index c47839b001..7bfc377ff1 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,37 @@
 *Rails 3.0.0 [beta 4/release candidate] (unreleased)*
 
+* Harmonize the caching API and refactor the backends.  #4452 [Brian Durand]
+  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)
+
 * JSON: encode objects that don't have a native JSON representation using to_hash, if available, instead of instance_values (the old fallback) or to_s (other encoders' default). Encode BigDecimal and Regexp encode as strings to conform with other encoders. Try to transcode non-UTF-8 strings.  [Jeremy Kemper]