Dalli 3.0

This major version update contains several backwards incompatible changes.

:dalli_store has been removed. Users should migrate to the official Rails :mem_cache_store, documented in the caching guide. Note that :mem_cache_store does not check for ENV['MEMCACHE_SERVERS'] prior to Rails 6.1, so you may need to explicitly provide it.
Attempting to store a larger value than allowed by memcached used to print a warning and truncate the value. This now raises an error to prevent silent data corruption.
Compression now defaults to true for large values (greater than 4KB). This is intended to minimize errors due to the previous note.
Errors marshalling values now raise rather than just printing an error.
The Rack session adapter has been refactored to remove support for thread-unsafe configurations. You will need to include the connection_pool gem in your Gemfile to ensure session operations are thread-safe.
Support for the kgio gem has been removed, it is not relevant in Ruby 2.3+.
Removed inline native code, use Ruby 2.3+ support for bsearch instead.
The CAS operations previously in 'dalli/cas/client' have been integrated into 'dalli/client'.

Future Directions

The memcached project has deprecated the binary protocol used by Dalli in favor of a new meta/text protocol that is somewhat human readable.

Dalli 4.0 will move in this direction and require memcached 1.6+.