A simple caching library that provides flexible and powerful caching features such as in-memory and file based caching similar to Guava's Caching system.

• Supports in-memory cache
• Supports filesystem based cache
• Limiting the size of the cache through eviction based on a specified max size
• Allows for expiration behavior based on the time since an object was placed in the cache or when it was last accessed/updated
• Allows custom refresh functions for reloading expensive data once it has been discarded

For an in memory Cache with an expiry time of 3 seconds, a max size of 500, and refresh method where 100 is added to the key (of course more sophisticated value retrieving operations will replace this method), and a function set_post_get which defines a function to be executed after the retrieval of a key. These additions are optional and configurable. The simplest form of an in-memory cache is CacheBuilder.with(Cache).build

cache = CacheBuilder.with(Cache).set_expiry('3s').set_max(500).set_refresh(lambda { |key| key + 100 }).set_post_get(lambda { |*key| puts "Retrieved #{key}!" }).build

...or for an file-based Cache with an expiry time of 3 seconds, store location at 'foo\bar', and refresh method where 100 is added to the key, and a function set_post_get which defines a function to be executed after the retrieval of a key. Of course these additions are optional and configurable. The only thing that is non-removable is the set_store method. The simplest form of a File cache is CacheBuilder.with(FileCache).set_store('foo\bar').build

cache = CacheBuilder.with(FileCache).set_store('foo\bar').set_expiry('3s').set_max(500).set_refresh(lambda { |key| key + 100 }).set_post_get(lambda { |*key| puts "Retrieved #{key}!" }).build

cache.put(1, 5)
cache.get(1) # will return 5, also prints "Retrieved [1]!" to the console, as per the function defined in the set_post_get method
sleep 4 # note that this is more than the expiry time
cache.get(1) # will return 105 as the data has been refreshed, also prints "Retrieved [1]!" 
cache.exists?(1) # will return true. if there is no set_refresh method provided then it will return false

cache.put("key123", [1,2,true])
pp cache.get("key123") # prints '[1, 2, true]' preserves type, prints "Retrieved ["key123"]!"

# delete all data on exit of program
# if the file cache was used, deletes all left over files. #cache.invalidate_all can be called at any point in runtime.
at_exit do
  cache.invalidate_all
end

For more on what kind of strings are understood as times, like "3s", click here.

Add this line to your application's Gemfile:

gem 'libcache'

And then execute:

$ bundle

Or install it yourself as:

$ gem install libcache

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/silk8192/libcache. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.