This gem provides a promise-based parallel interface to dalli (memcached), based on IOPromise.


Add this line to your application's Gemfile:

gem 'iopromise-dalli'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install iopromise-dalli


The pattern for using IOPromise::Dalli is very similar to regular Dalli, except that everything returns promises, and the promises resolve to response objects that contain the value and exist? as separate control and data information.

require 'iopromise/dalli'

client ='localhost:11211')

promises = [
  client.set('another_key', 'something'),

promises << client.get('next_key').then do |response|
  # note that control (exist?) and data (value) are not mixed
  if response.exist?
    puts "#{response.key} exists with value #{response.value}"
    puts "#{response.key} does not exist"

# this will execute all 3 operations at the same time, similarly to an "mget",
# but not dependent on an explicit API, nor limited to just gets.


After checking out the repo, run bin/setup to install dependencies. Then, run bundle exec rake spec 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 the created tag, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.


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

Code of Conduct

Everyone interacting in the iopromise project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.