ConnectionPool adapter

Gemfile

@@ -28,6 +28,7 @@ gem 'mysql2'
 gem 'pg'
 gem 'cuprite'
 gem 'puma'
+gem 'connection_pool'
 
 group(:guard) do
  gem 'guard'

lib/flipper/adapter.rb

@@ -1,6 +1,20 @@
 module Flipper
  # Adding a module include so we have some hooks for stuff down the road
  module Adapter
+ OPERATIONS = [
+ :add,
+ :clear,
+ :disable,
+ :enable,
+ :export,
+ :features,
+ :get_all,
+ :get_multi,
+ :get,
+ :import,
+ :remove,
+ ]
+
  def self.included(base)
  base.extend(ClassMethods)
  end

lib/flipper/adapters/connection_pool.rb

@@ -0,0 +1,76 @@
+require "connection_pool"
+require "observer"
+
+# Make ConnectionPool observable so we can reset the cache when the pool is reloaded or shutdown
+ConnectionPool.class_eval do
+ module ShutdownObservable
+ def reload(&block)
+ super(&block).tap do
+ changed
+ notify_observers
+ end
+ end
+
+ def shutdown(&block)
+ super(&block).tap do
+ changed
+ notify_observers
+ end
+ end
+ end
+
+ include Observable
+ prepend ShutdownObservable
+end
+
+# An adapter that uses ConnectionPool to manage connections.
+#
+# Usage:
+#
+# # Reuse an existing pool to create new adapters
+# pool = ConnectionPool.new(size: 5, timeout: 5) { Redis.new }
+# Flipper::Adapters::ConnectionPool.new(pool) do |client|
+# Flipper::Adapters::Redis.new(client)
+# end
+#
+# # Create a new pool that returns the adapter
+# Flipper::Adapters::ConnectionPool.new(size: 5, timeout: 5) do
+# Flipper::Adapters::Redis.new(Redis.new)
+# end
+class Flipper::Adapters::ConnectionPool
+ include Flipper::Adapter
+
+ # Use an existing ConnectionPool to initialize and cache new adapter instances.
+ class Wrapper
+ def initialize(pool, &initializer)
+ @pool = pool
+ @initializer = initializer
+ @instances = {}
+
+ # Reset the cache when the pool is reloaded or shutdown
+ @pool.add_observer(self, :reset)
+ end
+
+ def with(&block)
+ @pool.with do |resource|
+ yield @instances[resource] ||= @initializer.call(resource)
+ end
+ end
+
+ def reset
+ @instances.clear
+ end
+ end
+
+ attr_reader :pool
+
+ def initialize(options = {}, &adapter_initializer)
+ @pool = options.is_a?(ConnectionPool) ? Wrapper.new(options, &adapter_initializer) : ConnectionPool.new(options, &adapter_initializer)
+ end
+
+ OPERATIONS.each do |method|
+ define_method(method) do |*args|
+ @pool.with { |adapter| adapter.public_send(method, *args) }
+ end
+ end
+end

spec/flipper/adapters/connection_pool_spec.rb

@@ -0,0 +1,40 @@
+require "connection_pool"
+require "flipper/adapters/connection_pool"
+require "flipper-redis"
+
+RSpec.describe Flipper::Adapters::ConnectionPool do
+ let(:redis_options) { {url: ENV['REDIS_URL']}.compact }
+
+ before do
+ skip_on_error(Redis::CannotConnectError, 'Redis not available') do
+ Redis.new(redis_options).flushdb
+ end
+ end
+
+ context "with an existing pool" do
+ let(:pool) do
+ ConnectionPool.new(size: 1, timeout: 5) { Redis.new(redis_options) }
+ end
+
+ subject do
+ described_class.new(pool) { |client| Flipper::Adapters::Redis.new(client) }
+ end
+
+ it_should_behave_like 'a flipper adapter'
+
+ it "should reset the cache when the pool is reloaded or shutdown" do
+ subject.get_all
+ expect { pool.reload { |_| } }.to change { subject.pool.instance_variable_get(:@instances).size }.from(1).to(0)
+ subject.get_all
+ expect { pool.shutdown { |_| } }.to change { subject.pool.instance_variable_get(:@instances).size }.from(1).to(0)
+ end
+ end
+
+ context "with a new pool" do
+ subject do
+ described_class.new(size: 2) { Flipper::Adapters::Redis.new(Redis.new(redis_options)) }
+ end
+
+ it_should_behave_like 'a flipper adapter'
+ end
+end