3 files changed, 169 insertions, 0 deletions
diff --git a/lib/killjoy/rmq/amqp_configuration.rb b/lib/killjoy/rmq/amqp_configuration.rb
new file mode 100644
index 0000000..62262f8
--- /dev/null
+++ b/lib/killjoy/rmq/amqp_configuration.rb
@@ -0,0 +1,47 @@
+module Killjoy
+  class AMQPConfiguration
+    attr_reader :environment
+
+    def initialize(environment: ENV.fetch("ENV", "development"))
+      @environment = environment
+    end
+
+    def amqp_uri
+      configuration['amqp_uri']
+    end
+
+    def heartbeat
+      configuration['heartbeat'].to_i
+    end
+
+    def prefetch
+      configuration['prefetch'].to_i
+    end
+
+    def exchange
+      configuration['exchange']
+    end
+
+    def exchange_type
+      configuration['exchange_type']
+    end
+
+    def shards
+      configuration['shards'].to_i
+    end
+
+    def to_hash
+      configuration
+    end
+
+    private
+
+    def configuration(file = "config/amqp.yml")
+      @configuration ||= YAML.load(expand_template(file))[environment]
+    end
+
+    def expand_template(file)
+      ERB.new(File.read(file)).result(binding)
+    end
+  end
+end
diff --git a/lib/killjoy/rmq/message.rb b/lib/killjoy/rmq/message.rb
new file mode 100644
index 0000000..2aa9c7d
--- /dev/null
+++ b/lib/killjoy/rmq/message.rb
@@ -0,0 +1,47 @@
+module Killjoy
+  class Message
+    attr_reader :to_hash, :info, :channel
+
+    def initialize(raw_message, info, channel)
+      @to_hash = JSON.parse(raw_message, symbolize_names: true)
+      @info = info
+      @channel = channel
+      @interceptors = { ack: [], reject: [] }
+    end
+
+    def intercept(response_type, &block)
+      @interceptors[response_type] << block
+    end
+
+    def process(future)
+      future.on_success do |rows|
+        ack!
+      end
+      future.on_failure do |error|
+        reject!
+      end
+    end
+
+    def ack!
+      run_interceptors_for(:ack)
+      channel.acknowledge(info.delivery_tag, false)
+    end
+
+    def reject!(requeue = false)
+      run_interceptors_for(:reject)
+      channel.reject(info.delivery_tag, requeue)
+    end
+
+    def to_s
+      to_hash
+    end
+
+    private
+
+    def run_interceptors_for(response_type)
+      @interceptors[response_type].each do |interceptor|
+        interceptor.call
+      end
+    end
+  end
+end
diff --git a/lib/killjoy/rmq/message_bus.rb b/lib/killjoy/rmq/message_bus.rb
new file mode 100644
index 0000000..710e4cd
--- /dev/null
+++ b/lib/killjoy/rmq/message_bus.rb
@@ -0,0 +1,75 @@
+module Killjoy
+  class MessageBus
+    attr_reader :configuration
+
+    def initialize(configuration = AMQPConfiguration.new)
+      @configuration = configuration
+      @subscriptions = Queue.new
+      @cpus = Facter.value('processors')['count'].to_i
+    end
+
+    def subscribe(consumer)
+      options = { manual_ack: true, block: false }
+      queue = create_queue(consumer)
+      subscription = queue.subscribe(options) do |info, metadata, raw_message|
+        begin
+          message = Message.new(raw_message, info, channel)
+          if block_given?
+            yield message
+          else
+            consumer.work(message)
+          end
+        rescue => error
+          Killjoy.logger.error(error.message)
+          message.reject!
+        end
+      end
+      @subscriptions << subscription
+    end
+
+    def stop
+      while @subscriptions.size > 0
+        @subscriptions.deq.cancel
+      end
+      connection.close
+    end
+
+    def publish(message)
+      message.publish_to(exchange)
+    end
+
+    private
+
+    def connection
+      @connection ||= Bunny.new(
+        configuration.amqp_uri,
+        heartbeat: configuration.heartbeat,
+        logger: Killjoy.logger
+      ).tap do |connection|
+        connection.start
+      end
+    end
+
+    def channel
+      @channel ||= connection.create_channel(nil, @cpus).tap do |x|
+        x.prefetch(configuration.prefetch)
+      end
+    end
+
+    def exchange
+      @exchange ||= channel.exchange(
+        configuration.exchange,
+        durable: true,
+        type: configuration.exchange_type
+      )
+    end
+
+    def create_queue(consumer)
+      queue = channel.queue(consumer.queue_name, exclusive: false, durable: true)
+      consumer.bindings.each do |binding|
+        queue.bind(exchange, routing_key: binding)
+      end
+      queue
+    end
+  end
+end