Merge pull request #14 from ninech/reuse_bunny_connection

Reuse an (existing) Bunny::Session in/with Cony

Author: cimnine

README.md

@@ -30,6 +30,17 @@ Cony.configure do |config|
 end
 ```
 
+### Using an existing Bunny connection
+
+You can share your already established `Bunny::Session` with Cony.
+
+```ruby
+Cony::AMQPConnection.instance.connection = your_connection
+```
+
+Cony will only accept the given connection if it's current connection is closed or if there is no current
+connection. There will be an error if Cony already has a connection!
+This restriction is imposed because else Cony might leak connections.
 
 ## Getting Started
 
@@ -64,7 +75,7 @@ The sent JSON structure will look like this:
     { "description": { "old": null, "new": "value" } }
   ],
   "event": "created",
-  "model": "Example::Model",
+  "model": "Example::Model"
 }
 ```
 
@@ -83,7 +94,7 @@ The sent JSON structure will look like this:
     { "name": { "old": "old-value", "new": "new-value" } }
   ],
   "event": "updated",
-  "model": "Example::Model",
+  "model": "Example::Model"
 }
 ```
 
@@ -102,7 +113,7 @@ The sent JSON structure will look like this:
     { "name": { "old": "value", "new": null } }
   ],
   "event": "destroyed",
-  "model": "Example::Model",
+  "model": "Example::Model"
 }
 ```
 

lib/cony.rb

@@ -9,6 +9,21 @@
 
 require 'cony/active_record'
 
+##
+# To configure Cony:
+# <code>
+# Cony.configure do |config|
+#   config.amqp = {
+#     host: 'localhost',
+#     exchange: 'organization.application',
+#     ssl: true,
+#     user: 'username',
+#     pass: 'secret',
+#   }
+#   config.test_mode = Rails.env.test?
+#   # config.durable = false
+# end
+# </code>
 module Cony
   include ActiveSupport::Configurable
 

lib/cony/active_record.rb

@@ -1,11 +1,19 @@
 require 'active_support/core_ext/string/inflections'
 
 require 'cony'
-require 'cony/amqp_connection_handler'
+require 'cony/amqp_connection'
 
 module Cony
+  ##
+  # Usage:
+  # <code>
+  # class FooBar < ActiveRecord::Base
+  #   include Cony::ActiveRecord
+  #   # your things here
+  # end
+  # </code>
+  #
   module ActiveRecord
-
     extend ActiveSupport::Concern
 
     included do
@@ -30,13 +38,11 @@ def cony_save_destroy_notify_data
 
     def cony_publish
       return if Cony.config.test_mode
-      cony_amqp_connection.publish(cony_notify_hash, cony_notify_routing_key)
+
+      Cony::AMQPConnection.publish(cony_notify_hash, cony_notify_routing_key)
     end
 
     private
-    def cony_amqp_connection
-      @cony_amqp_connection ||= Cony::AMQPConnectionHandler.new(Cony.config.amqp)
-    end
 
     def cony_mapped_changes
       changes.map do |name, change|

lib/cony/amqp_connection.rb

@@ -0,0 +1,68 @@
+require 'bunny'
+require 'json'
+require 'singleton'
+require 'cony/valid_connection_already_defined'
+
+module Cony
+  ##
+  # The only place in cony that deals with AMQP connection and it's lifecycle
+  class AMQPConnection
+    include Singleton
+
+    ##
+    # Shorthand for +Cony::AMQPConnection.instance.publish+
+    def self.publish(message, routing_key)
+      instance.publish(message, routing_key)
+    end
+
+    ##
+    # :category: Internal
+    # Sends the status change message to the configured AMQP destination
+    def publish(message, routing_key)
+      exchange.publish(message.to_json,
+                       key: routing_key,
+                       mandatory: false,
+                       immediate: false,
+                       persistent: Cony.config.durable,
+                       content_type: 'application/json')
+    rescue => error
+      Airbrake.notify(error) if defined? Airbrake
+      Rails.logger.error("#{error.class}: #{error}") if defined? Rails
+    end
+
+    ##
+    # Sets a custom connection if no valid_connection? is already provided
+    def connection=(connection)
+      fail Cony::ValidConnectionAlreadyDefined, 'A connection has already been set.' if valid_connection_present?
+      @connection = connection
+    end
+
+    ##
+    # Returns the existing connection or creates a new connection
+    def connection
+      return @connection if valid_connection_present?
+
+      @connection = Bunny.new Cony.config.amqp
+      ObjectSpace.define_finalizer(self, proc { cleanup })
+      @connection.start
+    end
+
+    ##
+    # +false+ if invalid_connection? is +true+
+    def valid_connection_present?
+      !@connection.nil? && @connection.open?
+    end
+
+    private
+
+    def exchange
+      connection.
+        create_channel.
+        topic(Cony.config.amqp[:exchange], durable: Cony.config.durable)
+    end
+
+    def cleanup
+      @connection.close if valid_connection_present?
+    end
+  end
+end

lib/cony/amqp_connection_handler.rb

@@ -0,0 +1,4 @@
+module Cony
+  class ValidConnectionAlreadyDefined < StandardError
+  end
+end

lib/cony/valid_connection_already_defined.rb

@@ -3,12 +3,11 @@
 require 'cony/active_record'
 
 describe Cony::ActiveRecord do
-
-  let(:amqp_connection) { double('Cony::AMQPConnectionHandler') }
+  let(:amqp_connection) { double('Cony::AMQPConnection') }
   let(:id) { 1337 }
-  let(:active_record_changes) { {name: ['old', 'new']} }
-  let(:active_record_attributes) { {name: 'value'} }
-  let(:cony_changes) { [{name: {old: 'old', new: 'new'}}] }
+  let(:active_record_changes) { { name: %w(old new) } }
+  let(:active_record_attributes) { { name: 'value' } }
+  let(:cony_changes) { [{ name: { old: 'old', new: 'new' } }] }
   let(:expected_payload) do
     {
       id: id,
@@ -36,7 +35,7 @@ def attributes; #{active_record_attributes}; end
   end
 
   before do
-    allow(Cony::AMQPConnectionHandler).to receive(:new).and_return(amqp_connection)
+    allow(Cony::AMQPConnection).to receive(:instance).and_return(amqp_connection)
   end
 
   subject { model.new }
@@ -61,7 +60,7 @@ def attributes; #{active_record_attributes}; end
 
   describe '#cony_send_destroy_notify' do
     let(:event) { :destroyed }
-    let(:cony_changes) { [{name: {old: 'value', new: nil}}] }
+    let(:cony_changes) { [{ name: { old: 'value', new: nil } }] }
     it 'uses the amqp connection to send the notify' do
       expect(amqp_connection).to receive(:publish).with(expected_payload, 'anonymaus/klass.mutation.destroyed')
       subject.cony_save_destroy_notify_data
@@ -74,10 +73,9 @@ def attributes; #{active_record_attributes}; end
       allow(Cony.config).to receive(:test_mode).and_return(true)
     end
     it 'does not send the message' do
-      expect(Cony::AMQPConnectionHandler).to_not receive(:new)
+      expect(Cony::AMQPConnection).to_not receive(:instance)
       subject.cony_save_create_notify_data
       subject.cony_publish
     end
   end
-
 end