Extracted logging code from Travis.

Not fully tested yet.

.rspec

@@ -0,0 +1,2 @@
+--color
+--format progress

Guardfile

@@ -0,0 +1,9 @@
+# A sample Guardfile
+# More info at https://github.com/guard/guard#readme
+
+guard 'rspec', :version => 2 do
+  watch(%r{^spec/.+_spec\.rb$})
+  watch(%r{^lib/(.+)\.rb$})     { |m| "spec/lib/#{m[1]}_spec.rb" }
+  watch('spec/spec_helper.rb')  { "spec" }
+end
+

lib/lograge.rb

@@ -3,6 +3,25 @@
 
 module Lograge
   mattr_accessor :logger  
+
+  def self.remove_existing_log_subscriptions
+    %w(redirect_to process_action start_processing send_data write_fragment exist_fragment? send_file).each do |event|
+      ActiveSupport::Notifications.notifier.listeners_for("#{event}.action_controller").each do |listener|
+        if listener.inspect =~ /delegate[^a-z]+ActionController/
+          ActiveSupport::Notifications.unsubscribe listener
+        end
+      end
+
+    end
+
+    %w{render_template render_partial render_collection}.each do |event|
+      ActiveSupport::Notifications.notifier.listeners_for("#{event}.action_view").each do |listener|
+        if listener.inspect =~ /delegate[^a-z]+ActionView/
+          ActiveSupport::Notifications.unsubscribe listener
+        end
+      end
+    end
+  end
 end
 
 require 'lograge/railtie' if defined? Rails::Railtie

lib/lograge/log_subscriber.rb

@@ -0,0 +1,41 @@
+require 'active_support/core_ext/class/attribute'
+require 'active_support/log_subscriber'
+
+module Lograge
+  class LogSubscriber < ActiveSupport::LogSubscriber
+    class_attribute :logger
+
+    def initialize
+      self.logger ||= ActionController::Base.logger
+    end
+
+    def process_action(event)
+      payload = event.payload
+      message = "#{payload[:method]} #{payload[:path]} format=#{payload[:format]} action=#{payload[:params]['controller']}##{payload[:params]['action']}"
+      message << extract_status(payload)
+      message << runtimes(event)
+      logger.info(message)
+    end
+
+    private
+
+    def extract_status(payload)
+      if payload[:status]
+        " status=#{payload[:status]}"
+      elsif payload[:exception]
+        exception, message = payload[:exception]
+        " status=500 error='#{exception}:#{message}'"
+      end
+    end
+
+    def runtimes(event)
+      message = ""
+      {:duration => event.duration,
+       :view => event.payload[:view_runtime],
+       :db => event.payload[:db_runtime]}.each do |name, runtime|
+        message << " #{name}=%.2f" % runtime if runtime
+      end
+      message
+    end
+  end
+end

lib/lograge/railtie.rb

@@ -1,6 +1,11 @@
 require 'rails/railtie'
+require 'lograge/log_subscriber'
 
 module Lograge
   class Railtie < Rails::Railtie
+    initializer :lograge do |app|
+      Lograge.remove_existing_log_subscriptions
+      Lograge::LogSubscriber.attach_to 
+    end
   end
 end

lograge.gemspec

@@ -20,5 +20,7 @@ Gem::Specification.new do |s|
 
   # specify any dependencies here; for example:
   s.add_development_dependency "rspec"
+  s.add_development_dependency "guard-rspec"
   s.add_runtime_dependency "activesupport"
+  s.add_runtime_dependency "actionpack"
 end

spec/lograge_spec.rb

@@ -0,0 +1,40 @@
+require 'spec_helper'
+require 'lograge'
+require 'active_support/notifications'
+require 'active_support/core_ext/string'
+require 'active_support/log_subscriber'
+require 'action_controller/log_subscriber'
+require 'action_view/log_subscriber'
+
+describe Lograge do
+  describe "when removing Rails' log subscribers" do
+    after do
+      ActionController::LogSubscriber.attach_to :action_controller
+      ActionView::LogSubscriber.attach_to :action_view
+    end
+
+    it "should remove subscribers for controller events" do
+      expect {
+        Lograge.remove_existing_log_subscriptions
+      }.to change {
+        ActiveSupport::Notifications.notifier.listeners_for('process_action.action_controller')
+      }
+    end
+
+    it "should remove subscribers for all events" do
+      expect {
+        Lograge.remove_existing_log_subscriptions
+      }.to change {
+        ActiveSupport::Notifications.notifier.listeners_for('render_template.action_view')
+      }
+    end
+
+    it "shouldn't remove subscribers that aren't from Rails" do
+      blk = -> {}
+      ActiveSupport::Notifications.subscribe("process_action.action_controller", &blk)
+      Lograge.remove_existing_log_subscriptions
+      listeners = ActiveSupport::Notifications.notifier.listeners_for('process_action.action_controller')
+      listeners.size.should > 0
+    end
+  end
+end

spec/spec_helper.rb

@@ -0,0 +1,11 @@
+# This file was generated by the `rspec --init` command. Conventionally, all
+# specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
+# Require this file using `require "spec_helper.rb"` to ensure that it is only
+# loaded once.
+#
+# See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
+RSpec.configure do |config|
+  config.treat_symbols_as_metadata_keys_with_true_values = true
+  config.run_all_when_everything_filtered = true
+  config.filter_run :focus
+end