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-rw-r--r--railties/lib/rails/subscriber.rb96
-rw-r--r--railties/test/subscriber_test.rb102
2 files changed, 198 insertions, 0 deletions
diff --git a/railties/lib/rails/subscriber.rb b/railties/lib/rails/subscriber.rb
new file mode 100644
index 0000000000..f98dec738d
--- /dev/null
+++ b/railties/lib/rails/subscriber.rb
@@ -0,0 +1,96 @@
+require 'active_support/core_ext/class/inheritable_attributes'
+require 'active_support/notifications'
+
+module Rails
+ # Rails::Subscriber is an object set to consume ActiveSupport::Notifications
+ # on initialization with solely purpose of logging. The subscriber dispatches
+ # notifications to a regirested object based on its given namespace.
+ #
+ # An example would be ActiveRecord subscriber responsible for logging queries:
+ #
+ # module ActiveRecord
+ # class Railtie
+ # class Subscriber < Rails::Subscriber
+ # def sql(event)
+ # "#{event.payload[:name]} (#{event.duration}) #{event.payload[:sql]}"
+ # end
+ # end
+ # end
+ # end
+ #
+ # It's finally registed as:
+ #
+ # Rails::Subscriber.add :active_record, ActiveRecord::Railtie::Subscriber.new
+ #
+ # So whenever a "active_record.sql" notification arrive to Rails::Subscriber,
+ # it will properly dispatch the event (ActiveSupport::Notifications::Event) to
+ # the sql method.
+ #
+ # This is useful because it avoids spanning several subscribers just for logging
+ # purposes(which slows down the main thread). Besides of providing a centralized
+ # facility on top of Rails.logger.
+ #
+ # Finally, Subscriber some helpers to deal with logging, like managing console colors.
+ class Subscriber
+ cattr_accessor :colorize_logging, :instance_writer => false
+ self.colorize_logging = true
+
+ # Embed in a String to clear all previous ANSI sequences.
+ CLEAR = "\e[0m"
+ BOLD = "\e[1m"
+
+ # Colors
+ BLACK = "\e[30m"
+ RED = "\e[31m"
+ GREEN = "\e[32m"
+ YELLOW = "\e[33m"
+ BLUE = "\e[34m"
+ MAGENTA = "\e[35m"
+ CYAN = "\e[36m"
+ WHITE = "\e[37m"
+
+ def self.add(namespace, subscriber)
+ subscribers[namespace.to_sym] = subscriber
+ end
+
+ def self.subscribers
+ @subscribers ||= {}
+ end
+
+ def self.dispatch(args)
+ namespace, name = args[0].split(".")
+ subscriber = subscribers[namespace.to_sym]
+
+ if subscriber.respond_to?(name) && subscriber.logger
+ subscriber.send(name, ActiveSupport::Notifications::Event.new(*args))
+ end
+ end
+
+ # By default, we use the Rails.logger for logging.
+ def logger
+ Rails.logger
+ end
+
+ protected
+
+ %w(info debug warn error fatal unknown).each do |level|
+ class_eval <<-METHOD, __FILE__, __LINE__ + 1
+ def #{level}(*args, &block)
+ logger.#{level}(*args, &block)
+ end
+ METHOD
+ end
+
+ # Set color by using a string or one of the defined constants. If a third
+ # option is set to true, it also adds bold to the string. This is based
+ # on Highline implementation and it automatically appends CLEAR to the end
+ # of the returned String.
+ #
+ def color(text, color, bold=false)
+ return text unless colorize_logging
+ color = self.class.const_get(color.to_s.upcase) if color.is_a?(Symbol)
+ bold = bold ? BOLD : ""
+ "#{bold}#{color}#{text}#{CLEAR}"
+ end
+ end
+end \ No newline at end of file
diff --git a/railties/test/subscriber_test.rb b/railties/test/subscriber_test.rb
new file mode 100644
index 0000000000..ada40e2d2b
--- /dev/null
+++ b/railties/test/subscriber_test.rb
@@ -0,0 +1,102 @@
+require 'abstract_unit'
+require 'rails/subscriber'
+
+Thread.abort_on_exception = true
+
+class MockLogger
+ def initialize
+ @logged = Hash.new { |h,k| h[k] = [] }
+ end
+
+ def method_missing(level, message)
+ @logged[level] << message
+ end
+
+ def logged(level)
+ @logged[level].compact.map { |l| l.to_s.strip }
+ end
+end
+
+ActiveSupport::Notifications.subscribe do |*args|
+ Rails::Subscriber.dispatch(args)
+end
+
+class MySubscriber < Rails::Subscriber
+ def some_event(event)
+ info event.name
+ end
+
+ def foo(event)
+ debug "debug"
+ info "info"
+ warn "warn"
+ end
+
+ def bar(event)
+ info "#{color("cool", :red)}, #{color("isn't it?", :blue, true)}"
+ end
+end
+
+class SubscriberTest < ActiveSupport::TestCase
+ def setup
+ @logger = MockLogger.new
+ @previous_logger, Rails.logger = Rails.logger, @logger
+ @subscriber = MySubscriber.new
+ wait
+ end
+
+ def teardown
+ Rails.logger = @previous_logger
+ Rails::Subscriber.subscribers.clear
+ end
+
+ def instrument(*args, &block)
+ ActiveSupport::Notifications.instrument(*args, &block)
+ end
+
+ def wait
+ ActiveSupport::Notifications.notifier.wait
+ end
+
+ def test_proxies_method_to_rails_logger
+ @subscriber.foo(nil)
+ assert_equal %w(debug), @logger.logged(:debug)
+ assert_equal %w(info), @logger.logged(:info)
+ assert_equal %w(warn), @logger.logged(:warn)
+ end
+
+ def test_set_color_for_messages
+ @subscriber.bar(nil)
+ assert_equal "\e[31mcool\e[0m, \e[1m\e[34misn't it?\e[0m", @logger.logged(:info).last
+ end
+
+ def test_does_not_set_color_if_colorize_logging_is_set_to_false
+ Rails::Subscriber.colorize_logging = false
+ @subscriber.bar(nil)
+ assert_equal "cool, isn't it?", @logger.logged(:info).last
+ ensure
+ Rails::Subscriber.colorize_logging = true
+ end
+
+ def test_event_is_sent_to_the_registered_class
+ Rails::Subscriber.add :my_subscriber, @subscriber
+ instrument "my_subscriber.some_event"
+ wait
+ assert_equal %w(my_subscriber.some_event), @logger.logged(:info)
+ end
+
+ def test_does_not_send_the_event_if_it_doesnt_match_the_class
+ Rails::Subscriber.add :my_subscriber, @subscriber
+ instrument "my_subscriber.unknown_event"
+ wait
+ # If we get here, it means that NoMethodError was raised.
+ end
+
+ def test_does_not_send_the_event_if_logger_is_nil
+ Rails.logger = nil
+ Rails::Subscriber.add :my_subscriber, @subscriber
+ instrument "my_subscriber.some_event"
+ wait
+ assert_equal [], @logger.logged(:info)
+ end
+end \ No newline at end of file