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