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. # # Subscriber also has some helpers to deal with logging and automatically flushes # all logs when the request finishes (via action_dispatch.callback notification). class Subscriber mattr_accessor :colorize_logging, :log_tailer 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 begin subscriber.send(name, ActiveSupport::Notifications::Event.new(*args)) rescue Exception => e Rails.logger.error "Could not log #{args[0].inspect} event. #{e.class}: #{e.message}" end end if args[0] == "action_dispatch.after_dispatch" && !subscribers.empty? flush_all! log_tailer.tail! if log_tailer end end # Flush all subscribers' logger. def self.flush_all! loggers = subscribers.values.map(&:logger) loggers.uniq! loggers.each { |l| l.flush if l.respond_to?(:flush) } 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