require 'active_support/core_ext/class/inheritable_attributes' require 'active_support/notifications' module Rails # Rails::LogSubscriber is an object set to consume ActiveSupport::Notifications # on initialization with solely purpose of logging. The log subscriber dispatches # notifications to a regirested object based on its given namespace. # # An example would be ActiveRecord log subscriber responsible for logging queries: # # module ActiveRecord # class Railtie # class LogSubscriber < Rails::LogSubscriber # def sql(event) # "#{event.payload[:name]} (#{event.duration}) #{event.payload[:sql]}" # end # end # end # end # # It's finally registed as: # # Rails::LogSubscriber.add :active_record, ActiveRecord::Railtie::LogSubscriber.new # # So whenever a "sql.active_record" notification arrive to Rails::LogSubscriber, # it will properly dispatch the event (ActiveSupport::Notifications::Event) to # the sql method. # # This is useful because it avoids spanning several log subscribers just for logging # purposes(which slows down the main thread). Besides of providing a centralized # facility on top of Rails.logger. # # Log subscriber also has some helpers to deal with logging and automatically flushes # all logs when the request finishes (via action_dispatch.callback notification). class LogSubscriber mattr_accessor :colorize_logging 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, log_subscriber, notifier = ActiveSupport::Notifications) log_subscribers << log_subscriber @flushable_loggers = nil log_subscriber.public_methods(false).each do |event| notifier.subscribe("#{event}.#{namespace}") do |*args| next if log_subscriber.logger.nil? begin log_subscriber.send(event, ActiveSupport::Notifications::Event.new(*args)) rescue Exception => e Rails.logger.error "Could not log #{args[0].inspect} event. #{e.class}: #{e.message}" end end end end def self.log_subscribers @log_subscribers ||= [] end def self.flushable_loggers @flushable_loggers ||= begin loggers = log_subscribers.map(&:logger) loggers.uniq! loggers.select { |l| l.respond_to?(:flush) } end end # Flush all log_subscribers' logger. def self.flush_all! flushable_loggers.each(&: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) return unless logger 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