require 'active_support/core_ext/module/attribute_accessors' require 'active_support/core_ext/class/attribute' module ActiveSupport # ActiveSupport::LogSubscriber is an object set to consume ActiveSupport::Notifications # with the sole purpose of logging them. The log subscriber dispatches notifications to # a registered object based on its given namespace. # # An example would be Active Record log subscriber responsible for logging queries: # # module ActiveRecord # class LogSubscriber < ActiveSupport::LogSubscriber # def sql(event) # "#{event.payload[:name]} (#{event.duration}) #{event.payload[:sql]}" # end # end # end # # And it's finally registered as: # # ActiveRecord::LogSubscriber.attach_to :active_record # # Since we need to know all instance methods before attaching the log subscriber, # the line above should be called after your ActiveRecord::LogSubscriber definition. # # After configured, whenever a "sql.active_record" notification is published, # it will properly dispatch the event (ActiveSupport::Notifications::Event) to # the sql method. # # Log subscriber also has some helpers to deal with logging and automatically flushes # all logs when the request finishes (via action_dispatch.callback notification) in # a Rails environment. class LogSubscriber # 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" mattr_accessor :colorize_logging self.colorize_logging = true class_attribute :logger class << self remove_method :logger def logger @logger ||= Rails.logger if defined?(Rails) end def attach_to(namespace, log_subscriber=new, notifier=ActiveSupport::Notifications) log_subscribers << log_subscriber @@flushable_loggers = nil log_subscriber.public_methods(false).each do |event| next if :call == event notifier.subscribe("#{event}.#{namespace}", log_subscriber) end end def log_subscribers @@log_subscribers ||= [] end def flushable_loggers @@flushable_loggers ||= begin loggers = log_subscribers.map(&:logger) loggers.uniq! loggers.select! { |l| l.respond_to?(:flush) } loggers end end # Flush all log_subscribers' logger. def flush_all! flushable_loggers.each { |log| log.flush } end end def call(message, *args) return unless logger method = message.split('.').first begin send(method, ActiveSupport::Notifications::Event.new(message, *args)) rescue Exception => e logger.error "Could not log #{message.inspect} event. #{e.class}: #{e.message} #{e.backtrace}" end end protected %w(info debug warn error fatal unknown).each do |level| class_eval <<-METHOD, __FILE__, __LINE__ + 1 def #{level}(progname = nil, &block) logger.#{level}(progname, &block) if logger 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 the Highline implementation and will automatically append 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.upcase) if color.is_a?(Symbol) bold = bold ? BOLD : "" "#{bold}#{color}#{text}#{CLEAR}" end end end