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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 solely purpose of logging. The log subscriber dispatches notifications to a
# regirested 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 registed 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
mattr_accessor :colorize_logging
self.colorize_logging = true
class_attribute :logger
class << self
remove_method :logger
end
def self.logger
@logger ||= Rails.logger if defined?(Rails)
end
# 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.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.to_s
notifier.subscribe("#{event}.#{namespace}", log_subscriber)
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
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}"
end
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
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