class ActiveSupport::LogSubscriber
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.
Constants
- BLACK
Colors
- BLUE
- BOLD
- CLEAR
Embed in a String to clear all previous ANSI sequences.
- CYAN
- GREEN
- MAGENTA
- RED
- WHITE
- YELLOW
Attributes
Public Class Methods
Flush all ::log_subscribers' logger.
# File lib/active_support/log_subscriber.rb, line 69 def flush_all! logger.flush if logger.respond_to?(:flush) end
# File lib/active_support/log_subscriber.rb, line 64 def log_subscribers subscribers end
# File lib/active_support/log_subscriber.rb, line 56 def logger @logger ||= if defined?(Rails) && Rails.respond_to?(:logger) Rails.logger end end
Public Instance Methods
# File lib/active_support/log_subscriber.rb, line 82 def finish(name, id, payload) super if logger rescue Exception => e logger.error "Could not log #{name.inspect} event. #{e.class}: #{e.message} #{e.backtrace}" end
# File lib/active_support/log_subscriber.rb, line 74 def logger LogSubscriber.logger end
# File lib/active_support/log_subscriber.rb, line 78 def start(name, id, payload) super if logger end
Protected Instance Methods
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.
# File lib/active_support/log_subscriber.rb, line 102 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