aboutsummaryrefslogtreecommitdiffstats
path: root/activesupport/lib/active_support/log_subscriber.rb
blob: c4b64bd1a602b42a7bba1bcd53c43934f174287a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
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
  # <tt>ActiveRecord::LogSubscriber</tt> 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 << self
      def logger
        @logger ||= if defined?(Rails) && Rails.respond_to?(:logger)
          Rails.logger
        end
      end

      attr_writer :logger

      def attach_to(namespace, log_subscriber=new, notifier=ActiveSupport::Notifications)
        log_subscribers << log_subscriber

        log_subscriber.public_methods(false).each do |event|
          next if %w{ start finish }.include?(event.to_s)

          notifier.subscribe("#{event}.#{namespace}", log_subscriber)
        end
      end

      def log_subscribers
        @@log_subscribers ||= []
      end

      # Flush all log_subscribers' logger.
      def flush_all!
        logger.flush if logger.respond_to?(:flush)
      end
    end

    def initialize
      @queue_key = [self.class.name, object_id].join  "-"
      super
    end

    def logger
      LogSubscriber.logger
    end

    def start(name, id, payload)
      return unless logger

      e = ActiveSupport::Notifications::Event.new(name, Time.now, nil, id, payload)
      parent = event_stack.last
      parent << e if parent

      event_stack.push e
    end

    def finish(name, id, payload)
      return unless logger

      finished  = Time.now
      event     = event_stack.pop
      event.end = finished
      event.payload.merge!(payload)

      method = name.split('.').first
      begin
        send(method, event)
      rescue Exception => e
        logger.error "Could not log #{name.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

    private

    def event_stack
      Thread.current[@queue_key] ||= []
    end
  end
end