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
|
# frozen_string_literal: true
require_relative "per_thread_registry"
require_relative "notifications"
module ActiveSupport
# ActiveSupport::Subscriber is an object set to consume
# ActiveSupport::Notifications. The subscriber dispatches notifications to
# a registered object based on its given namespace.
#
# An example would be an Active Record subscriber responsible for collecting
# statistics about queries:
#
# module ActiveRecord
# class StatsSubscriber < ActiveSupport::Subscriber
# attach_to :active_record
#
# def sql(event)
# Statsd.timing("sql.#{event.payload[:name]}", event.duration)
# end
# end
# end
#
# After configured, whenever a "sql.active_record" notification is published,
# it will properly dispatch the event (ActiveSupport::Notifications::Event) to
# the +sql+ method.
class Subscriber
class << self
# Attach the subscriber to a namespace.
def attach_to(namespace, subscriber = new, notifier = ActiveSupport::Notifications)
@namespace = namespace
@subscriber = subscriber
@notifier = notifier
subscribers << subscriber
# Add event subscribers for all existing methods on the class.
subscriber.public_methods(false).each do |event|
add_event_subscriber(event)
end
end
# Adds event subscribers for all new methods added to the class.
def method_added(event)
# Only public methods are added as subscribers, and only if a notifier
# has been set up. This means that subscribers will only be set up for
# classes that call #attach_to.
if public_method_defined?(event) && notifier
add_event_subscriber(event)
end
end
def subscribers
@@subscribers ||= []
end
# TODO Change this to private once we've dropped Ruby 2.2 support.
# Workaround for Ruby 2.2 "private attribute?" warning.
protected
attr_reader :subscriber, :notifier, :namespace
private
def add_event_subscriber(event) # :doc:
return if %w{ start finish }.include?(event.to_s)
pattern = "#{event}.#{namespace}"
# Don't add multiple subscribers (eg. if methods are redefined).
return if subscriber.patterns.include?(pattern)
subscriber.patterns << pattern
notifier.subscribe(pattern, subscriber)
end
end
attr_reader :patterns # :nodoc:
def initialize
@queue_key = [self.class.name, object_id].join "-"
@patterns = []
super
end
def start(name, id, payload)
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)
finished = Time.now
event = event_stack.pop
event.end = finished
event.payload.merge!(payload)
method = name.split(".".freeze).first
send(method, event)
end
private
def event_stack
SubscriberQueueRegistry.instance.get_queue(@queue_key)
end
end
# This is a registry for all the event stacks kept for subscribers.
#
# See the documentation of <tt>ActiveSupport::PerThreadRegistry</tt>
# for further details.
class SubscriberQueueRegistry # :nodoc:
extend PerThreadRegistry
def initialize
@registry = {}
end
def get_queue(queue_key)
@registry[queue_key] ||= []
end
end
end
|
