/
subscriber.rb
130 lines (105 loc) · 3.54 KB
/
subscriber.rb
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
# frozen_string_literal: true
require "active_support/per_thread_registry"
require "active_support/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, now, nil, id, payload)
parent = event_stack.last
parent << e if parent
event_stack.push e
end
def finish(name, id, payload)
finished = 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
def now
Process.clock_gettime(Process::CLOCK_MONOTONIC)
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