2013-04-21 11:39:48 -04:00
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require 'active_support/per_thread_registry'
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2013-04-15 09:23:46 -04:00
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module ActiveSupport
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# ActiveSupport::Subscriber is an object set to consume
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2013-04-16 10:50:50 -04:00
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# ActiveSupport::Notifications. The subscriber dispatches notifications to
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2013-04-15 09:23:46 -04:00
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# a registered object based on its given namespace.
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#
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2015-04-25 22:09:30 -04:00
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# An example would be an Active Record subscriber responsible for collecting
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2013-04-15 09:23:46 -04:00
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# statistics about queries:
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#
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# module ActiveRecord
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# class StatsSubscriber < ActiveSupport::Subscriber
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2015-03-24 11:10:15 -04:00
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# attach_to :active_record
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#
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# def sql(event)
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# Statsd.timing("sql.#{event.payload[:name]}", event.duration)
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# end
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# end
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# end
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#
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# After configured, whenever a "sql.active_record" notification is published,
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# it will properly dispatch the event (ActiveSupport::Notifications::Event) to
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2013-04-16 10:50:50 -04:00
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# the +sql+ method.
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2013-04-15 09:23:46 -04:00
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class Subscriber
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class << self
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# Attach the subscriber to a namespace.
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def attach_to(namespace, subscriber=new, notifier=ActiveSupport::Notifications)
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2013-09-19 05:03:58 -04:00
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@namespace = namespace
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@subscriber = subscriber
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@notifier = notifier
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2013-04-15 09:23:46 -04:00
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subscribers << subscriber
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2013-09-19 05:03:58 -04:00
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# Add event subscribers for all existing methods on the class.
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subscriber.public_methods(false).each do |event|
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add_event_subscriber(event)
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end
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end
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# Adds event subscribers for all new methods added to the class.
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def method_added(event)
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# Only public methods are added as subscribers, and only if a notifier
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# has been set up. This means that subscribers will only be set up for
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# classes that call #attach_to.
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if public_method_defined?(event) && notifier
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add_event_subscriber(event)
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2013-04-15 09:23:46 -04:00
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end
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end
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def subscribers
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@@subscribers ||= []
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end
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2013-09-19 05:03:58 -04:00
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protected
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attr_reader :subscriber, :notifier, :namespace
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def add_event_subscriber(event)
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return if %w{ start finish }.include?(event.to_s)
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2014-05-09 05:16:18 -04:00
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pattern = "#{event}.#{namespace}"
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2015-04-25 22:09:30 -04:00
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# Don't add multiple subscribers (eg. if methods are redefined).
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return if subscriber.patterns.include?(pattern)
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subscriber.patterns << pattern
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notifier.subscribe(pattern, subscriber)
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end
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2013-04-15 09:23:46 -04:00
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end
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2014-05-16 20:13:34 -04:00
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attr_reader :patterns # :nodoc:
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2013-04-15 09:23:46 -04:00
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def initialize
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@queue_key = [self.class.name, object_id].join "-"
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@patterns = []
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2013-04-15 09:23:46 -04:00
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super
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end
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def start(name, id, payload)
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e = ActiveSupport::Notifications::Event.new(name, Time.now, nil, id, payload)
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parent = event_stack.last
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parent << e if parent
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event_stack.push e
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end
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def finish(name, id, payload)
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finished = Time.now
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event = event_stack.pop
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event.end = finished
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event.payload.merge!(payload)
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Reduce object allocations in ActiveSupport::Subscriber
Freezing the string literal reduces the number of objects allocated
during integration test runs.
AllocationTracer before:
```
[["/rack/lib/rack/utils.rb", 499, :T_STRING], [50939, 2737, 78553, 0, 13, 1783920]]
[["/rails/activesupport/lib/active_support/subscriber.rb",
99, :T_STRING], [44959, 0, 42633, 0, 2, 1670800]]
[["/rack/lib/rack/utils.rb", 662, :T_STRING], [32979, 0, 31263, 0, 1, 1226009]]
[["/rack/lib/rack/body_proxy.rb", 34, :T_ARRAY], [29988, 0, 28438, 0, 1, 1114320]]
[["/rails/activesupport/lib/active_support/callbacks.rb", 165, :T_DATA], [29968, 0, 28422, 0, 2, 3675936]]
```
AllocationTracer after:
```
[["/rack/lib/rack/utils.rb", 499, :T_STRING], [50983, 4080, 67269, 0, 12, 1815600]]
[["/rack/lib/rack/utils.rb", 662, :T_STRING], [33001, 0, 28420, 0, 2, 1230809]]
[["/rack/lib/rack/body_proxy.rb", 34, :T_ARRAY], [29990, 0, 25812, 0, 1, 1118000]]
[["/rails/activesupport/lib/active_support/subscriber.rb", 99, :T_STRING], [29986, 0, 25803, 0, 1, 1117840]]
[["/rails/activesupport/lib/active_support/notifications/instrumenter.rb", 52, :T_HASH], [29984, 28, 26133, 0, 11, 4953280]]
2015-02-11 11:01:13 -05:00
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method = name.split('.'.freeze).first
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2013-04-15 09:23:46 -04:00
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send(method, event)
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end
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private
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2013-04-21 11:39:48 -04:00
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def event_stack
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2013-11-06 19:32:47 -05:00
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SubscriberQueueRegistry.instance.get_queue(@queue_key)
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2013-04-21 11:39:48 -04:00
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end
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end
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# This is a registry for all the event stacks kept for subscribers.
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#
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# See the documentation of <tt>ActiveSupport::PerThreadRegistry</tt>
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# for further details.
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class SubscriberQueueRegistry # :nodoc:
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extend PerThreadRegistry
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def initialize
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@registry = {}
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end
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def get_queue(queue_key)
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@registry[queue_key] ||= []
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2013-04-15 09:23:46 -04:00
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end
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end
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end
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