Class: ActiveSupport::Subscriber
- Defined in:
- lib/active_support/subscriber.rb
Overview
Active Support Subscriber
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.
We can detach a subscriber as well:
ActiveRecord::StatsSubscriber.detach_from(:active_record)
Direct Known Subclasses
Instance Attribute Summary collapse
-
#patterns ⇒ Object
readonly
:nodoc:.
Class Method Summary collapse
-
.attach_to(namespace, subscriber = new, notifier = ActiveSupport::Notifications, inherit_all: false) ⇒ Object
Attach the subscriber to a namespace.
-
.detach_from(namespace, notifier = ActiveSupport::Notifications) ⇒ Object
Detach the subscriber from a namespace.
-
.method_added(event) ⇒ Object
Adds event subscribers for all new methods added to the class.
- .subscribers ⇒ Object
Instance Method Summary collapse
- #call(event) ⇒ Object
-
#initialize ⇒ Subscriber
constructor
A new instance of Subscriber.
-
#publish_event(event) ⇒ Object
:nodoc:.
Constructor Details
#initialize ⇒ Subscriber
Returns a new instance of Subscriber.
130 131 132 133 |
# File 'lib/active_support/subscriber.rb', line 130 def initialize @patterns = {} super end |
Instance Attribute Details
#patterns ⇒ Object (readonly)
:nodoc:
128 129 130 |
# File 'lib/active_support/subscriber.rb', line 128 def patterns @patterns end |
Class Method Details
.attach_to(namespace, subscriber = new, notifier = ActiveSupport::Notifications, inherit_all: false) ⇒ Object
Attach the subscriber to a namespace.
35 36 37 38 39 40 41 42 43 44 45 46 47 |
# File 'lib/active_support/subscriber.rb', line 35 def attach_to(namespace, subscriber = new, notifier = ActiveSupport::Notifications, inherit_all: false) @namespace = namespace @subscriber = subscriber @notifier = notifier @inherit_all = inherit_all subscribers << subscriber # Add event subscribers for all existing methods on the class. fetch_public_methods(subscriber, inherit_all).each do |event| add_event_subscriber(event) end end |
.detach_from(namespace, notifier = ActiveSupport::Notifications) ⇒ Object
Detach the subscriber from a namespace.
50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 |
# File 'lib/active_support/subscriber.rb', line 50 def detach_from(namespace, notifier = ActiveSupport::Notifications) @namespace = namespace @subscriber = find_attached_subscriber @notifier = notifier return unless subscriber subscribers.delete(subscriber) # Remove event subscribers of all existing methods on the class. fetch_public_methods(subscriber, true).each do |event| remove_event_subscriber(event) end # Reset notifier so that event subscribers will not add for new methods added to the class. @notifier = nil end |
.method_added(event) ⇒ Object
Adds event subscribers for all new methods added to the class.
69 70 71 72 73 74 75 76 |
# File 'lib/active_support/subscriber.rb', line 69 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 |
.subscribers ⇒ Object
78 79 80 |
# File 'lib/active_support/subscriber.rb', line 78 def subscribers @@subscribers ||= [] end |
Instance Method Details
#call(event) ⇒ Object
135 136 137 138 |
# File 'lib/active_support/subscriber.rb', line 135 def call(event) method = event.name[0, event.name.index(".")] send(method, event) end |
#publish_event(event) ⇒ Object
:nodoc:
140 141 142 143 |
# File 'lib/active_support/subscriber.rb', line 140 def publish_event(event) # :nodoc: method = event.name[0, event.name.index(".")] send(method, event) end |