Class: ActiveSupport::Notifications::Fanout

Inherits:
Object
  • Object
show all
Includes:
Mutex_m
Defined in:
lib/active_support/notifications/fanout.rb

Overview

This is a default queue implementation that ships with Notifications. It just pushes events to all registered log subscribers.

This class is thread safe. All methods are reentrant.

Defined Under Namespace

Modules: Subscribers

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Fanout

Returns a new instance of Fanout.



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# File 'lib/active_support/notifications/fanout.rb', line 27

def initialize
  @string_subscribers = Hash.new { |h, k| h[k] = [] }
  @other_subscribers = []
  @listeners_for = Concurrent::Map.new
  super
end

Instance Method Details

#finish(name, id, payload, listeners = listeners_for(name)) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 75

def finish(name, id, payload, listeners = listeners_for(name))
  iterate_guarding_exceptions(listeners) { |s| s.finish(name, id, payload) }
end

#iterate_guarding_exceptions(listeners) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 87

def iterate_guarding_exceptions(listeners)
  exceptions = nil

  listeners.each do |s|
    yield s
  rescue Exception => e
    exceptions ||= []
    exceptions << e
  end

  if exceptions
    if exceptions.size == 1
      raise exceptions.first
    else
      raise InstrumentationSubscriberError.new(exceptions), cause: exceptions.first
    end
  end

  listeners
end

#listeners_for(name) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 108

def listeners_for(name)
  # this is correctly done double-checked locking (Concurrent::Map's lookups have volatile semantics)
  @listeners_for[name] || synchronize do
    # use synchronisation when accessing @subscribers
    @listeners_for[name] ||=
      @string_subscribers[name] + @other_subscribers.select { |s| s.subscribed_to?(name) }
  end
end

#listening?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_support/notifications/fanout.rb', line 117

def listening?(name)
  listeners_for(name).any?
end

#publish(name, *args) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 79

def publish(name, *args)
  iterate_guarding_exceptions(listeners_for(name)) { |s| s.publish(name, *args) }
end

#publish_event(event) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 83

def publish_event(event)
  iterate_guarding_exceptions(listeners_for(event.name)) { |s| s.publish_event(event) }
end

#start(name, id, payload) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 71

def start(name, id, payload)
  iterate_guarding_exceptions(listeners_for(name)) { |s| s.start(name, id, payload) }
end

#subscribe(pattern = nil, callable = nil, monotonic: false, &block) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 34

def subscribe(pattern = nil, callable = nil, monotonic: false, &block)
  subscriber = Subscribers.new(pattern, callable || block, monotonic)
  synchronize do
    case pattern
    when String
      @string_subscribers[pattern] << subscriber
      @listeners_for.delete(pattern)
    when NilClass, Regexp
      @other_subscribers << subscriber
      @listeners_for.clear
    else
      raise ArgumentError,  "pattern must be specified as a String, Regexp or empty"
    end
  end
  subscriber
end

#unsubscribe(subscriber_or_name) ⇒ Object 



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# File 'lib/active_support/notifications/fanout.rb', line 51

def unsubscribe(subscriber_or_name)
  synchronize do
    case subscriber_or_name
    when String
      @string_subscribers[subscriber_or_name].clear
      @listeners_for.delete(subscriber_or_name)
      @other_subscribers.each { |sub| sub.unsubscribe!(subscriber_or_name) }
    else
      pattern = subscriber_or_name.try(:pattern)
      if String === pattern
        @string_subscribers[pattern].delete(subscriber_or_name)
        @listeners_for.delete(pattern)
      else
        @other_subscribers.delete(subscriber_or_name)
        @listeners_for.clear
      end
    end
  end
end

#wait ⇒ Object

This is a sync queue, so there is no waiting.



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# File 'lib/active_support/notifications/fanout.rb', line 122

def wait
end