Class: NewRelic::Agent::EventListener

Inherits:

Object

• Object
• NewRelic::Agent::EventListener

Defined in:

lib/new_relic/agent/event_listener.rb

Overview

Basic mechanism for the agent instance to provide agent-wide eventing. It is intended to keep different pieces of the app decoupled from each other.

While an EventListener could be used elsewhere, it’s strongly expected your eventing needs should be met by the agent’s instance.

Instance Attribute Summary

• #runaway_threshold ⇒ Object

  Returns the value of attribute runaway_threshold.

Instance Method Summary

• #check_for_runaway_subscriptions(event) ⇒ Object
• #clear ⇒ Object
• #initialize ⇒ EventListener constructor

  A new instance of EventListener.

• #notify(event, *args) ⇒ Object
• #subscribe(event, &handler) ⇒ Object

Constructor Details

#initialize ⇒ EventListener

Returns a new instance of EventListener.

# File 'lib/new_relic/agent/event_listener.rb', line 14

def initialize
  @events = {}
  @runaway_threshold = 100
end

Instance Attribute Details

#runaway_threshold ⇒ Object

Returns the value of attribute runaway_threshold.

# File 'lib/new_relic/agent/event_listener.rb', line 12

def runaway_threshold
  @runaway_threshold
end

Instance Method Details

#check_for_runaway_subscriptions(event) ⇒ Object

# File 'lib/new_relic/agent/event_listener.rb', line 25

def check_for_runaway_subscriptions(event)
  count = @events[event].size
  NewRelic::Agent.logger.debug("Run-away event subscription on #{event}? Subscribed #{count}") if count > @runaway_threshold
end

#clear ⇒ Object

# File 'lib/new_relic/agent/event_listener.rb', line 30

def clear
  @events.clear
end

#notify(event, *args) ⇒ Object

# File 'lib/new_relic/agent/event_listener.rb', line 34

def notify(event, *args)
  return unless @events.has_key?(event)

  @events[event].each do |handler|
    begin
      handler.call(*args)
    rescue => err
      NewRelic::Agent.logger.debug("Failure during notify for #{event}", err)
    end
  end
end

#subscribe(event, &handler) ⇒ Object

# File 'lib/new_relic/agent/event_listener.rb', line 19

def subscribe(event, &handler)
  @events[event] ||= []
  @events[event] << handler
  check_for_runaway_subscriptions(event)
end