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require "chef/event_dispatch/base"
class Chef
module EventDispatch
# == EventDispatch::Dispatcher
# The Dispatcher handles receiving event data from the sources
# (Chef::Client, Resources and Providers, etc.) and publishing the data to
# the registered subscribers.
class Dispatcher < Base
attr_reader :subscribers
attr_reader :event_list
def initialize(*subscribers)
@subscribers = subscribers
@event_list = []
end
# Add a new subscriber to the list of registered subscribers
def register(subscriber)
subscribers << subscriber
end
def unregister(subscriber)
subscribers.reject! { |x| x == subscriber }
end
def enqueue(method_name, *args)
event_list << [ method_name, *args ]
process_events_until_done unless @in_call
end
(Base.instance_methods - Object.instance_methods).each do |method_name|
class_eval <<-EOM
def #{method_name}(*args)
enqueue(#{method_name.inspect}, *args)
end
EOM
end
# Special case deprecation, since it needs to know its caller
def deprecation(message, location = caller(2..2)[0])
enqueue(:deprecation, message, location)
end
# Check to see if we are dispatching to a formatter
# @api private
def formatter?
subscribers.any? { |s| s.respond_to?(:is_formatter?) && s.is_formatter? }
end
####
# All messages are unconditionally forwarded to all subscribers, so just
# define the forwarding in one go:
#
# @api private
def call_subscribers(method_name, *args)
@in_call = true
subscribers.each do |s|
# Skip new/unsupported event names
next if !s.respond_to?(method_name)
mth = s.method(method_name)
# Trim arguments to match what the subscriber expects to allow
# adding new arguments without breaking compat.
if mth.arity < args.size && mth.arity >= 0
mth.call(*args.take(mth.arity))
else
mth.call(*args)
end
end
ensure
@in_call = false
end
private
# events are allowed to enqueue chained events, so pop them off until
# empty, rather than iterating over the list.
#
def process_events_until_done
call_subscribers(*event_list.shift) until event_list.empty?
end
end
end
end
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