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# frozen_string_literal: true
require "mutex_m"
require "concurrent/map"
require "set"
module ActiveSupport
module Notifications
# 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.
class Fanout
include Mutex_m
def initialize
@string_subscribers = Hash.new { |h, k| h[k] = [] }
@other_subscribers = []
@listeners_for = Concurrent::Map.new
super
end
def subscribe(pattern = nil, callable = nil, &block)
subscriber = Subscribers.new(pattern, callable || block)
synchronize do
if String === pattern
@string_subscribers[pattern] << subscriber
@listeners_for.delete(pattern)
else
@other_subscribers << subscriber
@listeners_for.clear
end
end
subscriber
end
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
def start(name, id, payload)
listeners_for(name).each { |s| s.start(name, id, payload) }
end
def finish(name, id, payload, listeners = listeners_for(name))
listeners.each { |s| s.finish(name, id, payload) }
end
def publish(name, *args)
listeners_for(name).each { |s| s.publish(name, *args) }
end
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
def listening?(name)
listeners_for(name).any?
end
# This is a sync queue, so there is no waiting.
def wait
end
module Subscribers # :nodoc:
def self.new(pattern, listener)
subscriber_class = Timed
if listener.respond_to?(:start) && listener.respond_to?(:finish)
subscriber_class = Evented
else
# Doing all this to detect a block like `proc { |x| }` vs
# `proc { |*x| }` or `proc { |**x| }`
if listener.respond_to?(:parameters)
params = listener.parameters
if params.length == 1 && params.first.first == :opt
subscriber_class = EventObject
end
end
end
wrap_all pattern, subscriber_class.new(pattern, listener)
end
def self.event_object_subscriber(pattern, block)
wrap_all pattern, EventObject.new(pattern, block)
end
def self.wrap_all(pattern, subscriber)
unless pattern
AllMessages.new(subscriber)
else
subscriber
end
end
class Matcher #:nodoc:
attr_reader :pattern, :exclusions
def self.wrap(pattern)
return pattern if String === pattern
new(pattern)
end
def initialize(pattern)
@pattern = pattern
@exclusions = Set.new
end
def unsubscribe!(name)
exclusions << -name if pattern === name
end
def ===(name)
pattern === name && !exclusions.include?(name)
end
end
class Evented #:nodoc:
attr_reader :pattern
def initialize(pattern, delegate)
@pattern = Matcher.wrap(pattern)
@delegate = delegate
@can_publish = delegate.respond_to?(:publish)
end
def publish(name, *args)
if @can_publish
@delegate.publish name, *args
end
end
def start(name, id, payload)
@delegate.start name, id, payload
end
def finish(name, id, payload)
@delegate.finish name, id, payload
end
def subscribed_to?(name)
pattern === name
end
def matches?(name)
pattern && pattern === name
end
def unsubscribe!(name)
pattern.unsubscribe!(name)
end
end
class Timed < Evented # :nodoc:
def publish(name, *args)
@delegate.call name, *args
end
def start(name, id, payload)
timestack = Thread.current[:_timestack] ||= []
timestack.push Time.now
end
def finish(name, id, payload)
timestack = Thread.current[:_timestack]
started = timestack.pop
@delegate.call(name, started, Time.now, id, payload)
end
end
class EventObject < Evented
def start(name, id, payload)
stack = Thread.current[:_event_stack] ||= []
event = build_event name, id, payload
event.start!
stack.push event
end
def finish(name, id, payload)
stack = Thread.current[:_event_stack]
event = stack.pop
event.finish!
@delegate.call event
end
private
def build_event(name, id, payload)
ActiveSupport::Notifications::Event.new name, nil, nil, id, payload
end
end
class AllMessages # :nodoc:
def initialize(delegate)
@delegate = delegate
end
def start(name, id, payload)
@delegate.start name, id, payload
end
def finish(name, id, payload)
@delegate.finish name, id, payload
end
def publish(name, *args)
@delegate.publish name, *args
end
def subscribed_to?(name)
true
end
def unsubscribe!(*)
false
end
alias :matches? :===
end
end
end
end
end
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