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rails--rails/activesupport/lib/active_support/descendants_tracker.rb
Jonathan Hefner 8f8aa857e0 Alias direct_descendants as subclasses
This alias overrides Class#subclasses.  Thus calls to `subclasses` get a
free performance boost when the class extends DescendantsTracker.
2020-06-02 22:57:48 -05:00

112 lines
2.6 KiB
Ruby

# frozen_string_literal: true
require "weakref"
module ActiveSupport
# This module provides an internal implementation to track descendants
# which is faster than iterating through ObjectSpace.
module DescendantsTracker
@@direct_descendants = {}
class << self
def direct_descendants(klass)
descendants = @@direct_descendants[klass]
descendants ? descendants.to_a : []
end
alias_method :subclasses, :direct_descendants
def descendants(klass)
arr = []
accumulate_descendants(klass, arr)
arr
end
def clear
if defined? ActiveSupport::Dependencies
@@direct_descendants.each do |klass, descendants|
if Dependencies.autoloaded?(klass)
@@direct_descendants.delete(klass)
else
descendants.reject! { |v| Dependencies.autoloaded?(v) }
end
end
else
@@direct_descendants.clear
end
end
# This is the only method that is not thread safe, but is only ever called
# during the eager loading phase.
def store_inherited(klass, descendant)
(@@direct_descendants[klass] ||= DescendantsArray.new) << descendant
end
private
def accumulate_descendants(klass, acc)
if direct_descendants = @@direct_descendants[klass]
direct_descendants.each do |direct_descendant|
acc << direct_descendant
accumulate_descendants(direct_descendant, acc)
end
end
end
end
def inherited(base)
DescendantsTracker.store_inherited(self, base)
super
end
def direct_descendants
DescendantsTracker.direct_descendants(self)
end
alias_method :subclasses, :direct_descendants
def descendants
DescendantsTracker.descendants(self)
end
# DescendantsArray is an array that contains weak references to classes.
class DescendantsArray # :nodoc:
include Enumerable
def initialize
@refs = []
end
def initialize_copy(orig)
@refs = @refs.dup
end
def <<(klass)
@refs << WeakRef.new(klass)
end
def each
@refs.reject! do |ref|
yield ref.__getobj__
false
rescue WeakRef::RefError
true
end
self
end
def refs_size
@refs.size
end
def cleanup!
@refs.delete_if { |ref| !ref.weakref_alive? }
end
def reject!
@refs.reject! do |ref|
yield ref.__getobj__
rescue WeakRef::RefError
true
end
end
end
end
end