[ANN] weakling 0.0.1 - a reference queue and weak ID hash for JRuby

Hi all!

JRuby 1.5 will soon be released, in which ObjectSpace._id2ref does not
function unless ObjectSpace is turned on. Since the typical pattern
for _id2ref is to have a weak-valued hash of numeric IDs to objects,
I’ve released a simple extension to JRuby that provides a weak
id-to-object hash implementation plus support for weak reference
queues. Comments, questions, suggestions are welcome.

Announcing the “weakling” library!

weakling: a collection of weakref utilities for Ruby (JRuby only for the

== Summary ==

This library provides:

  • a modified WeakRef implementation for JRuby that supports a reference
  • a WeakRef::RefQueue class
  • a weak-valued ID map to replace typical uses of _id2ref

In the future it may provide additional features like a generic
WeakHash or other reference types like soft and phantom references.

The weakling repository is at GitHub - headius/weakling: A modified WeakRef impl for JRuby plus some weakref-related tools.

== Usage ==

Just require ‘weakling’. It will require ‘weakref’ along with the
refqueue JRuby extension and the weakling/collections library
containing the weak id hash.

== RefQueue Example ==

require ‘weakling’
require ‘java’

q = WeakRef::RefQueue.new
wr = WeakRef.new(Object.new, q)
puts “weakref object: #{wr.id}”

puts “running GC”

puts “weakref alive?: #{wr.weakref_alive?}”
puts “weakref object from queue: #{q.poll.id}”

== WeakRef::IdHash Example ==

require ‘weakling’

wh = WeakRef::IdHash.new

ary = (1…10).to_a.map {Object.new}
ids = ary.map {|o| wh.add(o)}

puts “all items in weak_id_hash:”
ids.each {|i| puts “#{i} = #{wh[i]}”}

puts “dereferencing objects”
ary = nil

puts “forcing GC”
require ‘java’

puts “all items in weak id hash:”
ids.each {|i| puts “#{i} = #{wh[i]}”}

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