ObjectSpace is disabled by default in JRuby

[utgarda]

... so, though spec runs cool with normal Ruby, this call @space.point_query_first(point, CP::ALL_ONES, 0) with JRuby drops a warning and return just nil. chipmunk-ffi-1.0.0/lib/chipmunk-ffi/space.rb:290 warning: ObjectSpace is disabled; _id2ref only supports immediates, pass -X+O to enable

Yep, guess I can enable it back, even dynamically, so this is not so big an issue, require 'jruby' JRuby.objectspace=true but before disabling ObjectSpace by default, they discussed if they should do it in the first place : http://www.ruby-forum.com/topic/129606 and they say it gains up to 10 times better performance.

ObjectSpace._id2ref is used in chipmunk-ffi quite a lot ( 11 times ), so, I guess, it's essential for the library?

[shawn42]

The original C extension could just pass ruby object pointers into the chipmunk callbacks, and viola you had a ruby object. We could possibly keep our own global count and hash to use, that may help with performance, not sure about GC problems though. I'm open to suggestions.

[philomory]

We could avoid holding onto objects that would otherwise be garbage collected by using WeakRefs in our hash. So, every time a shape, body, constraint, etc is created, store the object_id in the data field as we do now (doesn't have to be obj_id, but, that guarantees uniqueness and is readily available), then, insert a pair into our hash, with the object_id (or whatever we put in the data field) as the key, and as the value, WeakRef.new(<the object we just created>). I wonder what the performance of that would be, in comparison?

[utgarda]

For the time being, I just enabled ObjectSpace dynamically : utgarda@7b7de31f536a804bc1e2c01fd5a04ac13ceb6f68 to try to get specs working.

[shawn42]

.