Can't load class files in WARs compiled by warbler using jruby 1.7.0.preview1

Adding boot.rb file requiring boot.class to the attachments.

UPDATE: The app will load properly if I change all of the .rb files from

require __FILE__.sub(/.rb$/, '.class')

to

load __FILE__.sub(/.rb$/, '.class')

Scott: I think your fix might actually be a great one, since it avoids polluting "loaded features" with .class entries and treats the .class files as "hidden source" for the .rb files. But you should refile this on the jruby-rack tracker, under the github project (https://github.com/jruby/jruby-rack I think).

Double post

Well, I filed a bug with jruby-rack, and they're sending me back to you. In all honesty, it does really seem like a JRuby issue, as the problem only presents itself in JRuby 1.7. But if the suggested workaround is to change all of the requires to loads, then perhaps, it should be filed as a Warbler bug after all, since it is Warbler that is generating these files.
https://github.com/jruby/jruby-rack/issues/111#issuecomment-6691702

Ok, investigating today. A quick test fails in an unexpected way (for me):

system ~/projects/jruby $ ls load*
loadable.class	loadable.rb	loader.rb

system ~/projects/jruby $ cat loader.rb
require 'loadable.class'

system ~/projects/jruby $ cat loadable.rb 
puts 'here'

system ~/projects/jruby $ jruby --1.8 loader.rb 
LoadError: no such file to load -- loadable.class
  require at org/jruby/RubyKernel.java:1004
   (root) at loader.rb:1

system ~/projects/jruby $ rvm jruby do ruby --1.9 -v loader.rb
jruby 1.6.7.2 (ruby-1.9.2-p312) (2012-05-01 26e08ba) (Java HotSpot(TM) 64-Bit Server VM 1.7.0_04) [darwin-x86_64-java]
LoadError: no such file to load -- loadable.class
  require at org/jruby/RubyKernel.java:1042
  require at /Users/headius/.rvm/rubies/jruby-1.6.7.2/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:36
   (root) at loader.rb:1

However, as you can see it fails in 1.6.7.2 as well. Hmmm.

Well I'm confused about why this would have started failing in 1.7. There are no related changes I can see in the relevant code in JRuby (LoadService.java) during the post 1.6.7 dev cycle. I also don't see how it would have ever worked before.

The logic currently works like this:

• If require name has no extension, search for both source and ext (.rb, .class, and .dll/.so/.bundle).
• If require name has a .rb extension, search for source forms (.rb and .class).
• If require name has a .class extension, search for both source and ext using original name as base (e.g. require 'foo.class' will try 'foo.class.rb' and 'foo.class.class').

This last bullet does not appear to have changed in a long time, and is the primary reason why this fails.

There are a couple possible fixes:

• Treat a require of a .class file as an exact filename; do not search for anything other than that filename.
• Treat a require of a .class file as a source search; try .class and .rb in that order.

I'm inclined to do the former, since I believe that most accurately reflects the intent. The .rb => .class search in the bullets above was intended to allow scripts that require .rb files to work unmodified when precompiling. I don't see a use case where you'd want an explicit require of precompiled code to load .rb files.

HOWEVER...all that said, I still think warbler should be using load instead of require. Using require adds .class entries to "loaded features" which is a visible change, where precompilation is intended to be an invisible feature. I also see no harm in using load; what we want here is basically to take the guts out of a .rb file, stuff them in a .class file, and pretend nothing has changed. That's load, not require.

I will try to raise this with the warbler folks again.

Ok, I said my piece on the Warbler issue.

I think @kares may have misunderstood what we were asking for, since he mentioned changing a require of boot.rb into a load of boot.rb. Hopefully my explanation will clear things up.

I will proceed with the require fix.

Fixed as described. Note that this should allow Warbler's current mechanism to function, but I still believe it should use load instead of require.

commit 7c4238ab08c1df6f238e7b0b79d1bc7f07ebf1d6
Author: Charles Oliver Nutter <headius@headius.com>
Date:   Thu Jul 26 17:16:43 2012 -0500

    Fix JRUBY-6731
    
    Can't load class files in WARs compiled by warbler using jruby 1.7.0.preview1
    
    When requiring a file with an explicit .class extension, assume
    the .class filename is the only filename to be searched.
    
    Because a require of .class almost always will indicate that the
    user wants to load a specific precompiled Ruby file, there's no
    good reason (I know of) to search for anything else.
    
    The original logic did not work at all; require 'foo.class' would
    search for 'foo.class.rb' and 'foo.class.class' (in that order)
    but never 'foo.class'.
    
    The claim is that this worked in 1.6.7.2, but I could not
    reproduce that with a simple case. The logic involved does not
    appear to have changed in a substantial way since well before
    1.6.7.2, and in any case I believe the fix here is the right way
    for it to work.

:100644 100644 bb7a9d6... 3c38f56... M	src/org/jruby/runtime/load/LoadService.java

BTW JRUBY-6348 is probably the same bug (and probably can be closed too).

I've been using a work-around in production since February (if anybody needs one):

# place this hack in top of config/warbler.rb
# HACK https://github.com/jruby/warbler/issues/55 (require vs. load)
class Warbler::Jar
  def replace_compiled_ruby_files(config, compiled_ruby_files)
    config.excludes += compiled_ruby_files
    compiled_ruby_files.each do |ruby_source|
      files[apply_pathmaps(config, ruby_source, :application)] = StringIO.new("load __FILE__.sub(/\.rb$/, '.class')")
    end
  end
end

Thanks! I've also created a ticket for the Warbler devs here:
https://github.com/jruby/warbler/issues/102