Integrate Apache Commons JCI for Java Class Reloading

[sam]

Instead of using JRuby's built-in Ant support, as we do now, use Apache Commons JCI (which is already a dependency in the Jarfile) in conjunction with a file-watcher so that we can recompile on-the-fly and reload classes.

That would mean we don't have to restart our Java process for changes in the Java source.

[sam]

I don't think we're doing this after all. Unless perhaps we can get it to work by using the "eclipse" compiler shown in the usage examples?

I didn't try that previously since I assumed we needed the javac compiler, but since during searching the interwebs I ran across the -XX:-UseSplitVerifier issue mentioned in conjunction with Eclipse, it later occurred to me that the "eclipse" switch passed to the compiler factory might actually just be a set of alternative defaults for javac that avoid the issues we were having.

I'll experiment in irb real quick.

[sam]

Worked up the following script (after downloading the JCI JARs, and JCI-eclipse compiler):

#!/usr/bin/env jruby

require "pathname"
Pathname::glob("jars/jci/*.jar").each { |jar| require jar }

tmp = Pathname("tmp")
tmp.mkdir unless tmp.exist?

source = tmp + "java"
source.mkdir unless source.exist?

target = tmp + "target"
target.mkdir unless target.exist?

(source + "Cow.java").open("w+") do |cow|
  cow << <<-EOS
package org.sam.doubleshot;

public class Cow {
  public Cow() {}

  public String moo() {
    return "MOO!";
  }
}
EOS
end

compiler = org.apache.commons.jci.compilers.JavaCompilerFactory.new.create_compiler "eclipse"
result = compiler.compile(
  Pathname::glob(source + "**/*.java").map(&:to_s).to_java(:string),
  org.apache.commons.jci.readers.FileResourceReader.new(java.io.File.new(source.to_s)),
  org.apache.commons.jci.stores.FileResourceStore.new(java.io.File.new(target.to_s))
)

puts "#{result.errors.size} errors"
puts "#{result.warnings.size} warnings"

It still fails. On line 29 this time, so it can't even create_compiler "eclipse". Considering the code hasn't been updated in 5 years, I think this is just a dead-end.

Also, as far as I can tell, the ReloadingClassLoader doesn't do what I thought (reload classes on recompile), so we'd have to come up with another mechanism anyway.

Closing this ticket out. We'll need an alternative at some point.