JRuby hacking guide

My talk about JRuby internals at Euruko 2011.

Transcript

1. JRuby hacking guide David Calavera @calavera
2. +70 contributors
3. 9 core members
4. 30 single commits ~
5. we want you
6. core
7. rule of thumb
8. jruby-1.6.2 :003 > raise ArgumentError.new ArgumentError: ArgumentError from (irb):3:in `evaluate' from org/jruby/RubyKernel.java:1088:in `e from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:158:in `eval_input' from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:271:in `signal_status' from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:155:in `eval_input' from org/jruby/RubyKernel.java:1419:in `l from org/jruby/RubyKernel.java:1191:in `c from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:154:in `eval_input' from /Users/david/.rvm/rubies/jruby-1.6.2
9. do not freak out
10. ruby-1.8.7 :001 > raise ArgumentError.new ArgumentError: ArgumentError from (irb):1
11. jruby-1.6.2 :001 > raise ArgumentError.new ArgumentError: ArgumentError from (irb):1:in `evaluate' from org/jruby/RubyKernel.java:1088:in `e from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:158:in `eval_input' from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:271:in `signal_status' from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:155:in `eval_input' from org/jruby/RubyKernel.java:1419:in `l from org/jruby/RubyKernel.java:1191:in `c from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:154:in `eval_input' from /Users/david/.rvm/rubies/jruby-1.6.2
12. jruby-1.6.2 :001 > raise ArgumentError.new ArgumentError: ArgumentError from (irb):1:in `evaluate' from org/jruby/RubyKernel.java:1088:in `e from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:158:in `eval_input' from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:271:in `signal_status' from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:155:in `eval_input' from org/jruby/RubyKernel.java:1419:in `l from org/jruby/RubyKernel.java:1191:in `c from /Users/david/.rvm/rubies/jruby-1.6.2 irb.rb:154:in `eval_input' from /Users/david/.rvm/rubies/jruby-1.6.2
13. your ruby code is our test case
14. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
15. Rspec describe "glob file path" do it "lists contents of a file" do dir = Dir.new(@local_file_path) dir.entries.should include("junit.jar") end end
16. follow the specification
17. RubySpec describe "Dir.entries" do ... it "returns an Array of filenames in an existing directory including dotfiles" do ...
18. RubySpec describe "Dir.entries" do ... ruby_version_is "1.9" do it "calls #to_path on ..." do ...
19. RubySpec $ bin/jruby -S mspec \ spec/ruby/core/dir/entries_spec.rb $ bin/jruby --1.9 -S mspec \ spec/ruby/core/dir/entries_spec.rb
20. go to the source
21. ruby code static VALUE dir_entries(int argc, VALUE *argv, VALUE io) { VALUE dir; dir = dir_open_dir(argc, argv); return rb_ensure(rb_Array, dir, dir_close, dir); }
22. taming the beast
23. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
24. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
25. Ruby class $ vi src/org/jruby/RubyDir.java @JRubyClass(name = "Dir", include = "Enumerable") public class RubyDir extends RubyObject {
26. Ruby class $ vi src/org/jruby/RubyDir.java @JRubyClass(name = "Dir", include = "Enumerable") public class RubyDir extends RubyObject {
27. Ruby class $ vi src/org/jruby/RubyDir.java @JRubyClass(name = "Dir", include = "Enumerable") public class RubyDir extends RubyObject {
28. Ruby class $ vi src/org/jruby/RubyDir.java @JRubyClass(name = "Dir", include = "Enumerable") public class RubyDir extends RubyObject {
29. Ruby class $ vi src/org/jruby/RubyDir.java @JRubyClass(name = "Dir", include = "Enumerable") public class RubyDir extends RubyObject {
30. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
31. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
32. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
33. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
34. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
35. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
36. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
37. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
38. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
39. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
40. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
41. Ruby method @JRubyMethod(name = "mkdir", required = 1, optional = 1, meta = true, compat = RUBY1_8) public static IRubyObject mkdir(IRubyObject recv, IRubyObject[] args) {
42. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
43. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
44. initialize @JRubyMethod(compat = RUBY1_8) public IRubyObject initialize(IRubyObject arg) private static final ObjectAllocator DIR_ALLOCATOR = new ObjectAllocator()
45. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
46. Test::Unit def test_dir_enumerable Dir.mkdir("./testDir_1") d = Dir.new("./testDir_1") assert(d.kind_of?(Enumerable)) end
47. Ruby module $ vi src/org/jruby/RubyKernel.java @JRubyModule(name="Kernel") public class RubyKernel {
48. Ruby module @JRubyModule(name="Kernel") public class RubyKernel { $ vi src/org/jruby/RubyKernel.java
49. Ruby module $ vi src/org/jruby/RubyObject.java @JRubyClass(name="Object", include="Kernel") public class RubyObject extends ... {
50. Ruby module @JRubyMethod(name = {"kind_of?", "is_a?"}, required = 1) public static RubyBoolean kind_of_p (ThreadContext context, IRubyObject recv, IRubyObject type) {
51. Ruby module @JRubyMethod(name = {"kind_of?", "is_a?"}, required = 1) public static RubyBoolean kind_of_p (ThreadContext context, IRubyObject recv, IRubyObject type) {
52. Ruby module @JRubyMethod(name = {"kind_of?", "is_a?"}, required = 1) public static RubyBoolean kind_of_p (ThreadContext context, IRubyObject recv, IRubyObject type) {
53. learn more
54. by Hiroshi Nakamura http://tinyurl.com/ jruby-hacking-guide
55. by R.J. Lorimer http://tinyurl.com/ distilling-jruby
56. http://jruby.org
57. thank you!
58. Credits Charles Nutter’s Photo Booth http://www.flickr.com/photos/zpeckler/2648345658/ http://www.flickr.com/photos/dcmetroblogger/3298543398/ http://www.flickr.com/photos/jenny-pics/4520503357/