slides for RubyConf Taiwan 2014

1. How to debug mrubyHow to debug mruby
RubyConf.tw 2014RubyConf.tw 2014
Team YamanekkoTeam Yamanekko
Yurie Yamane / Masayoshi TakahashiYurie Yamane / Masayoshi Takahashi

2. 自我介紹
Who are we?

3. Who are we
●
やまね ゆりえ (Yurie Yamane)
●
高橋征義 (Masayoshi Takahashi)
●
ちー (Chie)

4. Team Yamanekko
Who are we

5. http://mrb.h2so5.net/

6. 電子書出版社
http://tatsu-zine.com/
Tatsu-zine Publishing Inc.

9. http://ruby-no-kai.org/

10. http://rubykaigi.org/2014

11. http://rubykaigi.org/2015

12. CFP will be opened soon
公開徵求講者

13. our talks
到現在的經歷

14. Our talks
RubyConf.tw 2012

15. Our talks
OSDC.tw 2013

16. RubyConf 2013
https://www.flickr.com/photos/igaiga/10836637785/

17. Demo
演示

18. STM32F4的演示
Push Button
Push Button
Power ON
blinking
mode
tilt sensor
mode

19. Our problem
我們的問題

20. mruby core
*.rb (stdlib)
*.rb (your code)
C/C++
libmruby.a
Bytecode
(C String)
mrbgems
Bytecode
(C String)

21. mruby core
*.rb (stdlib)
*.rb (your code)
C/C++
mrbgems
Ruby
C

22. mrb_led_toggle

23. debugging in C → Eclipse+CDT

24. debugging in Ruby → ???

25. add breakpoint in C
●
aaa
●
Bbb
●
mrbc
breakpoint
mrbgems
C part in
Application

26. add breakpoint in Ruby
●
aaa
●
Bbb
●
mrbc
breakpoint

27. Today's Topic
今天的主題

28. Debug
除錯

29. https://www.flickr.com/photos/monkeymashbutton/7618269720/https://www.flickr.com/photos/monkeymashbutton/7618269720/

30. CRuby的除錯
Debugging in CRuby

31. Debugging in CRuby
●
p || printf
●
irb
●
ruby-debug || bybug

32. Debugging in CRuby
●
p || printf
●
irb
●
ruby-debug || bybug

33. mruby/src/vm.c

34. STDIO is an option in mruby

35. Debugging in CRuby
●
p || printf
●
irb
●
ruby-debug || bybug

38. Debugging in CRuby
●
p || printf
●
irb
●
ruby-debug || bybug

39. Debugging in CRuby
●
p || printf
●
irb
●
ruby-debug || bybug
mruby has no debugger (yet)
–
田中先生 will develop mruby debugger (in
this year?)

40. Issues in mruby
●
embedding into C/C++ apps
–
mruby's code is just a part of application
–
We need to debug C/C++ code AND ruby code
●
ruby-debug is only Ruby-level debugger
–
GDB && ruby-debug ??

41. What we want to do
●
adding breakpoint in Ruby AND C
●
step over/into/return in Ruby AND C
●
show stacktrace in Ruby AND C
●
show variable in Ruby AND C
–
it's different from ruby-debug

42. We can do them in C level
https://www.sourceware.org/gdb/

43. our solution
●
“hybrid debugger”
–
C-level debugger + Ruby-level extension
–
Ruby debugger on GDB

44. How to debug mrubyHow to debug mruby
RubyConf.tw 2014RubyConf.tw 2014
Team YamanekkoTeam Yamanekko
Yurie Yamane / Masayoshi TakahashiYurie Yamane / Masayoshi Takahashi
make a debugger tomake a debugger to

45. Our debugger status
●
just started (not finished yet Orz)
●
We talk how it works, showing
simple demo with gdb and Eclipse
plugin

46. m
http://ruby-hacking-guide.github.io/

47. mrbc and mrubyVM
*.rb *.mrb mrubyVMmrbc
Compile
Ruby Bytecode
Execute

48. mrbc and mrubyVM
*.rb *.mrb mrubyVMmrbc
Compile
Ruby Bytecode
Execute
mruby VM don't see
original code in Ruby

49. bytecode structure
●
We made mruby bytecode parser
–
mrb_parser (v0.0.1)
–
http://rubygems.org/gems/mrb_parser
–
https://github.com/yamanekko/mrb_parser

51. bytecode structure
RITE Section (Header)
IREP Section
END Section
IREP
Record
*.mrb

52. http://commons.wikimedia.org/wiki/File:Dialog-warning-orange.svg
without -g option,
mrbc doesn't generate
mappings between line
numbers of ruby souce code
and bytecodes.

53. mrbc and mrubyVM
*.rb *.mrb
Compile
Ruby
Bytecode with
debug section
Execute
mrbc -g
mrbc mrubyVM

54. bytecode structure
RITE Section(Header)
IREP Section
END Section
IREP Record
DEBUG Section
DEBUG Info
*.mrb
corresponding

56. bytecode structure
RITE Section
IREP Section
END Section
IREP Record
DEBUG Section
DEBUG Info
*.mrb
corresponding

59. i=1+2
p i

60. http://commons.wikimedia.org/wiki/File:Dialog-warning-orange.svg
number of byte code
≠
line number of Ruby code
not 1 to 1 mapping

61. mruby VM

62. mruby VM
●
src/vm.c
●
mrb_context_run()
●
≒ case statements within loops

63. mrb_context_run()

67. http://commons.wikimedia.org/wiki/File:Dialog-warning-orange.svg
You should define
ENABLE_DEBUG
in mrbconf.h

68. ENABLE_DEBUG in mrbconf.h

69. mrb_state has code_fetch_hook

70. setting code_fetch_hook function

72. GDB demo

73. Eclipse

74. Eclipse + CDT
●
CDT = C/C++ Development Tooling
–
support various toolchains
–
standard make build
–
source navigation
–
various source knowledge tools

75. Eclipse + CDT meets mruby
Eclipse Platform
DSF-GDB
target application
(+mruby)
GDB/MI
DSF
CDT
mrubydebugger

76. Demo
演示

77. Conclusion
結語

78. Conclusion
●
programming in mruby is fun
●
debugging in mruby is hard
●
making debugger is harder than
that
●
Cool tool helps you and makes less
hard

79. TODO
●
step into/step over
●
show backtrace
●
show variables

80. Kernel#local_variables

82. TODO
●
extending *.mrb
●
adding LVAR section???

83. Thanks!
Happy mruby Hacking!
special thanks to: