Fibers

Transcript

1. Fibers DENIS DEFREYNE / RUG::B / MARCH 2ND, 2017
2. Basics 2
3. 3 f = lambda do puts "hi" end f.call
4. 3 f = lambda do puts "hi" end f.call hi
5. 4 f = Fiber.new do puts "hi" end f.resume
6. 4 f = Fiber.new do puts "hi" end f.resume hi
7. 5 f = lambda do puts "hi" end f.call hi
8. 6 f = lambda do puts "hi" return puts "bye" end f.call
9. 6 f = lambda do puts "hi" return puts "bye" end f.call hi
10. 7 f = Fiber.new do puts "hi" return puts "bye" end f.resume
11. 7 f = Fiber.new do puts "hi" return puts "bye" end f.resume hi
12. 7 f = Fiber.new do puts "hi" return puts "bye" end f.resume hi sample.rb:3:
 in`block in <main>':
 unexpected return
 (LocalJumpError)
13. 8 f = Fiber.new do puts "hi" Fiber.yield puts "bye" end f.resume
14. 8 f = Fiber.new do puts "hi" Fiber.yield puts "bye" end f.resume hi
15. 9 f = lambda do puts "hi" end f.call
 hi
16. 10 f = lambda do puts "hi" end f.call f.call
17. 10 f = lambda do puts "hi" end f.call f.call hi hi
18. 11 f = Fiber.new do puts "hi" end f.resume f.resume
19. 11 f = Fiber.new do puts "hi" end f.resume f.resume hi
20. 11 f = Fiber.new do puts "hi" end f.resume f.resume hi a.rb:6:
 in `resume':
 dead fiber called
 (FiberError)
21. 12 f = lambda do puts "hi" return puts "bye" end f.call
 hi

22. 13 f = lambda do puts "hi" return puts "bye" end f.call f.call
23. 13 f = lambda do puts "hi" return puts "bye" end f.call f.call hi hi
24. 14 f = Fiber.new do puts "hi" Fiber.yield puts "bye" end f.resume f.resume
25. 14 f = Fiber.new do puts "hi" Fiber.yield puts "bye" end f.resume f.resume hi bye
26. 15 Create a fiber Fiber.new { … } Start running a fiber f.resume Resume an running fiber f.resume Return from a fiber Fiber.yield
27. 16 f = Fiber.new do puts 'hi' end f.resume hi
28. 17 f = Fiber.new do |a| puts a end f.resume('hi')
29. 17 f = Fiber.new do |a| puts a end f.resume('hi') hi
30. 18 f = Fiber.new do |a| puts a
 
 end f.resume('hi')
 hi
31. 19 f = Fiber.new do |a| puts a Fiber.yield puts 'bye' end f.resume('hi') f.resume hi
 bye
32. 20 f = Fiber.new do |a| puts a b = Fiber.yield puts b end f.resume('hi') f.resume('bye')
33. 20 f = Fiber.new do |a| puts a b = Fiber.yield puts b end f.resume('hi') f.resume('bye') hi bye
34. 21 f = Fiber.new do puts 'hi' end f.resume hi
35. 22 f = Fiber.new do 'hi' end puts f.resume
36. 22 f = Fiber.new do 'hi' end puts f.resume hi
37. 23 f = Fiber.new do puts 'hi' end f.resume hi

38. 24 f = Fiber.new do puts 'hi' Fiber.yield 'bye' end f.resume puts f.resume hi
 bye
39. 25 f = Fiber.new do
 Fiber.yield('hi')
 'bye' end puts f.resume puts f.resume
40. 25 f = Fiber.new do
 Fiber.yield('hi')
 'bye' end puts f.resume puts f.resume hi bye
41. 26 Create a fiber Fiber.new { … } Start running a fiber f.resume(…) Resume an running fiber f.resume(…) Return from a fiber Fiber.yield(…)
42. Five (Practical) Applications 27
43. 0. Async, non-blocking IO
 and maybe reactive things 28
44. (Use your imagination here) 29
45. 1. Infinite lists 30
46. 31 
 f = Fiber.new do Fiber.yield(0) Fiber.yield(1) Fiber.yield(2) … end puts f.resume puts f.resume puts f.resume 0 1 2
47. 32 f = Fiber.new do v = 0 loop do Fiber.yield(v) v += 1 end end puts f.resume puts f.resume puts f.resume 0 1 2
48. 33 class Ints def initialize @f = Fiber.new { … } end def each loop do yield(@f.resume) end end end
49. 34 Ints.new.each do |i| puts i end
50. 34 Ints.new.each do |i| puts i end 0 1 2 3 4 5 6 7 8 9 10 11 12 13
51. 35 Ints = Enumerator.new do |y| v = 0 loop do y << v v += 1 end end
52. (You don’t need fibers for this.) 36
53. 2. Wizards 37
54. 38 What is your first name? > Denis Hi, Denis. What is your last name? > Defreyne Got it — Defreyne! Thanks for your help, Denis Defreyne! Bye-bye for now!
55. 39 first_name = ask "What is your first name?" say "Hi, #{first_name}." last_name = ask "What is your last name?" say "Got it -- #{last_name}!" say "Thanks for your help, #{first_name}!" say "Bye-bye for now!" stop
56. 40 def ask(s) puts s print '> ' gets.chomp end def say(s) puts s end def stop end
57. 41 first_name = ask "What is your first name?" say "Hi, #{first_name}." last_name = ask "What is your last name?" say "Got it -- #{last_name}!" say "Thanks for your help, #{first_name}!" say "Bye-bye for now!" stop
58. 42 wizard = Fiber.new do first_name = ask "What is your first name?" say "Hi, #{first_name}." last_name = ask "What is your last name?" say "Got it -- #{last_name}!" say "Thanks for your help, #{first_name}!" say "Bye-bye for now!" stop end
59. 43 def ask(s) Fiber.yield(Question.new(s)) end def say(s) Fiber.yield(Statement.new(s)) end def stop Fiber.yield(Stop.new) end
60. 44 answer = nil loop do instruction = wizard.resume(answer) case instruction when Question when Statement when Stop end end
61. 45 answer = nil loop do instruction = wizard.resume(answer) case instruction when Question puts instruction.text print '> ' answer = gets.chomp when Statement when Stop end end
62. 46 answer = nil loop do instruction = wizard.resume(answer) case instruction when Question puts instruction.text print '> ' answer = gets.chomp when Statement puts instruction.text when Stop end end
63. 47 answer = nil loop do instruction = wizard.resume(answer) case instruction when Question puts instruction.text print '> ' answer = gets.chomp when Statement puts instruction.text when Stop break end end
64. We’ve separated what to do (wizard) from how to do it (CLI, GUI, …) 48
65. 49 pieces = [] answer = nil loop do instruction = wizard.resume(answer) case instruction when Question when Statement when Stop end end
66. 50 when Question pieces << instruction.text pieces << '<form method="post" action="/">' pieces << '<input type="text" name="answer">' pieces << '<input type="submit">' pieces << '</form>' return pieces.join(' ')
67. 51 when Statement pieces << instruction.text
68. 52 when Stop return pieces.join(' ')
69. 3. Resumable exceptions 53
70. 54 handle_exception do puts 'before' puts Boom.new.throw puts 'after' end.…
71. 55 handle_exception do puts 'before' puts Boom.new.throw puts 'after' end.on(Boom) do |e| e.resume('exceptional') end.…
72. 56 handle_exception do puts 'before' puts Boom.new.throw puts 'after' end.on(Boom) do |e| e.resume('exceptional') end.run
73. 57 handle_exception do puts 'before' puts Boom.new.throw puts 'after' end.on(Boom) do |e| e.resume('exceptional') end.run before exceptional after
74. 58 handle_exception do puts 'before' puts Boom.new.throw puts 'after' end.run before sample.rb:31:
 in `block in run': ohnoes kaboom
 (Boom)
75. 4. Run-time dependencies 59
76. 60 http://nanoc.ws Nanoc
77. 61 page 1 page 2 page 3
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90. 63 Create a fiber Fiber.new { … } Start running a fiber f.resume(…) Resume an running fiber f.resume(…) Return from a fiber Fiber.yield(…)
91. 64 Q&A Find me at @ddfreyne on Twitter, or denis@stoneship.org.