An introduction to fibers

Transcript

1. Fibers
   

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2. An

   introduction

   to
   Denis Defreyne

   Ruby Wine

   April 13th, 2019
   Fibers
   

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3. 3
   1.
   

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4. 3
   1. 2.
   

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5. Basics
   4
   

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6. 5
   f = lambda do
   puts "giraffe"
   end
   f.call
   

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7. 5
   f = lambda do
   puts "giraffe"
   end
   f.call
   giraffe
   

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8. 6
   f = Fiber.new do
   puts "giraffe"
   end
   f.resume
   

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9. 6
   f = Fiber.new do
   puts "giraffe"
   end
   f.resume
   giraffe
   

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10. Photo by Harshil Gudka on Unsplash
    

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11. 8
    f = lambda do
    puts "zebra"
    end
    f.call
    zebra
    

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12. 9
    f = lambda do
    puts "zebra"
    return
    puts "invisible zebra"
    end
    f.call
    

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13. 9
    f = lambda do
    puts "zebra"
    return
    puts "invisible zebra"
    end
    f.call
    zebra
    

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14. 10
    f = Fiber.new do
    puts "zebra"
    return
    puts "invisible zebra"
    end
    f.resume
    

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15. 10
    f = Fiber.new do
    puts "zebra"
    return
    puts "invisible zebra"
    end
    f.resume
    zebra
    

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16. 10
    f = Fiber.new do
    puts "zebra"
    return
    puts "invisible zebra"
    end
    f.resume
    zebra
    sample.rb:3:

    in `block in ':

    unexpected return

    (LocalJumpError)
    

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17. 11
    f = Fiber.new do
    puts "zebra"
    Fiber.yield
    puts "invisible zebra"
    end
    f.resume
    

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18. 11
    f = Fiber.new do
    puts "zebra"
    Fiber.yield
    puts "invisible zebra"
    end
    f.resume
    zebra
    

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19. Photo by Arleen wiese on Unsplash
    

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20. 13
    f = lambda do
    puts "donkey"
    end
    f.call

    donkey
    

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21. 14
    f = lambda do
    puts "donkey"
    end
    f.call
    f.call
    

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22. 14
    f = lambda do
    puts "donkey"
    end
    f.call
    f.call
    donkey
    donkey
    

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23. 15
    f = Fiber.new do
    puts "donkey"
    end
    f.resume
    f.resume
    

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24. 15
    f = Fiber.new do
    puts "donkey"
    end
    f.resume
    f.resume
    donkey
    

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25. 15
    f = Fiber.new do
    puts "donkey"
    end
    f.resume
    f.resume
    donkey
    a.rb:6:

    in `resume':

    dead fiber called

    (FiberError)
    

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26. Photo by Spencer Watson on Unsplash
    

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27. 17
    f = lambda do
    puts "kangaroo"
    return
    puts "wallaby"
    end
    f.call

    kangaroo

    

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28. 18
    f = lambda do
    puts "kangaroo"
    return
    puts "wallaby"
    end
    f.call
    f.call
    

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29. 18
    f = lambda do
    puts "kangaroo"
    return
    puts "wallaby"
    end
    f.call
    f.call
    kangaroo
    kangaroo
    

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30. 19
    f = Fiber.new do
    puts "kangaroo"
    Fiber.yield
    puts "wallaby"
    end
    f.resume
    f.resume
    

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31. 19
    f = Fiber.new do
    puts "kangaroo"
    Fiber.yield
    puts "wallaby"
    end
    f.resume
    f.resume
    kangaroo
    wallaby
    

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32. Photo by Austin Elder on Unsplash
    

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33. Image by sandid from Pixabay
    

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34. 22
    f = Fiber.new { … }
    Create a fiber
    

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35. 22
    f = Fiber.new { … }
    Create a fiber
    f.resume
    Start or resume a fiber
    

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36. 22
    f = Fiber.new { … }
    Create a fiber
    f.resume
    Start or resume a fiber
    Fiber.yield
    Return from a fiber
    

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37. 23
    f = Fiber.new do
    puts 'quokka'
    end
    f.resume
    quokka
    

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38. 24
    f = Fiber.new do |a|
    puts a
    end
    f.resume('quokka')
    

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39. 24
    f = Fiber.new do |a|
    puts a
    end
    f.resume('quokka')
    quokka
    

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40. Image by Tracey Wong from Pixabay
    

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41. 26
    f = Fiber.new do |a|
    puts a

    

    end
    f.resume('samoyed')

    samoyed
    

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42. 27
    f = Fiber.new do |a|
    puts a
    Fiber.yield
    puts 'arctic fox'
    end
    f.resume('samoyed')
    f.resume
    samoyed

    arctic fox
    

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43. 28
    f = Fiber.new do |a|
    puts a
    b = Fiber.yield
    puts b
    end
    f.resume('samoyed')
    f.resume('arctic fox')
    

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44. 28
    f = Fiber.new do |a|
    puts a
    b = Fiber.yield
    puts b
    end
    f.resume('samoyed')
    f.resume('arctic fox')
    samoyed
    arctic fox
    

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45. Image by coolcoolleah from Pixabay
    

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46. Photo by Jonatan Pie on Unsplash
    

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47. 31
    f = Fiber.new do
    puts 'red panda'
    end
    f.resume
    red panda
    

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48. 32
    f = Fiber.new do
    'red panda'
    end
    puts f.resume
    

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49. 32
    f = Fiber.new do
    'red panda'
    end
    puts f.resume
    red panda
    

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50. Photo by Michael Payne on Unsplash
    

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51. 34
    f = Fiber.new do
    puts 'maine coon'
    end
    f.resume
    maine coon

    

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52. 35
    f = Fiber.new do
    puts 'maine coon'
    Fiber.yield
    'raccoon'
    end
    f.resume
    puts f.resume
    maine coon

    raccoon
    

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53. 36
    f = Fiber.new do

    Fiber.yield('maine coon')

    'raccoon'
    end
    puts f.resume
    puts f.resume
    

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54. 36
    f = Fiber.new do

    Fiber.yield('maine coon')

    'raccoon'
    end
    puts f.resume
    puts f.resume
    maine coon
    raccoon
    

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55. Photo by Bee Felten-Leidel on Unsplash
    

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56. Photo by Gary Bendig on Unsplash
    

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57. 39
    f = Fiber.new { |…| … }
    Create a fiber
    

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58. 39
    f = Fiber.new { |…| … }
    Create a fiber
    r = f.resume(…)
    Start or resume a fiber
    

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59. 39
    f = Fiber.new { |…| … }
    Create a fiber
    r = f.resume(…)
    Start or resume a fiber
    a = Fiber.yield(…)
    Return from a fiber
    

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60. Three
    Practical
    Applications
    40
    

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61. 1.
    Generators
    41
    

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62. 42
    [7, 2, 4].each do |num|
    puts num
    end
    7
    2
    4
    

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63. 43
    class PeopleDirectory
    end
    

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64. 44
    class PeopleDirectory
    RADIA = 'Dr. Radia Perlman'
    KATIE = 'Dr. Katie Bouman'
    ANITA = 'Dr. Anita Borg'
    end
    

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65. 45
    class PeopleDirectory
    RADIA = 'Dr. Radia Perlman'
    KATIE = 'Dr. Katie Bouman'
    ANITA = 'Dr. Anita Borg'
    def each
    end
    end
    

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66. 46
    class PeopleDirectory
    RADIA = 'Dr. Radia Perlman'
    KATIE = 'Dr. Katie Bouman'
    ANITA = 'Dr. Anita Borg'
    def each
    yield RADIA
    yield KATIE
    yield ANITA
    end
    end
    

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67. 47
    class PeopleDirectory
    RADIA = 'Dr. Radia Perlman'
    KATIE = 'Dr. Katie Bouman'
    ANITA = 'Dr. Anita Borg'
    def each
    yield RADIA
    yield KATIE
    yield ANITA
    end
    end
    PeopleDirectory.new
    

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68. 48
    class PeopleDirectory
    RADIA = 'Dr. Radia Perlman'
    KATIE = 'Dr. Katie Bouman'
    ANITA = 'Dr. Anita Borg'
    def each
    yield RADIA
    yield KATIE
    yield ANITA
    end
    end
    PeopleDirectory.new.each do |name|
    puts name
    end
    

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69. 49
    class PeopleDirectory
    RADIA = 'Dr. Radia Perlman'
    KATIE = 'Dr. Katie Bouman'
    ANITA = 'Dr. Anita Borg'
    def each
    yield RADIA
    yield KATIE
    yield ANITA
    end
    end
    PeopleDirectory.new.each do |name|
    puts name
    end
    Dr. Radia Perlman
    Dr. Katie Bouman
    Dr. Anita Borg
    

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70. 50
    class LinearCongruentialGenerator
    

    

    

    

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71. 51
    class LinearCongruentialGenerator
    M = 0x7FFFFFF
    A = 1103515245
    C = 12345
    

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72. 52
    class LinearCongruentialGenerator
    M = 0x7FFFFFF
    A = 1103515245
    C = 12345
    def initialize(seed)
    @value = seed
    end
    

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73. 53
    class LinearCongruentialGenerator
    M = 0x7FFFFFF
    A = 1103515245
    C = 12345
    def initialize(seed)
    @value = seed
    end
    def next
    @value = (A * @value + C) % M
    end
    end
    

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74. 54
    class LinearCongruentialGenerator
    M = 0x7FFFFFF
    A = 1103515245
    C = 12345
    def initialize(seed)
    @value = seed
    end
    def next
    @value = (A * @value + C) % M
    end
    end
    rng =
    LinearCongruentialGenerator.new(123)
    

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75. 55
    class LinearCongruentialGenerator
    M = 0x7FFFFFF
    A = 1103515245
    C = 12345
    def initialize(seed)
    @value = seed
    end
    def next
    @value = (A * @value + C) % M
    end
    end
    rng =
    LinearCongruentialGenerator.new(123)
    p rng.next
    p rng.next
    p rng.next
    

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76. 56
    class LinearCongruentialGenerator
    M = 0x7FFFFFF
    A = 1103515245
    C = 12345
    def initialize(seed)
    @value = seed
    end
    def next
    @value = (A * @value + C) % M
    end
    end
    rng =
    LinearCongruentialGenerator.new(123)
    p rng.next
    p rng.next
    p rng.next
    440917719
    357222964
    2107447239
    

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77. 57
    class LinearCongruentialGenerator
    # …
    

    

    def each
    end
    end

    

    

    

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78. 58
    class LinearCongruentialGenerator
    # …
    

    

    def each
    loop do
    end
    end
    end

    

    

    

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79. 59
    class LinearCongruentialGenerator
    # …
    

    

    def each
    loop do
    self.next
    end
    end
    end

    

    

    

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80. 60
    class LinearCongruentialGenerator
    # …
    

    

    def each
    loop do
    self.next
    yield(@value)
    end
    end
    end

    

    

    

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81. 61
    class LinearCongruentialGenerator
    # …
    include Enumerable
    def each
    loop do
    self.next
    yield(@value)
    end
    end
    end

    

    

    

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82. 62
    class LinearCongruentialGenerator
    # …
    include Enumerable
    def each
    loop do
    self.next
    yield(@value)
    end
    end
    end

    

    rng =
    LinearCongruentialGenerator.new(123)

    

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83. 63
    class LinearCongruentialGenerator
    # …
    include Enumerable
    def each
    loop do
    self.next
    yield(@value)
    end
    end
    end

    

    rng =
    LinearCongruentialGenerator.new(123)

    p rng.take(3)
    

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84. 64
    class LinearCongruentialGenerator
    # …
    include Enumerable
    def each
    loop do
    self.next
    yield(@value)
    end
    end
    end

    

    rng =
    LinearCongruentialGenerator.new(123)

    p rng.take(3)
    [440917719,
    357222964,
    2107447239]
    

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85. 65
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    

    

    

    

    

    

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86. 66
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    end

    

    

    

    

    

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87. 67
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    end
    end

    

    

    

    

    

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88. 68
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    loop do
    end
    end
    end

    

    

    

    

    

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89. 69
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    loop do
    value = (A * value + C) % M
    end
    end
    end

    

    

    

    

    

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90. 70
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    loop do
    value = (A * value + C) % M
    Fiber.yield(value)
    end
    end
    end

    

    

    

    

    

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91. 71
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    loop do
    value = (A * value + C) % M
    Fiber.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    

    

    

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92. 72
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    loop do
    value = (A * value + C) % M
    Fiber.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    p rng.resume

    p rng.resume

    p rng.resume
    

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93. 73
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Fiber.new do
    loop do
    value = (A * value + C) % M
    Fiber.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    p rng.resume

    p rng.resume

    p rng.resume
    440917719
    357222964
    2107447239
    

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94. 74
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Enumerator.new do |enum|
    loop do
    value = (A * value + C) % M
    enum.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    p rng.next

    p rng.next

    p rng.next
    440917719
    357222964
    2107447239
    

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95. 75
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Enumerator.new do |enum|
    loop do
    value = (A * value + C) % M
    enum.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    p rng.next

    p rng.next

    p rng.next
    440917719
    357222964
    2107447239
    

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96. 76
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Enumerator.new do |enum|
    loop do
    value = (A * value + C) % M
    enum.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    p rng.take(2)

    

    

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97. 77
    M = 0x7FFFFFFF
    A = 1103515245
    C = 12345
    def make_rng(value)
    Enumerator.new do |enum|
    loop do
    value = (A * value + C) % M
    enum.yield(value)
    end
    end
    end

    

    rng = make_rng(123)
    p rng.take(2)

    

    [440917719,
    357222964]
    

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98. 1.
    Generators ✓
    78
    

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99. 2.
    Resumable computation
    79
    

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101. 81
     def compile
     end
     

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102. 82
     def compile
     queue = PriorityQueue.new(pages)
     end
     

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103. 83
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     end
     end
     

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104. 84
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     end
     end
     

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105. 85
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     compile_page(page)
     end
     end
     

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109. 87
     def compiled_content_of(page)
     @compiled_content[page]
     end

     

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110. 88
     def compiled_content_of(page)
     unless @compiled_content.key?(page)
     raise MissingDependencyError.new(page)
     end
     @compiled_content[page]
     end
     

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111. 89
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next

     

     compile_page(page)

     

     

     

     end
     end
     

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112. 90
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     begin
     compile_page(page)
     rescue MissingDependencyError => error
     end
     end
     end
     

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113. 91
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     begin
     compile_page(page)
     rescue MissingDependencyError => error
     queue.add(page)
     end
     end
     end
     

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114. 92
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     begin
     compile_page(page)
     rescue MissingDependencyError => error
     queue.add(page)
     queue.prioritize(error.missing_page)
     end
     end
     end
     

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129. 95
     def fiber_for(page)
     @fibers[page] ||=
     Fiber.new { compile_page(page) }
     end
     

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130. 96
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     fiber_for(page).resume
     end
     end
     

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131. 97
     def compiled_content_of(page)
     unless @compiled_content.key?(page)
     Fiber.yield(MissingDependency.new(page))
     end
     @compiled_content[page]
     end
     

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132. 98
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     result = fiber_for(page).resume
     end
     end
     

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133. 99
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     result = fiber_for(page).resume
     if result.is_a?(MissingDependency)
     end
     end
     end
     

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134. 100
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     result = fiber_for(page).resume
     if result.is_a?(MissingDependency)
     queue.add(page)
     end
     end
     end
     

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135. 101
     def compile
     queue = PriorityQueue.new(pages)
     until queue.empty?
     page = queue.next
     result = fiber_for(page).resume
     if result.is_a?(MissingDependency)
     queue.add(page)
     queue.prioritize(result.missing_page)
     end
     end
     end
     

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136. 102
     def compiled_content_of(page)
     unless @compiled_content.key?(page)
     Fiber.yield(MissingDependency.new(page))
     end
     @compiled_content[page]
     end
     

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137. 2.
     Resumable computation ✓
     103
     

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138. 3.
     Non-blocking I/O
     104
     

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140. 106
     urls = [
     'https://denis.ws',
     'https://denis.ws/cv',
     'https://denis.ws/software',
     'https://denis.ws/talks',
     'https://denis.ws/toolbox',
     'https://nanoc.ws',
     …
     ]
     

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141. 107
     Version 1
     (sequential)
     

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142. 108
     urls.each do |url|
     end
     

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143. 109
     urls.each do |url|
     response = Net::HTTP.get_response(URI.parse(url))
     end
     

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144. 110
     urls.each do |url|
     response = Net::HTTP.get_response(URI.parse(url))
     if response.code != "200"
     end
     end
     

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145. 111
     urls.each do |url|
     response = Net::HTTP.get_response(URI.parse(url))
     if response.code != "200"
     puts "Bad URL: #{url}"
     end
     end
     

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146. 112
     Version 2
     (threaded)
     

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147. 113
     urls.each do |url|
     response = Net::HTTP.get_response(URI.parse(url))
     if response.code != 200
     puts "Bad URL: #{url}"
     end
     end
     

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148. 114
     urls.each do |url|
     Thread.new do
     response = Net::HTTP.get_response(URI.parse(url))
     if response.code != 200
     puts "Bad URL: #{url}"
     end
     end
     end
     

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149. 115
     threads =
     urls.map do |url|
     Thread.new do
     response = Net::HTTP.get_response(URI.parse(url))
     if response.code != 200
     puts "Bad URL: #{url}"
     end
     end
     end
     

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150. 116
     threads =
     urls.map do |url|
     Thread.new do
     response = Net::HTTP.get_response(URI.parse(url))
     if response.code != 200
     puts "Bad URL: #{url}"
     end
     end
     end
     threads.each(&:join)
     

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151. 117
     Version 3
     (non-blocking IO)
     

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152. This is a low-level implementation.
     118
     CAUTION I
     

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153. Sockets must never block.
     119
     CAUTION II
     

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154. 120
     make_request_fiber('denis.ws', '/cv/').resume
     

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155. 121
     def make_request_fiber(host, path)
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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156. 122
     def make_request_fiber(host, path)
     Fiber.new do
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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157. 123
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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158. 124
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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159. 125
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     connect_ssl(socket)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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160. 126
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     connect_ssl(socket)
     write(socket, build_http_request(host, path))
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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161. 127
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     connect_ssl(socket)
     write(socket, build_http_request(host, path))
     puts read(socket, 1024)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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162. 128
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     connect_ssl(socket)
     write(socket, build_http_request(host, path))
     puts read(socket, 1024)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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163. 129
     def connect_tcp(socket)
     end
     

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164. 130
     def connect_tcp(socket)
     socket.connect_tcp
     end
     

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165. 131
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     when :wait_writable
     else
     end
     end
     

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166. 132
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     Fiber.yield
     when :wait_writable
     else
     end
     end
     

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167. 133
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     Fiber.current
     Fiber.yield
     when :wait_writable
     else
     end
     end
     

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168. 134
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     when :wait_writable
     else
     end
     end
     

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169. 135
     make_request_fiber('denis.ws', '/cv/').resume
     

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170. 136
     make_request_fiber('denis.ws', '/cv/').resume
     # … fiber got suspended; now what?
     

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171. 137
     IO.select(
     )
     

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172. 138
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     

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173. 139
     readable, writable =
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     

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174. 140
     readable, writable =
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     readable.each do |socket|
     end
     

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175. 141
     readable, writable =
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     readable.each do |socket|
     fiber = $awaiting_readable.fetch(socket)
     end
     

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176. 142
     readable, writable =
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     readable.each do |socket|
     fiber = $awaiting_readable.fetch(socket)
     fiber.resume
     end
     

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177. 143
     readable, writable =
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     readable.each do |socket|
     fiber = $awaiting_readable.fetch(socket)
     fiber.resume
     end
     writable.each do |socket|
     fiber = $awaiting_writable.fetch(socket)
     fiber.resume
     end
     

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178. 144
     loop do
     readable, writable =
     IO.select(
     $awaiting_readable.keys,
     $awaiting_writable.keys,
     )
     readable.each do |socket|
     fiber = $awaiting_readable.fetch(socket)
     fiber.resume
     end
     writable.each do |socket|
     fiber = $awaiting_writable.fetch(socket)
     fiber.resume
     end
     end
     

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179. 145
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     when :wait_writable
     else
     end
     end
     

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180. 146
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     $awaiting_readable.delete(socket)
     when :wait_writable
     else
     end
     end
     

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181. 147
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     $awaiting_readable.delete(socket)
     when :wait_writable
     Fiber.yield
     else
     end
     end
     

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182. 148
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     $awaiting_readable.delete(socket)
     when :wait_writable
     $awaiting_writable[socket] = Fiber.current
     Fiber.yield
     else
     end
     end
     

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183. 149
     def connect_tcp(socket)
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     $awaiting_readable.delete(socket)
     when :wait_writable
     $awaiting_writable[socket] = Fiber.current
     Fiber.yield
     $awaiting_writable.delete(socket)
     else
     end
     end
     

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184. 150
     def connect_tcp(socket)
     loop do
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     $awaiting_readable.delete(socket)
     when :wait_writable
     $awaiting_writable[socket] = Fiber.current
     Fiber.yield
     $awaiting_writable.delete(socket)
     else
     end
     end
     end
     

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185. 151
     def connect_tcp(socket)
     loop do
     case socket.connect_tcp
     when :wait_readable
     $awaiting_readable[socket] = Fiber.current
     Fiber.yield
     $awaiting_readable.delete(socket)
     when :wait_writable
     $awaiting_writable[socket] = Fiber.current
     Fiber.yield
     $awaiting_writable.delete(socket)
     else
     break
     end
     end
     end
     

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186. 152
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     connect_ssl(socket)
     write(socket, build_http_request(host, path))
     puts read(socket, 1024)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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187. 153
     def make_request_fiber(host, path)
     Fiber.new do
     socket = NonBlockingSSLSocket.new(host, 443)
     connect_tcp(socket)
     connect_ssl(socket)
     write(socket, build_http_request(host, path))
     puts read(socket, 1024)
     end
     end
     make_request_fiber('denis.ws', '/cv/').resume
     

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188. 154
     def connect_ssl(socket)
     end
     

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189. 155
     def connect_ssl(socket)
     socket.connect_ssl
     end
     

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190. 156
     def connect_ssl(socket)
     case socket.connect_ssl
     end
     

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191. 157
     def connect_ssl(socket)
     case socket.connect_ssl
     when :wait_readable
     when :wait_writable
     else
     end
     end
     

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192. 157
     def connect_ssl(socket)
     case socket.connect_ssl
     when :wait_readable
     when :wait_writable
     else
     end
     end
     

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193. 158
     require 'async'
     require 'async/http'
     

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194. 159
     require 'async'
     require 'async/http'
     endpoint = Async::HTTP::URLEndpoint.parse('https://denis.ws')
     

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195. 160
     require 'async'
     require 'async/http'
     endpoint = Async::HTTP::URLEndpoint.parse('https://denis.ws')
     client = Async::HTTP::Client.new(endpoint)
     

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196. 161
     require 'async'
     require 'async/http'
     endpoint = Async::HTTP::URLEndpoint.parse('https://denis.ws')
     client = Async::HTTP::Client.new(endpoint)
     Async do |task|
     end
     

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197. 162
     require 'async'
     require 'async/http'
     endpoint = Async::HTTP::URLEndpoint.parse('https://denis.ws')
     client = Async::HTTP::Client.new(endpoint)
     Async do |task|
     task.async { p client.get("/").status }
     task.async { p client.get("/cv/").status }
     task.async { p client.get("/software/").status }
     task.async { p client.get("/talks/").status }
     task.async { p client.get("/toolbox/").status }
     end
     

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198. 162
     require 'async'
     require 'async/http'
     endpoint = Async::HTTP::URLEndpoint.parse('https://denis.ws')
     client = Async::HTTP::Client.new(endpoint)
     Async do |task|
     task.async { p client.get("/").status }
     task.async { p client.get("/cv/").status }
     task.async { p client.get("/software/").status }
     task.async { p client.get("/talks/").status }
     task.async { p client.get("/toolbox/").status }
     end
     https://github.com/socketry/async
     

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199. 3.
     Non-blocking I/O ✓
     163
     

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200. 164
     1.
     

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201. 164
     1. 2.
     

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202. 164
     1. 2. 3.
     

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203. 165
     f = Fiber.new { |…| … }
     Create a fiber
     

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204. 165
     f = Fiber.new { |…| … }
     Create a fiber
     r = f.resume(…)
     Start or resume a fiber
     

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205. 165
     f = Fiber.new { |…| … }
     Create a fiber
     r = f.resume(…)
     Start or resume a fiber
     a = Fiber.yield(…)
     Return from a fiber
     

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206. Now you know
     everything
     about Fibers.
     

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207. Q&A
     Find me at @ddfreyne on Twitter, or at denis.ws!
     

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