Fuzion • Idioms • Idiom # 33: Atomically read and update variable

Idiom # 33: Atomically read and update variable

Code

x := concur.atomic 0

for y := x.read, x.read
while !x.compare_and_set y (f y)

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x := concur.atomic 0
for y := x.read, x.read
while !x.compare_and_set y (f y)
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

Running Example

ex33 =>

  # Note that this code does not solve the ABA problem: https://en.wikipedia.org/wiki/ABA_problem

  f(i) => i+1

  x := concur.atomic 0

  _ := for y := x.read, x.read
       while !x.compare_and_set y (f y)

  say x.read

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ex33 =>
  # Note that this code does not solve the ABA problem: https://en.wikipedia.org/wiki/ABA_problem
  f(i) => i+1
  x := concur.atomic 0
  _ := for y := x.read, x.read
       while !x.compare_and_set y (f y)
  say x.read
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
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What are effects?

last changed: 2025-05-13

next: Idiom # 34: Create a Set of objects